tag:blogger.com,1999:blog-49186152116058527202024-03-13T21:30:53.592+05:30About InstrumentationA Blog For Instrumentation Engineering StudentsSijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.comBlogger114125tag:blogger.com,1999:blog-4918615211605852720.post-3635154472597577972023-01-10T17:43:00.001+05:302023-01-10T17:43:07.133+05:30<p> </p><h2><a href="http://aboutinstrumentation.blogspot.com/p/all-posts-list.html" target="_blank">CLICK HERE TO VIEW ALL POSTS</a></h2>Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-886640210824194832023-01-10T17:35:00.002+05:302023-01-10T17:35:52.373+05:30Instrumentation Engineer: Next steps for Professional Development<p>There are a variety of certification courses that an instrumentation engineer can take to improve their career. Here are a few options:</p><p></p><ul style="text-align: left;"><li><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6QbvjS7jPQnlipwf2CqaxKHvIBGv3hXUR9BaPBYlQeft0Oy041B43r3a8h0JMQLXoqFKtNQNbuyuHu920ee3QwDlCPYZLLLPktshw9w3U-HIr6x2KMIenD2qPh28jO8GZL8-inDuBSU2E_j3efB13vaNPw9XahXe68q_LlJVtM24Vbmt0sQxTNvFd0Q/s1024/DALL%C2%B7E%202023-01-10%2015.02.57%20-%20Professional%20Engineer%20(PE)%20%20,%20digital%20image.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1024" data-original-width="1024" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6QbvjS7jPQnlipwf2CqaxKHvIBGv3hXUR9BaPBYlQeft0Oy041B43r3a8h0JMQLXoqFKtNQNbuyuHu920ee3QwDlCPYZLLLPktshw9w3U-HIr6x2KMIenD2qPh28jO8GZL8-inDuBSU2E_j3efB13vaNPw9XahXe68q_LlJVtM24Vbmt0sQxTNvFd0Q/w200-h200/DALL%C2%B7E%202023-01-10%2015.02.57%20-%20Professional%20Engineer%20(PE)%20%20,%20digital%20image.png" width="200" /></a></div>Certified Control Systems Technician (CCST) - offered by the ISA (International Society of Automation) - This certification demonstrates an individual's knowledge and understanding of the principles of control systems and the ability to apply that knowledge in the workplace.<br /></li><li>Professional Engineer (PE) - offered by the National Council of Examiners for Engineering and Surveying (NCEES) - This certification demonstrates an individual's knowledge and understanding of the principles of engineering, and the ability to apply that knowledge in the workplace.</li><li>Certified Measurement & Control Technician (CMCT) - offered by ISA - This certification demonstrates an individual's knowledge and understanding of measurement and control systems, as well as the ability to apply that knowledge in the workplace.</li><li>Six Sigma Green Belt or Black Belt - offered by multiple organizations - Six Sigma is a data-driven approach to improving process efficiency and quality. Green Belt and Black Belt certifications demonstrate an individual's understanding of the Six Sigma methodology and the ability to apply it in the workplace.</li><li>Advanced Process Control Engineer (APC) - offered by the ISA - This certification demonstrates an individual's knowledge and understanding of advanced process control techniques, as well as the ability to apply that knowledge in the workplace.</li></ul><p></p><p><br /></p><p>It's important to note that most of this certifications require both a certain level of experience and completing a specific exam, as well as having a valid engineering degree/diploma .Additionally, you should research the certification requirements and ensure that it aligns with your career goals and the specific industry you're in or want to be in.</p>Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-91717202122612894082023-01-10T17:07:00.007+05:302023-01-10T17:19:26.101+05:30Career improvement ideas for Instrumentation Engineers working in Construction Companies<p><span style="font-family: verdana;"> Are these your questions in mind??</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"></span></p><div class="separator" style="clear: both; text-align: center;"><span style="font-family: verdana;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHqrifWXIyXTlqLW14TR6v50-_g44hIzKEVkWrbDN5ZajlYtmCfc4vfBregNIZvmBOjlYYI0fc9P31vL7KznF-HTt3Z-1Vu2iYURRbsIeb1bVPYN-o-PL8xOTaEQJRIoTCS-2f_veC2oGRnld5SGj5hohQ2QqsoBERG0957rclqTiR87Xrok33AHBMGg/s1024/DALL%C2%B7E%202023-01-10%2014.44.56%20-%20Instrumentation%20Engineer_%2010%20years%20experience,%20what's%20next_%20,%20digital%20art.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1024" data-original-width="1024" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHqrifWXIyXTlqLW14TR6v50-_g44hIzKEVkWrbDN5ZajlYtmCfc4vfBregNIZvmBOjlYYI0fc9P31vL7KznF-HTt3Z-1Vu2iYURRbsIeb1bVPYN-o-PL8xOTaEQJRIoTCS-2f_veC2oGRnld5SGj5hohQ2QqsoBERG0957rclqTiR87Xrok33AHBMGg/w200-h200/DALL%C2%B7E%202023-01-10%2014.44.56%20-%20Instrumentation%20Engineer_%2010%20years%20experience,%20what's%20next_%20,%20digital%20art.png" width="200" /></a></span></div><span style="font-family: verdana;">"Navigating Your Career as an Instrumentation Engineer: Opportunities and Strategies for Success"</span><p></p><p><br /><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">or</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">"From Construction to Control: Charting a Successful Path for Instrumentation Engineers"</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">or</span></p><p><span style="font-family: verdana;">"Career Advancement for Instrumentation Engineers: Tips, Strategies and Opportunities"</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">or</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">"Instrumentation Engineer: 10 years' experience, what's next?"</span></p><p><br /><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">Then this post is for you.</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">If you're an instrumentation engineer with 10 years of experience working in a construction company, there are a few different career paths you could consider, depending on your interests and goals. Here are a few suggestions:</span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh48KNbPtFl0rZzRrowQF9Hkm-1uxw2u5K5huWJAfiO81aJRC4dcBJVxIrHIY2jg7PbIeeg1TDDHK8z4IQHyNqPFbWssjB1CFuKqNnDZnFpzrIhSKPBw--BF3G1p1scRikxJdFZHmS-Umi1UGXJJTDhPgEqqUySnkiNfjHtL8vBWq7VIgCrjLF0J6e6ig/s1024/DALL%C2%B7E%202023-01-10%2014.42.47%20-%20From%20Construction%20to%20Control_%20Charting%20a%20Successful%20Path%20for%20Instrumentation%20Engineers%20,%20digital%20image.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1024" data-original-width="1024" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh48KNbPtFl0rZzRrowQF9Hkm-1uxw2u5K5huWJAfiO81aJRC4dcBJVxIrHIY2jg7PbIeeg1TDDHK8z4IQHyNqPFbWssjB1CFuKqNnDZnFpzrIhSKPBw--BF3G1p1scRikxJdFZHmS-Umi1UGXJJTDhPgEqqUySnkiNfjHtL8vBWq7VIgCrjLF0J6e6ig/w200-h200/DALL%C2%B7E%202023-01-10%2014.42.47%20-%20From%20Construction%20to%20Control_%20Charting%20a%20Successful%20Path%20for%20Instrumentation%20Engineers%20,%20digital%20image.png" width="200" /></a></div><p></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">Transition into a role in an engineering company: You could leverage your experience working in construction to transition into a role in an engineering company, where you would be responsible for designing and implementing instrumentation systems for process control and automation.</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">Specialize in a specific area of instrumentation: Consider focusing your efforts on mastering a particular area of instrumentation, such as process control, advanced control systems, or industrial automation. This could help you differentiate yourself in the job market and open up new opportunities.</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">Project management: With your experience, you could step into a role that manage projects that are related to your domain. As you already have the experience of working in different projects and having a understanding of the construction and production process it can help you to manage projects more efficiently.</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">Look for roles in the construction industry: While you may be interested in transitioning out of the construction industry, there may still be opportunities for you to use your skills and experience in this field. For example, you could look for roles as an instrumentation engineer or manager in a construction company or in a position that requires experience in process control and automation.</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">Training and Certification: You could also consider seeking out training and certification in areas that are in demand in your field, such as industrial automation, safety systems, and energy management. This will demonstrate your commitment to professional development and will help you to stay current with the latest trends and technologies in your field.</span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;"><br /></span></p><p><span style="font-family: verdana;">It's important to remember that every career path will have its own set of challenges and opportunities, so it's important to do your research and carefully consider which path is the best fit for you. It may also be helpful to talk to people who are currently working in the roles you're interested in to get a better understanding of what to expect.</span></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMmAWY1uSJ9P-VNVjeheBalNjMa2kcep9FLXT5WWmYKLTPpLwWwBJXAekx5KX2w9vSIcEiiUVzYSn8ObzfB1GFREb5FC1ts-HH290gDhUIe8uE2RDX3V38pvx5ZgIojd8F2UBpp-Fp2Fgyc1TUi8T8s-T9QTbjPCvn0A1-5od-zRYm7yzG0Oi8nbkIvA/s1024/DALL%C2%B7E%202023-01-10%2014.42.43%20-%20From%20Construction%20to%20Control_%20Charting%20a%20Successful%20Path%20for%20Instrumentation%20Engineers%20,%20digital%20image.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1024" data-original-width="1024" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMmAWY1uSJ9P-VNVjeheBalNjMa2kcep9FLXT5WWmYKLTPpLwWwBJXAekx5KX2w9vSIcEiiUVzYSn8ObzfB1GFREb5FC1ts-HH290gDhUIe8uE2RDX3V38pvx5ZgIojd8F2UBpp-Fp2Fgyc1TUi8T8s-T9QTbjPCvn0A1-5od-zRYm7yzG0Oi8nbkIvA/w200-h200/DALL%C2%B7E%202023-01-10%2014.42.43%20-%20From%20Construction%20to%20Control_%20Charting%20a%20Successful%20Path%20for%20Instrumentation%20Engineers%20,%20digital%20image.png" width="200" /></a></div><br /><span style="font-family: verdana;"><br /></span><p></p><p><span style="font-family: verdana;">So for Navigating Your Career as an Instrumentation Engineer: Opportunities and Strategies for Success here are the tips:</span></p><p></p><ul style="text-align: left;"><li><span style="font-family: verdana;">Understanding the different career paths available to instrumentation engineers, including roles in engineering companies, construction companies, and specialized areas such as process control and automation.</span></li><li><span style="font-family: verdana;">Tips for transitioning from a construction company to an engineering company or other specialized role in the field of instrumentation.</span></li><li><span style="font-family: verdana;">Strategies for developing specialized knowledge and skills in areas such as process control, industrial automation, and energy management to stand out in the job market.</span></li><li><span style="font-family: verdana;">The importance of continuing education and training, and suggestions for relevant certifications and training programs.</span></li><li><span style="font-family: verdana;">Case studies or profiles of successful instrumentation engineers who have navigated unique career paths in the field.</span></li><li><span style="font-family: verdana;">Sharing the challenges and opportunities of being an Instrumentation Engineer</span></li><li><span style="font-family: verdana;">The importance of networking and connecting with professionals in the field to learn about new opportunities and stay informed about industry trends.</span></li></ul><p></p>Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-14337581241743695782020-05-03T21:19:00.000+05:302020-05-03T21:19:33.630+05:30Turbidity meters<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEid3HU5MW-Zvq79ovsPYczajrlu-D7Z0L9vZFJZBOV3_7d08A0Kf9HWJYkChU5HTfNDu6tyjDlF-AnQeOvnnWl9BR_lqFajXAC4FQcXZVrD3X-Ea3IQB4MWFQSwbRPVv0mqG7U3b5DUsj_w/s1600/71vameOc8HL._SL1500_.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1416" data-original-width="1500" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEid3HU5MW-Zvq79ovsPYczajrlu-D7Z0L9vZFJZBOV3_7d08A0Kf9HWJYkChU5HTfNDu6tyjDlF-AnQeOvnnWl9BR_lqFajXAC4FQcXZVrD3X-Ea3IQB4MWFQSwbRPVv0mqG7U3b5DUsj_w/s200/71vameOc8HL._SL1500_.jpg" width="200" /></a>Very often it is necessary to measure the amount of solids suspended in fluids. In this case <b>the turbidity</b> is measured as the function of the amount of suspensions in fluids. <b>Fig. 7.10</b> schematically explains an operational principle of a transmission-type turbidity meter. A constant-candlepower lamp <b>1 </b>provides a lightbeam which passes through the lens <b>2,</b> glass windows <b>3,</b> and a sample cell <b>4</b>.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHkFmAxSLw1CJCeX5WXjJIoUetwSN1XMt8MO7vjx5tYfLuGat42yAUpUngwXPgXvXLFc6oUX9DEKeKPcbPZJny816NJkZ44pWkMKwW3_s-FZ7ALWG7s2piTX9AE5M7OpHQKsvNkQr8Vh_J/s1600/dissolved-oxygen-meter-500x500.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="336" data-original-width="499" height="134" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHkFmAxSLw1CJCeX5WXjJIoUetwSN1XMt8MO7vjx5tYfLuGat42yAUpUngwXPgXvXLFc6oUX9DEKeKPcbPZJny816NJkZ44pWkMKwW3_s-FZ7ALWG7s2piTX9AE5M7OpHQKsvNkQr8Vh_J/s200/dissolved-oxygen-meter-500x500.png" width="200" /></a>A fluid with solid suspensions to be measured flows through the sample cell. The light beam is scattered by solids in suspensions. The degree of scattering depends on the amount of solids, and hence on the turbidity of the fluid. This scattering effect is called the Tyndall effect. The light beam with reduced intensity falls on the photo cell <b>5</b> (usually photosensors), which converts the measured light intensity to an electrical signal inversely proportional to the turbidity of the fluid (or the amount of suspended solids). The scale of a device <b>6</b> for measurement of this electrical output signal is calibrated in <b>ppm</b> of solids suspended in fluid. Since the photosensor is temperature sensitive, a heater and thermostat are employed to maintain its temperature at a constant value. By matching the length of the light path to the level of turbidity, we can vary ranges of turbidity to be measured.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHqGrxQfuRT763m8QEFrl6DOhyphenhyphenACJKOl0OPYZafX3nBFVAIQX6TCSvpc-tsuMu_zwgsYcyIe8clzs2TPeVSrAJw7nx7Q5Hix0Hr1fxoDzN2NIRW3y_pdS0IhxadgueKzxdAmqYoBE_1t0i/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="268" data-original-width="598" height="284" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHqGrxQfuRT763m8QEFrl6DOhyphenhyphenACJKOl0OPYZafX3nBFVAIQX6TCSvpc-tsuMu_zwgsYcyIe8clzs2TPeVSrAJw7nx7Q5Hix0Hr1fxoDzN2NIRW3y_pdS0IhxadgueKzxdAmqYoBE_1t0i/s640/01.bmp" width="640" /></a></div>
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The formation of deposits on the windows of the sample cell reduces the accuracy of turbidity measurements, so frequent maintenance of these windows is required.<br />
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<i style="background-color: white; color: #4c4c4c; font-family: arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-48525893961321363552020-05-03T20:42:00.000+05:302020-05-03T20:46:02.068+05:30Flame ionisation detectors (analysers)<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4JrQQNJOxp3LJsHBMDSvcRAMOeUJklzaeZxs67QmxJQBGK_edZawIo_OIkxU5yhyeq9QHUfGkcE7ymHTO-sD4amuCd4CT0tWMIgK1Cn47TbsqPx9gcNG8WVdpfEHnLl7lICEe_vhvhOQn/s1600/flame-ionization-meters1413215858.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="550" data-original-width="652" height="269" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4JrQQNJOxp3LJsHBMDSvcRAMOeUJklzaeZxs67QmxJQBGK_edZawIo_OIkxU5yhyeq9QHUfGkcE7ymHTO-sD4amuCd4CT0tWMIgK1Cn47TbsqPx9gcNG8WVdpfEHnLl7lICEe_vhvhOQn/s320/flame-ionization-meters1413215858.jpg" width="320" /></a></div>
Another type of a gas detector is widely used not only in the gas chromatography, but as a separate gas analyser as well. At present it is the most sensitive gas detector used in gas chromatography. Its operational principle is based on the measurement of ion current which is developed in a flame where the ionisation of organic compounds takes place. This detector is sensitive to organic compounds, whereas it does not give response for inorganic gases.<br />
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<b>Figure 7.9</b> shows a schematic view of a flame ionisation detector. A carrier gas <b>1</b> (usually nitrogen) from the outlet of a separating column of a gas chromatograph is mixed with hydrogen <b>2</b>, and this mixture is burned in the atmosphere of air <b>3</b> in the detector jet <b>4</b>. Since even small amounts of compressor oil could effect the results of measurements, molecular sieves or a diffusion disc <b>5</b> are used to eliminate the oil from the supplied air. An ignitor coil <b>6</b> is used to ignite the nitrogen-hydrogen-air mixture leaving the jet. When this gas mixture burns very few ions are developed. A collector of ions <b>7</b> is placed above the jet close to the flame. In order to maintain ion flow from the jet to the collector the latter is kept at some positive electric potential (75-150 V) above the normally grounded jet. Thus produced the background ion current passes through the conductors via the insulated feed-through <b>8</b> to an amplifier. Then the background current is balanced (brought to zero). Now, when an organic compound leaves the separating column of the gas chromatograph, enters and burned in the jet, large amount of ions are formed in the flame. This increases the ion current (up to <span style="font-family: "times new roman" , serif; font-size: 12pt;">10</span><sup style="font-family: "Times New Roman", serif;">-12</sup> A), which is amplified in an amplifier. The compound burned in the flame. Thus we can evaluate the amount of the organic component in the analysed gas mixture.value of this current is proportional to the amount of the organic.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsLuXN8Sms0qnbTCh1NXEbqmXoyhG_vi5awGp6fIpMj7xAZvfMlyLapu_DpHT92ySxScKprlsi7B4pe2rfzC7HgGP7IBZHgUEo3Mq5ID9Rrap5-TbnuF8yo1FbJSuxN6QR0TIPC0bBQSUy/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="445" data-original-width="608" height="467" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsLuXN8Sms0qnbTCh1NXEbqmXoyhG_vi5awGp6fIpMj7xAZvfMlyLapu_DpHT92ySxScKprlsi7B4pe2rfzC7HgGP7IBZHgUEo3Mq5ID9Rrap5-TbnuF8yo1FbJSuxN6QR0TIPC0bBQSUy/s640/01.bmp" width="640" /></a></div>
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<b>Figure 7.9. </b>Schematic of a flame ionisation detector (analyser).<br />
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For simple molecules the detector response is proportional to the carbon content in the compound, whereas in the case of other compounds the response is not easy predictable. These detectors are not as temperature sensitive as thermal conductivity detectors. As we mentioned above, these detectors can be used for continuously measurements of the total hydrocarbon content in the gas mixture. In this case they are called hydrocarbon analysers.<br />
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<i style="background-color: white; color: #4c4c4c; font-family: arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-20084626751780480292020-05-03T20:03:00.000+05:302020-05-03T20:45:50.596+05:30Thermal conductivity gas analysers<div dir="ltr" style="text-align: left;" trbidi="on">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnFqJnPmlzyTKfBCJoQ0pdbBKNiRBCVl0O4t7sUa7H0n2BQgqEdSiAp1k2ZBKYIyQ1JpWuvH0KTid_k2duQ8RLBGfgfRahTtRY6zrt53Eqi7bSREiCiZcQVSGGzYFq80wL7-B6znsEG16K/s1600/alba-logo.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="264" data-original-width="379" height="138" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnFqJnPmlzyTKfBCJoQ0pdbBKNiRBCVl0O4t7sUa7H0n2BQgqEdSiAp1k2ZBKYIyQ1JpWuvH0KTid_k2duQ8RLBGfgfRahTtRY6zrt53Eqi7bSREiCiZcQVSGGzYFq80wL7-B6znsEG16K/s200/alba-logo.png" width="200" /></a>One of the simplest and earliest method for measurement of composition of binary gas mixtures is a method which uses thermal conductivity properties of gases. <b>By passing the gas to be analysed over an electrically heated filament, and thus cooling the filament to an extent that is dependent on the thermal conductivity of the gas under measurement, we can determine the gas composition.</b> The only drawback of this method is that it can be employed only to binary gas mixtures, since this analyser measures the total sample thermal conductivity, and cannot, therefore, distinguish what composition change causes the conductivity variation. However, this technique is widely used in gas chromatography for detection of the constituents of a separated gas mixture. Although they respond to most types of gas samples, thermal conductivity detectors are much less sensitive than flame-ionisation detectors.<br />
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<b>Table 7.1</b> gives values of thermal conductivities of several gases (from Huskins D.J. Quality measuring instruments in on-line process analysis, Ellis Horwood Ltd., NY, 1982, p. 199). In this table<b> k </b>is thermal conductivity of a gas.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguxUJ02U8dZuOdsuAlbTo6okplY_Ejte69uZvT9Z9d7eqlcr7IW7pPSZw7ZJO1ntzBa9yomJ-O20ex1m6gparrxIMSy6O0WRlhGAe_Q0_MYUmObWCtJDAr2C1s1-87AUr5svbciSNN-7Ef/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="594" data-original-width="1059" height="356" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguxUJ02U8dZuOdsuAlbTo6okplY_Ejte69uZvT9Z9d7eqlcr7IW7pPSZw7ZJO1ntzBa9yomJ-O20ex1m6gparrxIMSy6O0WRlhGAe_Q0_MYUmObWCtJDAr2C1s1-87AUr5svbciSNN-7Ef/s640/01.bmp" width="640" /></a></div>
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<b>Table 7.1. </b>Thermal conductivities of some gases.<br />
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A thermal conductivity gas analyser consists of three major parts, namely, measuring cell, regulated power supply and Wheatstone bridge, and a case temperature control. Fig. 7.7 shows a schematic of a four-element thermal conductivity cell. This cell presents a relatively large mass of metal (stainless steel with high thermal conductivity coefficient) to provide a stable heat sink. Flow passages and cavities are drilled in this metal for gas flow and for placement of heat-source-sensing elements, namely, hot wire filaments. These filaments may be made of platinum, platinum alloy materials, or tungsten. The filaments are used in pairs, two filaments are placed in the stream of the sample gas, and two others - in the stream of a reference gas. Increasing the number of filaments (up to eight) will increase the sensitivity of the analyser. Temperatures of these filaments are varied from 200 to 400 Deg C.<br />
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The second element of the thermal conductivity gas analyser is a regulated power supply and Wheatstone bridge (see Fig. 7.8). The Wheatstone bridge uses a high-quality regulated power supply, which delivers current between 100 and 300 mA dc. The stability of the analyser depends mostly on the accuracy of a power supply voltage regulation. Electrical terminals of filaments from thermal conductivity cell are connected to the sides of the Wheatstone bridge, filaments which are placed in the sample stream being connected to opposite sides of the bridge, the same refers to the filaments placed in the reference gas stream.<br />
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In order to increase stability of the measuring thermal conductivity cell one need to be able to maintain a constant temperature environment in it. For this purpose several types of case temperature control systems utilising on/off thermal switches are used.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCcwA5x7KTbfqOcxVn7QqCWaqMN_LYeQirAXO0bSXyAgO1hruZQSZuR4i3shDSt1E-3suETX6yjwklsY3ESPZXUb7Ys0uE3h7URNWEvFfZQpqUgMOvHWHHjig6uv3h0YpCGXZ_XYLbOYlf/s1600/02.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="523" data-original-width="581" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCcwA5x7KTbfqOcxVn7QqCWaqMN_LYeQirAXO0bSXyAgO1hruZQSZuR4i3shDSt1E-3suETX6yjwklsY3ESPZXUb7Ys0uE3h7URNWEvFfZQpqUgMOvHWHHjig6uv3h0YpCGXZ_XYLbOYlf/s400/02.bmp" width="400" /></a></div>
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<b>Figure 7.7</b>. Four-element thermal conductivity cell.<br />
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The four-element thermal conductivity cell is connected to the Wheatstone bridge (see <b>Fig. 7.8)</b>. A sample of a gas or a binary gas mixture (flow controlled from 50 to 200 cm3) to be analysed is passed through the measuring cell and across the filaments <b>1</b> and <b>2</b>, placed in the cavities of this cell. A reference gas (usually single component gas representing the major component of the gas mixture under investigation) passes across reference filaments <b>3</b> and <b>4</b>. The flow of the reference gas is controlled from 40 to 100 cm3. The reference gas is used to provide better stability due to variations of temperature and barometric pressure. A current from the regulated power supply <b>5</b> is measured by an ampermeter <b>7</b>, and this current heats the filaments. The surface temperature of filaments increases. When analysing gas passes across the filaments <b>1</b> and <b>2</b> this heat energy is conducted away from the filaments. The higher the thermal conductivity of the gas under measurement (comparing to that of the reference gas) the more heat energy is removed from the measuring filaments <b>1</b> and <b>2</b> than from the reference filaments <b>3</b> and <b>4.</b> Therefore, temperature of the measuring filaments will be lower than temperature of the reference filaments, and an electrical resistance of the measuring filaments will be lower that that of the reference ones. This will cause an unbalanced condition of the Wheatstone bridge (current flows through the ampermeter <b>6</b>), the degree of this unbalance being dependent on the composition of the gas under measurement. To bring the bridge to a new balanced condition a slide resistor <b>8</b> is used. The scale <b>9</b> of this resistor is calibrated in the units of gas composition.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK18pUTZTso7HZRy5KeGZSC2RlYLMWfr_OvUEyHnXmI09xhotu3av_POMeAUC0KdhXdb7o15KrVkeCFA6uS8z3-9NZO2cSuH4Qh6FgclKeSX0vLt4qKeYrxbrNV_dVGmk27qCLaR4vDjZw/s1600/03.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="550" data-original-width="596" height="368" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK18pUTZTso7HZRy5KeGZSC2RlYLMWfr_OvUEyHnXmI09xhotu3av_POMeAUC0KdhXdb7o15KrVkeCFA6uS8z3-9NZO2cSuH4Qh6FgclKeSX0vLt4qKeYrxbrNV_dVGmk27qCLaR4vDjZw/s400/03.bmp" width="400" /></a></div>
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<b>Figure 7.8. </b>Wheatstone bridge with a thermal conductivity cell.<br />
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<b><u>Development of an equation for output voltage of TCD: </u></b><br />
(from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 338-340):<br />
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V<span style="font-family: "times new roman" , serif; font-size: 12pt; vertical-align: sub;">ab </span>is a measure of a gas concentration. Convective heat transfer coefficient U between filament and moving gas is a function of gas thermal conductivity, k , and the average gas velocity. If gas velocity is maintained constant, then<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbcrkC9D08AtaWvHRh1iW050leIAybZT6BH5iQjRRpwoXLGRFzOPWRmse7BX0s0esENFARTHCfwi9c1h5dQ4oBdoAKVJuPuAtyPVPWb2hk8D2EnWg_KX_nuZSM7iGMp-jR24183ma3M4Mu/s1600/04.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="20" data-original-width="72" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbcrkC9D08AtaWvHRh1iW050leIAybZT6BH5iQjRRpwoXLGRFzOPWRmse7BX0s0esENFARTHCfwi9c1h5dQ4oBdoAKVJuPuAtyPVPWb2hk8D2EnWg_KX_nuZSM7iGMp-jR24183ma3M4Mu/s1600/04.bmp" /></a>.<br />
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The value of a constant self-heating current is determined as follows:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhp_TVgSAF6EusFbAuCRspoXj0Erpc7UUnqZDFCYqu-E4J7g3XqRx3KAXWllN4w4g2PNPaOXYV2l4vDquqXok4badJqOtEMnAPXp-VjSVKJPQy74mEn3Gm3bETSccXDRkV1JqzuVs_0ylx8/s1600/05.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="48" data-original-width="56" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhp_TVgSAF6EusFbAuCRspoXj0Erpc7UUnqZDFCYqu-E4J7g3XqRx3KAXWllN4w4g2PNPaOXYV2l4vDquqXok4badJqOtEMnAPXp-VjSVKJPQy74mEn3Gm3bETSccXDRkV1JqzuVs_0ylx8/s1600/05.bmp" /></a>(7.9)</div>
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where, I - total bridge current, A.<br />
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The steady-state heat balance equation:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmHQw41ARhItaMlHRsTaRxJ1dC81k2erO6VWCm-80MPBMiBfDlF3rfd_8o8u9-sS3Q9DJh-aZf25zi_wkJGsTbBEN0iXMmVPeO4MELS0nBXyAZKrXHVh2WZVS_gXQpDKYadyS6m4OabcUJ/s1600/06.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="186" data-original-width="1237" height="96" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmHQw41ARhItaMlHRsTaRxJ1dC81k2erO6VWCm-80MPBMiBfDlF3rfd_8o8u9-sS3Q9DJh-aZf25zi_wkJGsTbBEN0iXMmVPeO4MELS0nBXyAZKrXHVh2WZVS_gXQpDKYadyS6m4OabcUJ/s640/06.bmp" width="640" /></a></div>
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where<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjB-KeeVGmnAu8qhSClZSGDCuR7HNe-jtLppX8qB_YtsWlWVHgnHVcPyAXn06YYEqbc8KnbCzzZRfdzXl0oBPhOXIMO84VkuFpGB7p9eVyBNtMQ_puxmhrm2t0gh97RBWdHYuxmB3W3tf77/s1600/07.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="28" data-original-width="49" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjB-KeeVGmnAu8qhSClZSGDCuR7HNe-jtLppX8qB_YtsWlWVHgnHVcPyAXn06YYEqbc8KnbCzzZRfdzXl0oBPhOXIMO84VkuFpGB7p9eVyBNtMQ_puxmhrm2t0gh97RBWdHYuxmB3W3tf77/s1600/07.bmp" /></a></div>
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Since terms involving<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBAa-0e8T1dBu8pDU4jp6zRHyx3PRLweK_mGsl5EElmVWMvmq8SAgrztfgm_w5tkuNAgWWloYD1g5T4AAESBo10lGO3ojzBSg1l9VrOtjgEKOxn7PP7LmsACLHZ1WeX05U14Nk84mII2Yh/s1600/08.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="33" data-original-width="53" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBAa-0e8T1dBu8pDU4jp6zRHyx3PRLweK_mGsl5EElmVWMvmq8SAgrztfgm_w5tkuNAgWWloYD1g5T4AAESBo10lGO3ojzBSg1l9VrOtjgEKOxn7PP7LmsACLHZ1WeX05U14Nk84mII2Yh/s1600/08.bmp" /></a>are negligible, then<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikMCgpP3K8YxBuXZ8km-WkCRXBOUQ6GLptYhqBIAgjBApWM0l_53V6lM8crT5_Q0G3t1kyKbY774r1sKtq3etFRSpceBELkfQz54XvDVaiHtdOM6d6s0XS4ujRqw7FsfW4jSzftcvCvwDZ/s1600/09.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="165" data-original-width="1424" height="73" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikMCgpP3K8YxBuXZ8km-WkCRXBOUQ6GLptYhqBIAgjBApWM0l_53V6lM8crT5_Q0G3t1kyKbY774r1sKtq3etFRSpceBELkfQz54XvDVaiHtdOM6d6s0XS4ujRqw7FsfW4jSzftcvCvwDZ/s640/09.bmp" width="640" /></a></div>
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Substitute (7.14) into (7.10):<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiM-SH6s3OIVYGjyPdNXEGMqQrSiQ79IgJ0fEcIhulikm-7gO_Ynwyvd3xyyB7WEhyphenhyphenKk0TJcROl-p9jky0AG03qOqhvw-EuAf_q0lo3E6Uijar3_-Bv7zGKBELQ21CNRfJ0RY2IPIkSaGd/s1600/10.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="194" data-original-width="1410" height="88" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiM-SH6s3OIVYGjyPdNXEGMqQrSiQ79IgJ0fEcIhulikm-7gO_Ynwyvd3xyyB7WEhyphenhyphenKk0TJcROl-p9jky0AG03qOqhvw-EuAf_q0lo3E6Uijar3_-Bv7zGKBELQ21CNRfJ0RY2IPIkSaGd/s640/10.bmp" width="640" /></a></div>
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where,<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgzGaF0HDBwpx6uzRFaxPZziGPlctcstjNhJIUgETsgtCbWdh5Ze0UEHJeIr63p6g8XLG6qLzNda_0NFtjxBRnNoRRv1iQOIFKIUI4RU0JTNrKDc1AlsNlwHQdGU6WiotKgCR4jv38Qold/s1600/11.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="56" data-original-width="152" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgzGaF0HDBwpx6uzRFaxPZziGPlctcstjNhJIUgETsgtCbWdh5Ze0UEHJeIr63p6g8XLG6qLzNda_0NFtjxBRnNoRRv1iQOIFKIUI4RU0JTNrKDc1AlsNlwHQdGU6WiotKgCR4jv38Qold/s1600/11.bmp" /></a> (7.17)</div>
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if <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUTaaEp17PrynaNxQRLyYvWH5Gcvki3SD5CIS3UVF93nVbhy7SzCBCspycE1G2_8w0zK0cnBpgHw0XWXEclBOdIYhJZPLZUjGdWgyPbpIzJdqXqCFOKmMAeafce_ISY76RDUMs2akCz2O_/s1600/12.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="28" data-original-width="83" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUTaaEp17PrynaNxQRLyYvWH5Gcvki3SD5CIS3UVF93nVbhy7SzCBCspycE1G2_8w0zK0cnBpgHw0XWXEclBOdIYhJZPLZUjGdWgyPbpIzJdqXqCFOKmMAeafce_ISY76RDUMs2akCz2O_/s1600/12.bmp" /></a> then :<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEik1ExqC8awg6I2E9EWNHMoYBiuYiyTSI4yeVgLCYv73KALnRaijmXPilmhXYw8vcHWfV3DOo-7PSD5P9sElXCbtxM2Tk1NxCTTDw383HCvTkxBjmj1opF1nMc2ssJicRSjmRuyOqDMO7oA/s1600/13.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="76" data-original-width="90" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEik1ExqC8awg6I2E9EWNHMoYBiuYiyTSI4yeVgLCYv73KALnRaijmXPilmhXYw8vcHWfV3DOo-7PSD5P9sElXCbtxM2Tk1NxCTTDw383HCvTkxBjmj1opF1nMc2ssJicRSjmRuyOqDMO7oA/s1600/13.bmp" /></a>(7.18)</div>
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Resistances of filaments in measuring cells are equal to:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6PZpVRWMkgz9xhZMBjqH0a_PtHKjFFF6ugG37zNJvitZsd3oHQ9rSnQ1o12ozt_XFJDVNzMHWJ3TdBlBghsQa36XeeZ7NS3pwkFZ-YTbU1CSoypnZBd1s_AOgCZ0JfPU62gKw8xnSGQmV/s1600/14.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="83" data-original-width="138" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6PZpVRWMkgz9xhZMBjqH0a_PtHKjFFF6ugG37zNJvitZsd3oHQ9rSnQ1o12ozt_XFJDVNzMHWJ3TdBlBghsQa36XeeZ7NS3pwkFZ-YTbU1CSoypnZBd1s_AOgCZ0JfPU62gKw8xnSGQmV/s1600/14.bmp" /></a>(7.19)</div>
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Resistances of filaments in reference cells are equal to:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjJer15LFEcB_PJYhFHY0ohabp_19dUm8Z9R6PENTB2EExQHR5diPyq2pqQdsqe3My_eUXuav9619zrUqzYmwRlhfiZfrWfoXZEUdZlFCRamm0PfeXq2NGh1eg5tBGSyHAtAyB8pvpcCay/s1600/15.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="83" data-original-width="138" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjJer15LFEcB_PJYhFHY0ohabp_19dUm8Z9R6PENTB2EExQHR5diPyq2pqQdsqe3My_eUXuav9619zrUqzYmwRlhfiZfrWfoXZEUdZlFCRamm0PfeXq2NGh1eg5tBGSyHAtAyB8pvpcCay/s1600/15.bmp" /></a>(7.20)</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3toRhf7hvOnj8P6s5hMExyn8uqPHZnoEMWZmPnUMfhx113-Hg7mx7N8LOwsOeI1R9ILQkMG2Jk-sZP9qceIqBIT3e-Duzyv2D6IO6ETzD5spPqByWb65-OIXm41XsM0_HlqVQu1eVtgza/s1600/16.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="282" data-original-width="392" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3toRhf7hvOnj8P6s5hMExyn8uqPHZnoEMWZmPnUMfhx113-Hg7mx7N8LOwsOeI1R9ILQkMG2Jk-sZP9qceIqBIT3e-Duzyv2D6IO6ETzD5spPqByWb65-OIXm41XsM0_HlqVQu1eVtgza/s320/16.bmp" width="320" /></a>(7.21)</div>
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For a typical system:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8J1he4Mt08burOOL9saAVhJdWSn3uC7dhNzvALWSHA5_nNcCAQoor4Wvrl8Lmy9AI7fkNdkhqTBB5zRsLoOy3bvwSGUTzBOE2RBwZcaPIceXuHbMEVIOWdpnDkxAWxU8J80bbvN6KpQhW/s1600/17.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="274" data-original-width="1402" height="123" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8J1he4Mt08burOOL9saAVhJdWSn3uC7dhNzvALWSHA5_nNcCAQoor4Wvrl8Lmy9AI7fkNdkhqTBB5zRsLoOy3bvwSGUTzBOE2RBwZcaPIceXuHbMEVIOWdpnDkxAWxU8J80bbvN6KpQhW/s640/17.bmp" width="640" /></a></div>
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, and <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkWxrkLKtF4lxkPvneoYO3I57b7_MYEA5RWQFLfGzeMgXYm0FV24vbyk9Xhhacb9xe-HvVH4Vt2GKN0lZ0KI6jM5ba54qwwqCx31M7335goRsVet50pIi8IJqmLR8xVnOTg38SeO_KzV1v/s1600/18.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="42" data-original-width="76" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkWxrkLKtF4lxkPvneoYO3I57b7_MYEA5RWQFLfGzeMgXYm0FV24vbyk9Xhhacb9xe-HvVH4Vt2GKN0lZ0KI6jM5ba54qwwqCx31M7335goRsVet50pIi8IJqmLR8xVnOTg38SeO_KzV1v/s1600/18.bmp" /></a>, equation (7.21) can be rewritten as follows:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVqqVgT11pzPRcuHNsv278zIfGomKHmMZC_L1bBFX6Sc3I0TqrZi_YZPabbLPdivpcXfWgVXquRkd-3Qyw-W92FM_YE9_cvSwYOajiAjxdJyYHu42PauNwIwFIKI2ksENBFFzCCitN2hzY/s1600/19.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="179" data-original-width="337" height="169" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVqqVgT11pzPRcuHNsv278zIfGomKHmMZC_L1bBFX6Sc3I0TqrZi_YZPabbLPdivpcXfWgVXquRkd-3Qyw-W92FM_YE9_cvSwYOajiAjxdJyYHu42PauNwIwFIKI2ksENBFFzCCitN2hzY/s320/19.bmp" width="320" /></a>(7.22)</div>
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Below is thermal conductivity of a gas mixture:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1sk3w3_Uv9OJzzSP7PWFCMvaQOFUTz9UVywUeBx3Z_4_-VC_YzCILnkceE6kuaeC-AruOx77arPFoFy_XmpZh7m2bgKzzDlmDlQYmr7ZnqLu31SjKneH59jjiTHoHmvnxppZ_jgZofcN5/s1600/20.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="28" data-original-width="166" height="33" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1sk3w3_Uv9OJzzSP7PWFCMvaQOFUTz9UVywUeBx3Z_4_-VC_YzCILnkceE6kuaeC-AruOx77arPFoFy_XmpZh7m2bgKzzDlmDlQYmr7ZnqLu31SjKneH59jjiTHoHmvnxppZ_jgZofcN5/s200/20.bmp" width="200" /></a><span style="text-align: left;">(7.23)</span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9HZnU26-U9FuuTVMTA3CQT2ThnLSfbb06koj-bcQxiScLLDlBOOSCMzg6KNbbLNUuwOeC6R1o6S9d-yfOQzJ4j3bULX52wT1dOQFaeOfxA0BFtVN9RxgSuN297j3kF96eUPDxziWaXV-Q/s1600/21.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="63" data-original-width="364" height="68" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9HZnU26-U9FuuTVMTA3CQT2ThnLSfbb06koj-bcQxiScLLDlBOOSCMzg6KNbbLNUuwOeC6R1o6S9d-yfOQzJ4j3bULX52wT1dOQFaeOfxA0BFtVN9RxgSuN297j3kF96eUPDxziWaXV-Q/s400/21.bmp" width="400" /></a><span style="text-align: left;">(7.24)</span></div>
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where, the function of velocity of gas stream can be determined as follows:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXhfKDQBe7YGvZQ-_Y9i0lGHibcQu6NB9nzMrYOBjHnF7QJdnnzP-OSDz07Pp4XElTqWW5xKtfkfA5_kBi6t5VVzT1Baziai8QwQxMiSYfDAtqGlUSR8xbbw7op12fs-3ZWvVpocZNoEyt/s1600/22.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="62" data-original-width="205" height="60" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXhfKDQBe7YGvZQ-_Y9i0lGHibcQu6NB9nzMrYOBjHnF7QJdnnzP-OSDz07Pp4XElTqWW5xKtfkfA5_kBi6t5VVzT1Baziai8QwQxMiSYfDAtqGlUSR8xbbw7op12fs-3ZWvVpocZNoEyt/s200/22.bmp" width="200" /></a><span style="text-align: left;">(7.25)</span></div>
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Here we used the following parameters:<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjs4PDnlCMD410XhrECvIRT3yYC6utRXNCLPXdMFtYm47PoaVGkQlB_bfdpoHTYACOMacTuo9CLFGxFKZ4v04rqFJmN1qqGXxBew5YWl8Svs_IChmXPR6MPDQa9crjgvH4pZ2mfTm5QHrxm/s1600/24.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="611" data-original-width="1313" height="296" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjs4PDnlCMD410XhrECvIRT3yYC6utRXNCLPXdMFtYm47PoaVGkQlB_bfdpoHTYACOMacTuo9CLFGxFKZ4v04rqFJmN1qqGXxBew5YWl8Svs_IChmXPR6MPDQa9crjgvH4pZ2mfTm5QHrxm/s640/24.bmp" width="640" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixhRUwIS5ko5BY0vPlRXqy2LPNa2ykrffrjdTqnwlhcOzTsAHa8OVsrILjWroLW8-xQvr5P0n8pWfH8aaBtCkyMMXF68_gA4emooa88snMBFwAQEck66wCDJRO3tz6i3T3ziIYdHG8gVzo/s1600/23.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="667" data-original-width="1353" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixhRUwIS5ko5BY0vPlRXqy2LPNa2ykrffrjdTqnwlhcOzTsAHa8OVsrILjWroLW8-xQvr5P0n8pWfH8aaBtCkyMMXF68_gA4emooa88snMBFwAQEck66wCDJRO3tz6i3T3ziIYdHG8gVzo/s640/23.bmp" width="640" /></a></div>
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The resistance measurements tends to drift with time because of vaporisation of a platinum filament and because of reactions between the filament and the gas under measurement. To reduce this drift glass coatings of the filament are used, but this will reduce the response of the analyser. Sample gas temperature may vary from 1.7 to 43 Deg C, ambient temperature - from -1 to 38 Deg C. For binary gas mixtures an accuracy of thermal conductivity gas analysers is equal +/-2% of full scale.<br />
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<i style="background-color: white; color: #4c4c4c; font-family: arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-31929707506950275012019-04-04T19:17:00.000+05:302019-04-04T19:17:59.408+05:30pH meters (hydrogen ion concentration)<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzvAKS84f-eGnEaZw1XEwi81zVrJ_HUFEy8x5a-9aQ9MN14lX5Y9GvQ4TM4eGjnRjVP5uXo1v2OiASDa4ESBVHd6e08UHzQ5hiQppdXNNWcOELx1Z093_dUallx15G1ErLQjwK0yUAmcsJ/s1600/hi5221.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="1200" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzvAKS84f-eGnEaZw1XEwi81zVrJ_HUFEy8x5a-9aQ9MN14lX5Y9GvQ4TM4eGjnRjVP5uXo1v2OiASDa4ESBVHd6e08UHzQ5hiQppdXNNWcOELx1Z093_dUallx15G1ErLQjwK0yUAmcsJ/s200/hi5221.jpg" width="200" /></a></div>
Acids and bases are significant in food and chemical industries, water and sewage treatment, biology, medicine, etc. Therefore, we need to be able to measure concentration and strength of acid and base solutions. Instrumentation has been developed <b>to measure pH of solutions using special selective electrodes that can develop an electromotive force, which is proportional to the hydrogen ion concentration in the solution where these electrodes are immersed.</b><br /><br />What we understand under the term of <b>pH</b>? How is it related to the concentration and strength of solutions?<br /><br />It is known, that acids and bases produce conductive solutions, when dissolve in water, because charged ions are formed. Here are ionisation equations for hydrochloric acid and sodium hydroxide dissolved in water:<div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikmLr6z6BEe7WKR7v-hfsS7sFr1ysYnIO7jrh08DaQ2zPq-miutXdkbtyD-sZCwb4r0ZoG4CnrQL054lYFNhkC-ejuCQo-wd_i__5MKp9TTdXqa7tciDHo1SMkJ2hVu6n-vM3kg7XNU8YM/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="121" data-original-width="723" height="66" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikmLr6z6BEe7WKR7v-hfsS7sFr1ysYnIO7jrh08DaQ2zPq-miutXdkbtyD-sZCwb4r0ZoG4CnrQL054lYFNhkC-ejuCQo-wd_i__5MKp9TTdXqa7tciDHo1SMkJ2hVu6n-vM3kg7XNU8YM/s400/01.bmp" width="400" /></a></div>
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If we mix these two aqueous solutions, the acidic and basic properties of the solution will be lost, so the neutralisation reaction occurrs:</div>
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<br />Water is formed as the result of this reaction. However, the resulting solution is still conductive, because of the presence of sodium and chloride ions. If the quantities of initial acid and base are equal, then this resultant solution will be neither alkaline, nor acid.<br /><br />In the case of dissociation of pure water, ions of hydrogen and hydroxyl are formed:</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQE4nbTXGo5P152B12JXyo1GhpeJqoyVdAn4WLl4eJ-dgRgeFzHChDTWB74boWmH0PY_P-bnRjgv2Xmd6dA4gNuoHTbjBlipOnEgi2d-o2p7d4C9E0s_9i-7tl4xZpU2UAGt92r-xSbhWo/s1600/03.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="121" data-original-width="856" height="56" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQE4nbTXGo5P152B12JXyo1GhpeJqoyVdAn4WLl4eJ-dgRgeFzHChDTWB74boWmH0PY_P-bnRjgv2Xmd6dA4gNuoHTbjBlipOnEgi2d-o2p7d4C9E0s_9i-7tl4xZpU2UAGt92r-xSbhWo/s400/03.bmp" width="400" /></a></div>
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<span style="text-align: start;">Pure water is very weak regarding </span>to<span style="text-align: start;"> dissociation. So, </span>very<span style="text-align: start;"> small amount of water molecules break into ions. The symbol </span><b style="text-align: start;"><span lang="EN-GB" style="font-family: Symbol; font-size: 14pt;">Û</span></b><span lang="EN-GB" style="font-family: "Times New Roman", serif; font-size: 14pt; text-align: start;"> </span><span style="text-align: start;"> in </span><b style="text-align: start;">(7.4) </b><span style="text-align: start;">indicates that the process consists of two reactions, namely, dissociation of molecules into ions and recombination of ions into molecules. </span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDi8BSCL9P47dq-uMsw9Uc5Aj_R-JRnFhK1ENJWThxzzkd-MyWwuO8sboKLsn1rxbMW6GlA2PSUSPOnCOAyv6yVoxzTkY5frBRi8JM6kgraKXc457HZmIkpUT83afiIVXL2lJuM2OrgZqC/s1600/Dissociation-and-formation-of-hydronium.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="713" data-original-width="1600" height="177" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDi8BSCL9P47dq-uMsw9Uc5Aj_R-JRnFhK1ENJWThxzzkd-MyWwuO8sboKLsn1rxbMW6GlA2PSUSPOnCOAyv6yVoxzTkY5frBRi8JM6kgraKXc457HZmIkpUT83afiIVXL2lJuM2OrgZqC/s400/Dissociation-and-formation-of-hydronium.png" width="400" /></a></div>
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<b>Fig 7.6A :</b> Dissociation and formation of hydronium.</div>
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<span style="text-align: start;">For pure water the rates of these two reactions are equal, and we can write an equilibrium equation as follows:</span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuzsPN2_FgySneBjPmnoAjE-GTEXAkvQuvhJEOcXJVBgn6CjxMZrF5GLTj03g7rm2DbAFnc2IUeABZsdNmLi12Q50k7yJjWzL3byMPclA2hyFWezIt397VnUEd2FSIMDbntnlNpDP_kOFc/s1600/04.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="124" data-original-width="1078" height="45" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuzsPN2_FgySneBjPmnoAjE-GTEXAkvQuvhJEOcXJVBgn6CjxMZrF5GLTj03g7rm2DbAFnc2IUeABZsdNmLi12Q50k7yJjWzL3byMPclA2hyFWezIt397VnUEd2FSIMDbntnlNpDP_kOFc/s400/04.bmp" width="400" /></a></div>
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where,</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTpoR9oD2f4GBiBVAzUrHmvmUwjtd9KKVP8El9SKMLctmz7mvsjieCpytRGXxaNhMnI158Er4uq2VttQspTK8t54tNEsMHKB-OPuJ1QZrV_4DlGRCmssUfDf5h5B9UgM4cFBHp6sEjbwAc/s1600/05.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="187" data-original-width="938" height="78" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTpoR9oD2f4GBiBVAzUrHmvmUwjtd9KKVP8El9SKMLctmz7mvsjieCpytRGXxaNhMnI158Er4uq2VttQspTK8t54tNEsMHKB-OPuJ1QZrV_4DlGRCmssUfDf5h5B9UgM4cFBHp6sEjbwAc/s400/05.bmp" width="400" /></a></div>
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Since pure water is neutral, then according to<b> (7.5)</b> the activity of hydrogen and hydroxyl ions should be equal, ie, <span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">10<span style="mso-text-raise: 5.0pt; position: relative; top: -5.0pt;">-7</span> </span> mole/l. <b>No matter what compounds form an aqueous solution, the product of activities of hydrogen and hydroxyl ions should always be equal to <i><span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">10</span><span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 11.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US; mso-text-raise: 5.0pt; position: relative; top: -5.0pt;">-14</span><span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;"> </span></i> mole/l at 25 °C.</b></div>
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With an addition of a strong acid (such as HCl) to pure water we add many hydrogen ions. As the result of this addition, the number of hydrogen ions will increase, let’s say to <span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">10</span><span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 11.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US; mso-text-raise: 5.0pt; position: relative; top: -5.0pt;">-2</span><span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;"> </span> mole/l, and the activity of hydroxyl ions then will be equal <span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">10<span style="mso-text-raise: 5.0pt; position: relative; top: -5.0pt;">-12</span> </span> mole/l. As we can see, the product of activities is still equal to <i><span lang="EN-GB" style="font-family: "Times New Roman", serif; font-size: 12pt;">10</span><span lang="EN-GB" style="font-family: "Times New Roman", serif; font-size: 11pt; position: relative; top: -5pt;">-14</span><span lang="EN-GB" style="font-family: "Times New Roman", serif; font-size: 12pt; font-weight: bold;"> </span></i> mole/l at 25 °C.<br /><br />Since the use of ion activities in the form of a power representation is not convenient, a Danish biochemist S.P.L. Sørensen in 1909 proposed to use the expression of pH, which was originally derived from the phrase <b>“power of hydrogen”</b>. The pH is defined as a negative common logarithm (with the base of ten) of the hydrogen ion activity, as follows:<br /><br />Therefore, the pH of pure water is equal to 7 at 25 °C. Acid solutions contain more hydrogen ions than hydroxyl ions, so the activity of hydrogen ions will be greater than <span style="font-family: "Times New Roman", serif; font-size: 16px;">10</span><span style="font-family: "Times New Roman", serif; font-size: 16px; position: relative; top: -5pt;">-7</span><span style="font-family: "Times New Roman", serif; font-size: 16px;"> </span>, that is, <span style="font-family: "Times New Roman", serif; font-size: 16px;">10</span><span style="font-family: "Times New Roman", serif; font-size: 16px; position: relative; top: -5pt;">-6</span>, <span style="font-family: "Times New Roman", serif; font-size: 16px;">10</span><span style="font-family: "Times New Roman", serif; font-size: 16px; position: relative; top: -5pt;">-5</span>, <span style="font-family: "Times New Roman", serif; font-size: 16px;">10</span><span style="font-family: "Times New Roman", serif; font-size: 16px; position: relative; top: -5pt;">-4</span>, <span style="font-family: "Times New Roman", serif; font-size: 16px;">10</span><span style="font-family: "Times New Roman", serif; font-size: 16px; position: relative; top: -5pt;">-3</span>, etc., with pH equal to 6, 5, 4, 3, etc., respectively. pH values for basic solutions will be 8, 9, 10, 11, etc., respectively.</div>
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<br />Instrumentation for pH measurements use<b> an electrometric method. A glass pH-responsive electrode</b> immersed in a solution under measurement will vary electric potential (voltage) on the boundary between the electrode and solution as a function of pH of this solution. However, it is not possible to measure the potential between this electrode and solution only. Why? Because when we connect a measuring device, another potential is developed between the solution and a conductor which connects the measuring device and the solution, this new potential being also dependent on the pH of the solution. Therefore, we need to use one more electrode, <b>the reference electrode</b>, which potential is not dependent on the pH of the solution. In order to make the potential of the reference electrode not dependent on the pH of the solution, it should be filled with a saturated solution.<br /><br /><div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3cx18vD69g9QfpTXOs0nkBSx9P2uxsxR1thBvEGHY_qwlu-gKrJlb7xMhn6eszCgmAS74VgFuBozvP-ct8zvgTPbockAGJ782gOIOrcxdiOwPsllAJ4hDbddXeHL8gQ4hSEpXc94SiJAS/s1600/09.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="559" data-original-width="582" height="383" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3cx18vD69g9QfpTXOs0nkBSx9P2uxsxR1thBvEGHY_qwlu-gKrJlb7xMhn6eszCgmAS74VgFuBozvP-ct8zvgTPbockAGJ782gOIOrcxdiOwPsllAJ4hDbddXeHL8gQ4hSEpXc94SiJAS/s400/09.bmp" width="400" /></a></div>
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<b>Figure 7.6.</b> Schematic of a pH-meter with the glass and reference (calomel) electrodes.</div>
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<b>Fig. 7.6</b> shows schematic of a pH-meter. A glass electrode <b>1 </b>and a reference electrode<b> 2</b> are immersed in a solution<b> 3</b> under measurement. The potential difference between these two electrodes which is proportional to the pH of the solution is measured by a potentiometer<b> 6.</b> The glass electrode is filled with the solution <b>4</b> with a known value of pH. A silver-silver chloride electrode<b> 5</b> is placed inside the glass electrode. The reference electrode presents a dielectric enclosure <b>2 </b>filled with pure mercury <b>7</b>. A low soluble mercury-mercury chloride <b>8</b> (calomel) is placed above mercury. The reference electrode is filled with a saturated solution <b>9</b> of KCl. A semipermeable membrane <b>10</b> is used to produce an electrical contact between KCl solution and the solution under measurement 3. Potassium chloride diffuses or leaks into the solution under measurement, so the concentration of KCl in the reference electrode is not changed. An electrical circuit consists of several elements connected in series, and an overall electromotive force is equal to the sum of these potentials, as follows:</div>
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where,<br /><br /><span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">E</span><sub><span lang="EN-GB" style="font-family: Symbol; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-ascii-font-family: "Times New Roman"; mso-bidi-font-family: "Times New Roman"; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-char-type: symbol; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US; mso-hansi-font-family: "Times New Roman"; mso-symbol-font-family: Symbol;">S</span></sub> - the overall electromotive force developed in the circuit, mV;<br /><span lang="EN-GB" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-GB; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">E<sub>1</sub></span> - potential between a silver-silver chloride electrode and the solution<b> 4</b>, mV;<br /><span style="font-family: "Times New Roman", serif; font-size: 16px;">E</span><span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">2</span> - potential between the solution 4 and an internal surface of the glass electrode, mV;<br />E<span style="font-family: Times New Roman, serif;"><span style="font-size: 13.3333px;">3</span></span> - potential between mercury and calomel in the reference electrode, mV;<br />E<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">x</span> - potential between an outside surface of the glass electrode and the solution under measurement, mV.<br /></div>
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E<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">1</span>, E<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">2</span> and E<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">3</span> are not dependent on the pH of the solution under measurement, but vary with temperature. E<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">x</span> depends on the pH of the solution under measurement and its temperature, and can be evaluated by the <b>Nernst equation:</b></div>
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where,<br />R - the gas law constant, R = 8.31451 J/(mole*K);<br />T - absolute temperature of the solution under measurement, K;<br />F - Faraday’s number, F = 96485.309 C/mole, C - coulomb.<br /><br />The overall electromotive force at a constant temperature is the function of the pH of solution only. However, one need to introduce a temperature compensation element (usually a suitable packaged resistor, thermistor, or resistance temperature detector), which is placed close to the glass electrode in the solution under measurement and connected to the electrical circuit for electromotive force measurement.</div>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-57362148375281096892019-04-04T14:54:00.000+05:302019-04-04T14:54:01.234+05:30Electrolytic conductivity meters<div dir="ltr" style="text-align: left;" trbidi="on">
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An operational principle of electrolytic conductivity meters is based on the relationship between electrical conductivity and concentration of solutions.<br /><br />The ability to conduct electricity is called electrical conductance, which is reciprocal of electrical resistance:<br /><br /> <br /><div style="text-align: center;">
<b>electrical conductance = 1/electrical resistance.</b></div>
<br />The unit for electrical conductance is <b><i>Siemens</i></b>: 1S = 1/Ohm.<br /><br />Electrical conductivity is equal to electrical conductance of a volume of the material of unit length and area:<div class="separator" style="clear: both; text-align: center;">
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<b>electrical conductivity = electrical conductance*length/area.</b></div>
<br />The unit for electrical conductivity is <b><i>S/m</i></b>. Few solutions exhibit electrical conductivities as great as 1 S/cm. So, the most commonly used units are <b><i><span lang="EN-GB" style="font-family: Symbol; font-size: 12pt;">m</span>S/cm</i></b> and <b><i>mS/cm.</i></b><br /><br />Electrolytic conductivity is usually defined as electrical conductance of a unit cube of solution as measured between opposite faces. It has the same units as electrical conductivity.<br /><br />In conductive or electrolytic solutions positive ions (cations) move toward the cathode, and negative ions (anions) move toward the anode. Reduction and oxidation take place on the cathode and anode, respectively. Electrolytic conductivity of a solution mostly depends on the concentration and mobility of all ions in the solution. The latter depends on the ion size, charge, dielectric constant of the solvent, temperature and viscosity of the solution. Electrolytic conductivity of a mixture of solutions is proportional to the sum of relative concentration of each components and the mobility of ions. Therefore, conductivity meters are used for electrolytic conductivity measurements of one component solutions only. <b>Fig. 7.4</b> shows typical conductivity curves for NaCl solution in water.<br /><br /><br />Electrolytic conductivity is usually measured by placing electrodes in contact with an electrolytic solution. In this case electrical conductance between electrodes is related to electrolytic conductivity of the solution. Since the conductivity cell has unchanged dimensions, so by measuring electrical conductance of the solution in this cell, and thus determining the cell constant, we can relate thus measured electrical conductance to the actual value of electrolytic conductivity.<br /><br /><br /><b>Fig. 7.5</b> schematically shows an electrolytic conductivity meter, which employs an alternating current Wheatstone bridge in order to avoid polarisation of measuring electrodes. A conductivity cell is immersed in the solution<b> 1</b>. This cell consist of an insulating shield <b>2</b> made of either glass or epoxy, or polystyrene, or Teflon. Two metal electrodes <b>3</b> are placed inside this shield. These electrodes are made of either stainless steel or nickel, or platinum, or gold, or platinum-plated metals. The shield is perforated to provide good contact of solution with these electrodes. The operational principle of a Wheatstone bridge is described in <b>3.5</b>. We measure an electrical resistivity <b>(r)</b> of the electrolytic solution between cell electrodes. An electrical resistivity is defined as an electrical resistance of a conductor of unit cross-sectional area and unit length, as follows: <b>r=R*A/L</b>, (Ohm*m), where, <b>R</b> is the electrical resistance of the conductor (Ohm), <b>A</b> is the cross-section area of the conductor (m2), and<b> L</b> is the length of the conductor (m).<br /><br /><br /><div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhF45-z5R9iOAhwFqOP77ApcKDRfRgSHDfQxKfafuOPDQENuzYihvSGlcev9JndOlcd35wiK-rNEOwSDVSKS-v9np0jOF1N8cIg0DXMvMtIppThEzomNnuZFh-X-TNhX2X-dAJ-dP9lLu0W/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="413" data-original-width="594" height="277" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhF45-z5R9iOAhwFqOP77ApcKDRfRgSHDfQxKfafuOPDQENuzYihvSGlcev9JndOlcd35wiK-rNEOwSDVSKS-v9np0jOF1N8cIg0DXMvMtIppThEzomNnuZFh-X-TNhX2X-dAJ-dP9lLu0W/s400/01.bmp" width="400" /></a></div>
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Figure 7.4. Electrolytic conductivity of NaCl solutions. </div>
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Since temperature of an electrolytic solution has influence on its electrolytic conductivity, therefore, we should be able to introduce temperature correction (compensation). For this purpose an electrode sensor filled with a reference liquid, which has a thermal coefficient of electrolytic conductivity approximately equal to that of the measuring solution, is employed. This sensor is immersed in the measuring electrolytic solution near the measuring conductivity cell, and through conductors is connected to the side of the bridge adjacent to that side of the bridge which is connected to the measuring conductivity cell. Since temperatures of the conductivity measuring cell and the sensor cell are equal, then variations of temperature of the electrolytic solution will not have influence on the results of electrolytic conductivity measurements.<div style="text-align: center;">
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Figure 7.5. Electrolytic conductivity meter.</div>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px; text-align: left;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-65793725583405263862019-03-05T19:10:00.000+05:302019-04-04T14:25:45.725+05:30On-line chromatographic analysis<div dir="ltr" style="text-align: left;" trbidi="on">
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As early as 1903-1906 a Russian botanist Mikhail Tsvet (Lecturer in the Warsaw University) performed experiments trying to separate pigments of plants. Using a solvent, petroleum ether, he washed the pigments through a vertical glass tube filled with a powder-like absorbent, calcium carbonate. As the result of this procedure, he obtained a series of coloured absorption bands. He first used a term ‘chromatography’ to describe this method. Word ‘chromatography’ consists of two words ‘chromatos’ (in Greek language means ‘colour’) and ‘grapho’ (in Greek language means ‘writing’), and means ‘colour writing’. By coincidence, the surname ‘Tsvet’ in Russian language means ‘colour’.<br />
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Chromatography methods are classified regarding to the types of moving and stationary phases according to Figure 7.1.<b> (from Considine D. M. Process Instruments and Controls Handbook. McGraw-Hill Book Company, Sydney, 1985, p. 6.170).</b><br />
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<b>Figure 7.1. Classification of chromatography methods. </b></div>
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<u>Physical absorption principles for separating of various components from a mixture of chemical substances form the basis of chromatography</u> <b>(see Fig. 7.2)</b>. A gas mixture <b>1</b> to be analysed is carried through a tube or column <b>2</b> by an inert carrier gas (nitrogen, helium)<b> 3</b>. The gas mixture and the carrier gas form <i><u>the moving phase</u></i>. The column is filled (packed) with materials<b> 4,</b> <u><i>the stationary phase</i></u>, which will absorb gases. Different components of the gas mixture are delayed for varying increments of time. After the column, the separated gases <b>5</b> pass through a gas detector (flame ionisation detector, or thermal conductivity detector) <b>6</b>. This detector develops a signal <b>7</b>, which then is transformed to the chromatogram <b>8.</b> Using this chromatogram we can determine the type of a component and its quantity. In order to achieve better separation of components from various mixtures different types of packing materials should be chosen. The absorption of components by the stationary phase is highly dependent on the operational conditions. Therefore, temperature, flowrate and pressure of a carrier gas, sample valve timing, and detector sensitivity should be carefully controlled.<br />
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Chromatographs are widely used for composition measurements of gaseous and liquid mixtures. Usually they are complex laboratory equipment. Modern on-line chromatography systems for continuous, repetitive and fully automatic gas analysis have been developed, and in principle have all essential elements inherent to laboratory-type equipment. <b>Fig. 7.3</b> schematically shows an operational principle of an on-line gas-chromatograph.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtcioIBhps6rDfbUBRj511hDa7is7zBkHpyhtLK7-_Vz5xIed_FfmkNM69V7As6RLVLHjL9TNVpauzXwFaayxtariz2eg6sGf_pFoJ9OCz1X3m5EbA8NLd1KXHhSH9MvF3zfs7d907AMXc/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="645" data-original-width="1215" height="337" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtcioIBhps6rDfbUBRj511hDa7is7zBkHpyhtLK7-_Vz5xIed_FfmkNM69V7As6RLVLHjL9TNVpauzXwFaayxtariz2eg6sGf_pFoJ9OCz1X3m5EbA8NLd1KXHhSH9MvF3zfs7d907AMXc/s640/01.bmp" width="640" /></a></div>
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<b>Figure 7.2</b>. Schematic of a gas-chromatograph (gas-solid chromatography). </div>
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A sample of a gas mixture <b>1</b> is withdrawn continuously from a process unit <b>2 </b>and through a shutoff valve <b>3,</b> filter <b>3a</b> (for removing of particulate matter) and pressure regulator<b> 4</b> (for reducing pressure to a lower constant value) circulates through a sample conditioning unit <b>5</b>. After the sample conditioning unit the stream enters the process <b>6 </b>through a shutoff valve <b>7 </b>in the point of a lower pressure compared with the sample withdrawal point. The sample conditioning unit allows to calibrate the gas-chromatograph with the synthetic calibration blend from a container <b>8,</b> through a pressure regulator <b>9</b>, and to control flowrate. A carrier gas (nitrogen, helium) is supplied from a cylinder <b>10,</b> and its pressure is controlled by a pressure regulator <b>11</b> and a pneumatic control section <b>12.</b> An analyser <b>13</b> contains separating columns, flame ionisation and/or thermal conductivity detector(s) and a temperature control unit. A metering pump, which is placed in the sample conditioning unit, injects a small sample of an already conditioned gas mixture into the separating column, which is placed in the analyser. An electronic module <b>14</b> stores analytical programs in RAM and controls functions of the analyser. Analytical data are transferred from the electronic module to a data processor <b>15</b>, where they are converted to analog signals. These signals are transmitted to a bar graph recorder<b>16</b> and a number of trend recorders<b> 17</b>. A host computer <b>18 </b>controls all actions of the chromatograph, receives results, alarm messages, stores application programs. A real-time chromatogram is printed on the printer <b>19</b>. </div>
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Here are several values of parameters of a chromatograph:</div>
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<li>temperature in the temperature control unit - 40 to 200 °C;</li>
<li>accuracy of temperature control - ±0.2 °C;</li>
<li>total length of separating columns - 10 m;</li>
<li>diameter of separating columns - 3 mm;</li>
<li>flowrate of a carrier gas - 40 to 160 cm<sup><span lang="EN-GB" style="font-family: "times new roman" , serif;"><span style="font-size: x-small;">3</span></span></sup>/min;</li>
<li>volumes of samples of gas mixtures - 0.5, 1, 2, 4 cm<sup><span lang="EN-GB" style="font-family: "times new roman" , serif;"><span style="font-size: x-small;">3</span></span></sup>;</li>
<li>volumes of samples of liquid mixtures - 0.004, 0.008, 0.032 cm<sup><span lang="EN-GB" style="font-family: "times new roman" , serif;"><span style="font-size: x-small;">3</span></span></sup>;</li>
<li>pressure of a gas carrier - 400 kPa;</li>
<li>output signal - 4 to 20 mA.</li>
</ul>
An output signal from a gas-chromatograph is usually used as an input signal for a controller, which changes either process temperature or pressure or flowrate, etc., to bring a product composition to the desired value.<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJNGoD98Zul_-X2RC6vIuitOhf3nzqLZbea70WKNNBi2tvV8TtC_6P2jscNSYPw8VHGYZAXTf4McBZNMP6PAa71Qy-QCqyXUTEZ-tVMD8yA4EgwbAz1XJRkE6QIzVSB8AL4yox5Me7LxTY/s1600/02.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="170" data-original-width="627" height="172" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJNGoD98Zul_-X2RC6vIuitOhf3nzqLZbea70WKNNBi2tvV8TtC_6P2jscNSYPw8VHGYZAXTf4McBZNMP6PAa71Qy-QCqyXUTEZ-tVMD8yA4EgwbAz1XJRkE6QIzVSB8AL4yox5Me7LxTY/s640/02.bmp" width="640" /></a><br />
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<b>Figure 7.3.</b> On-line chromatographic system.</div>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px; text-align: left;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-67767380249108756212019-03-05T18:36:00.001+05:302020-05-03T23:05:51.454+05:30Instrumentation for analytical measurements<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgl1jszD91YbeLqCMgSwyuDwUAcUu2OO0tMlW62QtlsdhvseGNE05H1NmTruB3whdyzsISJonh8yP-F3e2Psk0XnmjjczkE8Hsi5TaJed49arq-cvji3INa-hQ3bjVDCEcbLvlUEB9T_wvf/s1600/02.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="768" data-original-width="1024" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgl1jszD91YbeLqCMgSwyuDwUAcUu2OO0tMlW62QtlsdhvseGNE05H1NmTruB3whdyzsISJonh8yP-F3e2Psk0XnmjjczkE8Hsi5TaJed49arq-cvji3INa-hQ3bjVDCEcbLvlUEB9T_wvf/s320/02.jpg" width="320" /></a></div>
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With instrumentation used for analytical measurements in process environment we are able to define the content of chemical streams. So we can control the composition of intermediate and final products. Analytical instrumentation may be classified regarding to the measuring method employed, as follows:<br />
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Physical: </h4>
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<ol>
<li>Gas and liquid chromatography; </li>
<li>Infrared analysers; </li>
<li>Ultraviolet analysers; </li>
<li>Turbidimeters; </li>
<li>Densimeters; </li>
<li>Viscometers;</li>
</ol>
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Electrochemical: </h4>
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<ol>
<li>Electrolytic conductivity meters</li>
<li>pH meters (hydrogen ion concentration).</li>
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Operational principles of analytical instruments are based on the interactions between energy and matter. Matter is made of complex arrangements of particles. Each particle has its mass, electrical charge, or is neutral. Neutrons (with mass, but without electrical charge) and protons (with mass almost equal to that of a neutron and with a unit positive charge) form the nuclei of atoms, and determine their atomic weight, and chemical and physical properties of substance. Chemical properties are also characterized by the number of electrons (with negligible mass and with a unit negative electric charge) and their energy state. If we can observe the results of interaction (change of the energy state of electrons) between these electrons and energy from external source, then we will be able to obtain information about the composition of a particular substance. Among types of energy we can mention electromagnetic radiation, chemical reactivity, electric and magnetic fields, thermal and mechanical energy.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhb1xhtSisMC1pEnR_Jq7WFYHC4M1K7470H3Wo1t8TCY61CpL2RhLn0X1q_BjhepcM94QioDHSiMNHJvz5gMehYAYn8JBUrT-o5N6jWS6FilM5WuLUqpPPkQCwwteoHhkqJeQarZu1hX3Hp/s1600/01.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="400" data-original-width="680" height="376" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhb1xhtSisMC1pEnR_Jq7WFYHC4M1K7470H3Wo1t8TCY61CpL2RhLn0X1q_BjhepcM94QioDHSiMNHJvz5gMehYAYn8JBUrT-o5N6jWS6FilM5WuLUqpPPkQCwwteoHhkqJeQarZu1hX3Hp/s640/01.jpg" width="640" /></a></div>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;"><span style="font-family: Arial, sans-serif; font-size: 12.8px; font-style: normal; line-height: 19.1875px; margin: 0px; padding: 0px; text-align: left;"><span style="font-family: Verdana, sans-serif; margin: 0px; padding: 0px;">The links below will explain the instrumentation for analytical measurements in detail :</span></span></span></span></i><br />
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<li><i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;"><span style="font-family: Arial, sans-serif; font-size: 12.8px; font-style: normal; line-height: 19.1875px; margin: 0px; padding: 0px; text-align: left;"><span style="font-family: Verdana, sans-serif; margin: 0px; padding: 0px;"><a href="http://aboutinstrumentation.blogspot.com/2019/03/on-line-chromatographic-analysis.html" style="color: #cc0000; font-family: Arial, sans-serif; font-size: 12.16px; margin: 0px; padding: 0px; text-align: justify;">On-line chromatographic analysis</a></span></span></span></span></i></li>
<li><i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;"><span style="font-family: Arial, sans-serif; font-size: 12.8px; font-style: normal; line-height: 19.1875px; margin: 0px; padding: 0px; text-align: left;"><a href="http://aboutinstrumentation.blogspot.com/2019/04/electrolytic-conductivity-meters.html" style="color: #cc0000; font-size: 12.16px; margin: 0px; padding: 0px; text-align: justify;">Electrolytic conductivity meters</a></span></span></span></i></li>
<li><i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;"><a href="http://aboutinstrumentation.blogspot.com/2019/04/ph-meters-hydrogen-ion-concentration.html" style="color: #cc0000; font-family: Arial, sans-serif; font-size: 12.16px; font-style: normal; margin: 0px; padding: 0px;">pH meters (hydrogen ion concentration)</a></span></span></i></li>
<li><i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><a href="http://aboutinstrumentation.blogspot.com/2020/05/thermal-conductivity-gas-analysers.html" style="color: #cc0000; font-family: Arial, sans-serif; font-size: 12.16px; font-style: normal; margin: 0px; padding: 0px; text-align: justify;">Thermal conductivity gas analysers</a></span></i></li>
<li><i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><a href="http://aboutinstrumentation.blogspot.com/2020/05/flame-ionisation-detectors-analysers.html" style="color: #cc0000; font-family: Arial, sans-serif; font-size: 12.16px; font-style: normal; margin: 0px; padding: 0px; text-align: justify;">Flame ionisation detectors (analysers)</a></i></li>
<li><a href="http://aboutinstrumentation.blogspot.com/2020/05/turbidity-meters.html" style="background-color: white; color: #cc0000; font-family: Arial, sans-serif; font-size: 12.16px; margin: 0px; padding: 0px; text-align: justify;">Turbidity meters</a></li>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms" , sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-38894470947587966122019-02-19T15:30:00.000+05:302019-02-19T15:30:35.270+05:30Ultrasound flowmeters<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiawzF6DXDxtm0dp25UkGU-9NLnNgiK1j1JqnKvRemLGCCeVy_bYLBVErEUfysWdx3dW5Y6Ay1b7fXSrHdsLb5tr9sfiao7yOoVvhY3W8TuBb1lmVqk_POKw34OkKbjSsNiBbr7gRAiSU_b/s1600/ultrasonic-flowmeters-500x500.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="332" data-original-width="378" height="281" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiawzF6DXDxtm0dp25UkGU-9NLnNgiK1j1JqnKvRemLGCCeVy_bYLBVErEUfysWdx3dW5Y6Ay1b7fXSrHdsLb5tr9sfiao7yOoVvhY3W8TuBb1lmVqk_POKw34OkKbjSsNiBbr7gRAiSU_b/s320/ultrasonic-flowmeters-500x500.jpg" width="320" /></a></div>
This method is based on the relationship between the flowrate of the stream and the velocity of ultrasound introduced in this stream. There are several modifications of this method, such as Doppler-effect method and transit-time method. The first one is based on the Doppler effect, saying that frequencies of received waves are dependent on the motion of the source or receiver (observer) relative to the propagating medium. We will describe the second method, which is shown schematically in <b>Fig 6.6.</b><div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-MsqaiD_ATZJmA5ODD8502FdpMAw9kdsOomMzvCIAuV8lP4m1xlxkRsbcGtrb8SqiyHZ2LA0KGj6YMNBT3NEDVLqn2wM5S2vzIjZsKGXmlzevt19AsUz8CQz_0RE8NaCV8KkP4tbvxL50/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="380" data-original-width="625" height="242" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-MsqaiD_ATZJmA5ODD8502FdpMAw9kdsOomMzvCIAuV8lP4m1xlxkRsbcGtrb8SqiyHZ2LA0KGj6YMNBT3NEDVLqn2wM5S2vzIjZsKGXmlzevt19AsUz8CQz_0RE8NaCV8KkP4tbvxL50/s400/01.bmp" width="400" /></a></div>
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Figure 6.6. Transit-time flowmeter.</div>
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<br /><br />A source of ultrasound<b> 1</b> is attached outside to the pipe <b>2 </b>with a flowing fluid <b>3</b> inside it. A sonic beam is propagating the flowing fluid at a specific velocity, proportional to the properties of the fluid (temperature, pressure, and density). An ultrasound beam <b>4 </b>will travel faster in the direction of flow, and slower in the opposite direction. This beam arrives in to the receiver <b>5</b> faster than an ultrasound beam <b>6</b> from the transmitter <b>7</b> to the receiver <b>8. </b><br /><br /> <br />Transit time of ultrasound beam from transducer the <b>1</b> to the receiver <b>5</b> can be evaluated as follows (<b>from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 411-412</b>):<div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicvj7SoHSfuJMIUcZFJZOaz7itPTpcDssttBTTaI5UNlZxg9Nx-BwrqdEbvqOGUplls7wsJXWfU1XBKsbHlenzDpqGSI0uv_NcLC9VLkgkjQqF3wruQ5Bx20vz6Al4h7jjI2yrH2AjeR0h/s1600/02.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="70" data-original-width="141" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicvj7SoHSfuJMIUcZFJZOaz7itPTpcDssttBTTaI5UNlZxg9Nx-BwrqdEbvqOGUplls7wsJXWfU1XBKsbHlenzDpqGSI0uv_NcLC9VLkgkjQqF3wruQ5Bx20vz6Al4h7jjI2yrH2AjeR0h/s1600/02.bmp" /></a>(6.46)</div>
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Transit time of ultrasound beam from the transducer <b>7</b> to the receiver<b> 8</b> can be evaluated as follows:<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdmnukgdkpz_SXetTvVl4UdMzNMPUo25Q9jHqE13-dCWWnjemi6kGShbUVhRQNW6mnq9nqGCYkCz8B-KvNl0NoiOPXNFVDUC8RSr6_6tPHBxpzmiuXvc6_A45En72d5Orce9FGbgui31r8/s1600/03.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="54" data-original-width="129" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdmnukgdkpz_SXetTvVl4UdMzNMPUo25Q9jHqE13-dCWWnjemi6kGShbUVhRQNW6mnq9nqGCYkCz8B-KvNl0NoiOPXNFVDUC8RSr6_6tPHBxpzmiuXvc6_A45En72d5Orce9FGbgui31r8/s1600/03.bmp" /></a>(6.47)</div>
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<div class="MsoNormal" style="text-align: justify;">
<span lang="EN-AU" style="font-size: 12.0pt; mso-bidi-font-size: 10.0pt;">Let’s evaluate the time
difference:<o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6C35p3BCj-SnnnOMwCUTkUFOYAp0dIoPTeIFtX25x8Conrx2Cy-I7agXD4dlrxm1FIZ_7GGT6TMs3L-S2C2KPPZfvJfyc9gsEvEZaUGCXl4rKBa-H_ShZCM33anW-PTF8GvLvt1M7GyKQ/s1600/04.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="172" data-original-width="357" height="154" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6C35p3BCj-SnnnOMwCUTkUFOYAp0dIoPTeIFtX25x8Conrx2Cy-I7agXD4dlrxm1FIZ_7GGT6TMs3L-S2C2KPPZfvJfyc9gsEvEZaUGCXl4rKBa-H_ShZCM33anW-PTF8GvLvt1M7GyKQ/s320/04.bmp" width="320" /></a>(6.48)</div>
<br />The ratio <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyLgDrXPUIK5naWoAI6jgQoyNBCU2xjhaAZ2CGd_j7ogieBhDsH-sXcWcXppS1b65Sj1fOtEJa13ZAH19uuMD2FmlLTdttmDkYVhQ_ImHmvkZwseMJmLqPF1e_7XOm55NZOxFgTJDpbn0Q/s1600/05.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="51" data-original-width="81" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyLgDrXPUIK5naWoAI6jgQoyNBCU2xjhaAZ2CGd_j7ogieBhDsH-sXcWcXppS1b65Sj1fOtEJa13ZAH19uuMD2FmlLTdttmDkYVhQ_ImHmvkZwseMJmLqPF1e_7XOm55NZOxFgTJDpbn0Q/s1600/05.bmp" /></a><span style="text-align: center;">, therefore,</span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO2JBfLiicAEvTiqBykAECDCefM0TItIic5nAqJKHUemqpGg6HAx5nyySLPJIHoKp5SRxG2FXEgjtCVq8JbeOargRKoWWuLqeA-0sQVCfL3T6KKjIEyNBNFGToPAx2HGMbLDA4wI4QwHje/s1600/06.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="53" data-original-width="113" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO2JBfLiicAEvTiqBykAECDCefM0TItIic5nAqJKHUemqpGg6HAx5nyySLPJIHoKp5SRxG2FXEgjtCVq8JbeOargRKoWWuLqeA-0sQVCfL3T6KKjIEyNBNFGToPAx2HGMbLDA4wI4QwHje/s1600/06.bmp" /></a>(6.49)<br /><br /><br />Using <b>(6.49)</b> we can reduce <b>(6.48)</b> to the following form:<div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaOpYUArrx7UNZh_TR36Uo2N34iopdEKP7haePBEULA3DeNeK8qQeabxRd3hgER8jsMV-UlyR32w51BvlMN7luA_szjBZBzGuqIN9NahZBQ_0ol1p8ba1pvK43NJkIExlF0DUIcdG4kALg/s1600/07.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="53" data-original-width="129" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaOpYUArrx7UNZh_TR36Uo2N34iopdEKP7haePBEULA3DeNeK8qQeabxRd3hgER8jsMV-UlyR32w51BvlMN7luA_szjBZBzGuqIN9NahZBQ_0ol1p8ba1pvK43NJkIExlF0DUIcdG4kALg/s1600/07.bmp" /></a>(6.50)</div>
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where, </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiV7Np4PpwEKann48XVPWzVoW0-Ai72lfREzD9muinu1_gHNgCZakPHbFJIkYxUmxMa407s9HELhRfjlPTpzraPVE6G37MOiN5lVpo48vBZdxUvzV24wAJoiNtVHUQJr6G2bKnV2cvQbKN4/s1600/08.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="331" data-original-width="875" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiV7Np4PpwEKann48XVPWzVoW0-Ai72lfREzD9muinu1_gHNgCZakPHbFJIkYxUmxMa407s9HELhRfjlPTpzraPVE6G37MOiN5lVpo48vBZdxUvzV24wAJoiNtVHUQJr6G2bKnV2cvQbKN4/s400/08.bmp" width="400" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTGTtP448lixOCEtI7JtwkdYCN-2b4hlih39NzGQj-cN0YaD2n2vGgk7OFU_xhlGzSqATXZbu6rZ0E6ZkEcxPtspxsSFUR9qKaduE8pmV5BL1tdUWfjzOMpZrrVysC_gPMHO6gpy3K9I7I/s1600/09.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="199" data-original-width="1111" height="71" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTGTtP448lixOCEtI7JtwkdYCN-2b4hlih39NzGQj-cN0YaD2n2vGgk7OFU_xhlGzSqATXZbu6rZ0E6ZkEcxPtspxsSFUR9qKaduE8pmV5BL1tdUWfjzOMpZrrVysC_gPMHO6gpy3K9I7I/s400/09.bmp" width="400" /></a></div>
<br /><br />These devices can not be used for flow measurements of fluids with air bubbles or solid particles, since they will interfere with the transmission and receipt of ultrasound radiation. These particles serve as reflectors of ultrasound radiation.<div>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-30236834837784918892019-02-19T14:59:00.001+05:302019-02-19T14:59:33.109+05:30Turbine flowmeters<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUSTEGAfB_kdPBTd3X6BhFyk72BRYUCvvK3oNTPNhbV4Po2yek0IuI5zfd3SNxM7zSu1wK5AQHyaTsfFw8VfEzwte4NUgv-RG2gkmt6_WjXveDaWSCOavvJ0xgnKKAr5M0RgBMdTeZ4RS2/s1600/turbine-flow-meter-500x500.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="500" data-original-width="500" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUSTEGAfB_kdPBTd3X6BhFyk72BRYUCvvK3oNTPNhbV4Po2yek0IuI5zfd3SNxM7zSu1wK5AQHyaTsfFw8VfEzwte4NUgv-RG2gkmt6_WjXveDaWSCOavvJ0xgnKKAr5M0RgBMdTeZ4RS2/s200/turbine-flow-meter-500x500.jpg" width="200" /></a></div>
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These flowmeters refer to velocity measurement devices, since the action (rotation) of their measuring element (turbine) is proportional to stream velocity, which, in its turn, is proportional to the flow of fluid in the pipe. Turbine flowmeters provide accurate measurements in the wide flow range. However, their application is limited to clean liquids. The name of this device comes from the operational principle of this flowmeter <b>(see Fig. 6.5).</b> <div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcggxwYjTuz5VUNCChKuoIKTnZhlTRo-5CgKRDcVAlBL3cAxIp4LzhZSCgZD4IdpSBLOrHSw8-SvpyuGYJ2lRJCwfRj8xf_AmYQROptIPSppkO1MLJzi_vkGSJ17jALBiDWGB_IKvPdDZm/s1600/daniel-series-1500-exploded-drawing-needs-crop-data-179340.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="1183" data-original-width="1600" height="472" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcggxwYjTuz5VUNCChKuoIKTnZhlTRo-5CgKRDcVAlBL3cAxIp4LzhZSCgZD4IdpSBLOrHSw8-SvpyuGYJ2lRJCwfRj8xf_AmYQROptIPSppkO1MLJzi_vkGSJ17jALBiDWGB_IKvPdDZm/s640/daniel-series-1500-exploded-drawing-needs-crop-data-179340.jpg" width="640" /></a></div>
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Fig . 6.5A Basic Parts of the turbine flow meter</div>
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<br /><br />The housing of this device<b> 1</b> is connected to pipes <b>2</b> and <b>3</b>. A turbine <b>4</b>, sometimes called a rotor, is placed co-axial in this housing in the path of the flowing liquid. This liquid imparts the force to the blades <b>5</b> of the rotor and causes the rotor to rotate on the shaft <b>6</b>, which is connected with the housing by a support <b>7</b> with bearings. In order to straighten the stream of the passing fluid, several radial-straightening vanes <b>8 </b>are placed on the shaft before the rotor in upstream direction. The rotational speed of the rotor is proportional to the fluid velocity only when a steady rotational speed of the rotor has been reached. If we measure the number of turbine wheel revolutions per unit time, then this will be a measure of flowrate. Therefore, we need to measure the number of rotor revolutions. Several methods are used to transmit rotor revolutions through the meter housing to the readout device, which is placed outside the housing. The first method employs a mechanical device, which by use of selected gear trains <b>9</b> transmits the rotation of the turbine directly to the register <b>10.</b> Another, electrical method, employs a permanent magnet with several coils mounted close to the rotor but external to the fluid channel. When one blade of the rotor passes the coil, the total flux through the coil changes and a pulse of voltage is generated (one cycle of voltage). The frequency of voltage pulses is proportional to the fluid flowrate, and the total number of pulses is an indicator of the total flow. <br /><br /> <div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6YDH4t2LAOGpP_GWjBY-79R7nNweyiq8-WzxQyDcdl0EowHiBR7Topyl1caIbzFr3gCMg31Vso2o6yqGpnDtu8P7jDWZvhk81Dq-L1mp6-6Io-54szQRMa3xbvkAdY8kIUvBvdwt2Dlu4/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="408" data-original-width="612" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6YDH4t2LAOGpP_GWjBY-79R7nNweyiq8-WzxQyDcdl0EowHiBR7Topyl1caIbzFr3gCMg31Vso2o6yqGpnDtu8P7jDWZvhk81Dq-L1mp6-6Io-54szQRMa3xbvkAdY8kIUvBvdwt2Dlu4/s400/01.bmp" width="400" /></a></div>
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Figure 6.5. Turbine flowmeter.</div>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-15480614060347256262019-02-19T14:45:00.000+05:302019-02-19T14:45:18.196+05:30Venturi flow nozzle<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJIm3IjGcYYn4KT6u5nuBimBixYxPCbRgqyVnVLlYdoo6AvM8GjIMGLP57wXOTnrjGbelT68kWqdAmgLve0Ufe-XonLTjj3PQ2b7waeZN9EDdh9cLOc6pfLKNWjnjjdoPR9V0noo0L6Pig/s1600/81505-11888947.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="600" data-original-width="600" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJIm3IjGcYYn4KT6u5nuBimBixYxPCbRgqyVnVLlYdoo6AvM8GjIMGLP57wXOTnrjGbelT68kWqdAmgLve0Ufe-XonLTjj3PQ2b7waeZN9EDdh9cLOc6pfLKNWjnjjdoPR9V0noo0L6Pig/s200/81505-11888947.jpg" width="200" /></a></div>
There is another modification of the variable differential pressure technique for flowrate measurements. This technique employs a Venturi flow nozzle, which is shown schematically in <b>Fig. 6.4. </b><br /><br /><br />The Venturi flow nozzle is installed in pipes with internal diameter varying from 65 to 500 mm. It produces a large differential pressure with a minimum loss of static pressure. This nozzle is able to measure flowrates of fluids with suspended solids. However, Venturi flow nozzles are very expensive. It consists of three parts: a profiled inlet <b>1</b>, a cylindrical throat <b>2</b>, and a conical outlet <b>3</b>. A pipes <b>4</b> and <b>5</b> are connected to the inlet and outlet of the Venturi flow nozzle. The nozzle may be long and short. In the first case the biggest diameter of the outlet cone <b><span lang="EN-AU" style="font-family: "Times New Roman", serif; font-size: 12pt;">D<sub>c</sub><sup>max</sup></span></b> is equal to the internal diameter of the pipe <span style="font-family: "Times New Roman", serif; font-size: 12pt;"> <b><span lang="EN-AU">D<sub>p</sub></span></b></span>, in the second case it is less than <b style="font-family: "Times New Roman", serif; font-size: 16px;"><span lang="EN-AU">D<sub>p</sub></span></b>. The restriction diameter of Venturi flow nozzles <b><span lang="EN-AU" style="font-family: "Times New Roman", serif; font-size: 12pt;">D<sub>n</sub> </span><span lang="EN-AU" style="font-family: Symbol; font-size: 12pt;">³</span><span lang="EN-AU" style="font-family: "Times New Roman", serif; font-size: 12pt;"> </span></b>15 mm. The differential pressure is measured as in the case for orifice flowmeters with the only difference, that the downstream pressure in the cylindrical throat is sensed through radially drilled holes<b> 6.</b><br /><div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpGrXK5V8bkTMgr0xukyKRa9pVl_SNyw-kYMjf7__NbTTrY8KNxqJs9xAGAnHw2eOzV0KfGKMA9-9hfmq5UDeHzZBvKBsUB5GCBARAatG7faUrqx6BE2mfUBNEjoaJdyCRfq50-p1FtGsZ/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="387" data-original-width="600" height="257" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpGrXK5V8bkTMgr0xukyKRa9pVl_SNyw-kYMjf7__NbTTrY8KNxqJs9xAGAnHw2eOzV0KfGKMA9-9hfmq5UDeHzZBvKBsUB5GCBARAatG7faUrqx6BE2mfUBNEjoaJdyCRfq50-p1FtGsZ/s400/01.bmp" width="400" /></a></div>
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<b>Figure 6.4. </b>Venturi flow nozzle.</div>
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<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-54356785720272711672019-02-16T19:20:00.002+05:302019-02-16T19:20:33.076+05:30Rotameters<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1Xwx-qRKp2ke4lhs0Jaw4FA5qzTY8qVlOaImT6YFc2g83lXBccqe5ItsqYxSQsoe-bxNfeQk-ycFr8o5PsfySbpVtxnwlk1jF627eHwgWA6YhAeICRsrV2amQoVOjESWtchJbujWrdgpw/s1600/fig1.gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="292" data-original-width="270" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1Xwx-qRKp2ke4lhs0Jaw4FA5qzTY8qVlOaImT6YFc2g83lXBccqe5ItsqYxSQsoe-bxNfeQk-ycFr8o5PsfySbpVtxnwlk1jF627eHwgWA6YhAeICRsrV2amQoVOjESWtchJbujWrdgpw/s200/fig1.gif" width="184" /></a>This type of device <b>(see Figure 6.3)</b> consists of a vertical tapered tube <b>1</b> (usually made of a glass or other transparent material) and a rotor <b>2</b> (or a float), usually made of a metal (aluminium, brass, stainless steel, etc.) with higher density than that of a fluid 3 being measured. </div>
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The rotor is produced with slots to give it rotation, so the rotor can be placed co-axial inside the tube. When the flowrate of the fluid through the tube increases the rotor is elevated upwards until the balance between forces acting on the rotor is achieved. Since the tube is tapered, then the restriction area (the area between the wall of the tube and side surface of the float) will change to accommodate flow rate being measured. Therefore, for each value of the flowrate will correspond certain position of the rotor in the tube in respect to a scale 4 and a certain value of the restriction area. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWc4IQEuoGJ99vzI4StyKpaRSjd7b6koymlcEJoM7Bg82zwUSIFgCI9y8m7lm6J7Mz2Uzs0sekUC62wO139vh0ECpWCTlBdzVR-8o-ZHHx9VYX5zdLl7xeMrlw39pNUY7_sy2NCI3Was1P/s1600/05.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="514" data-original-width="589" height="279" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWc4IQEuoGJ99vzI4StyKpaRSjd7b6koymlcEJoM7Bg82zwUSIFgCI9y8m7lm6J7Mz2Uzs0sekUC62wO139vh0ECpWCTlBdzVR-8o-ZHHx9VYX5zdLl7xeMrlw39pNUY7_sy2NCI3Was1P/s320/05.bmp" width="320" /></a></div>
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<b>Figure 6.3. </b>Variable area flowmeter (rotameter).</div>
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<br />Let's consider forces acting on the rotor during balance:<div class="separator" style="clear: both; text-align: center;">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGobC6FXDNSwgrtdCC_-dmUnarmcMVaV0gI4ljE6ug256aUeRRQ45wTNe0wBooLKDmS5Gb4V3Iqey_xRjPNpupuYoDOLoIq4umW16clWCSOPJtjHsW0gPj7xUmcUlwpJUYt_7pPwUUXksk/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="29" data-original-width="126" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGobC6FXDNSwgrtdCC_-dmUnarmcMVaV0gI4ljE6ug256aUeRRQ45wTNe0wBooLKDmS5Gb4V3Iqey_xRjPNpupuYoDOLoIq4umW16clWCSOPJtjHsW0gPj7xUmcUlwpJUYt_7pPwUUXksk/s1600/01.bmp" /></a> (6.40)</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCHWDiFswTKSMD4ci9xhTEfmR6hswQV6F3XTkWCwuPDOcBG77v2CA9_xhz4NTwPCNe9JjQfuUh1cVDnHxGrP3eLMkoIkO8Dkuvlu_I7wDE6oBamjvHvxHuo0c-Hfvk6M9MwZUnO6bdOZFw/s1600/02.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="33" data-original-width="244" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCHWDiFswTKSMD4ci9xhTEfmR6hswQV6F3XTkWCwuPDOcBG77v2CA9_xhz4NTwPCNe9JjQfuUh1cVDnHxGrP3eLMkoIkO8Dkuvlu_I7wDE6oBamjvHvxHuo0c-Hfvk6M9MwZUnO6bdOZFw/s1600/02.bmp" /></a>(6.41)</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjgorrUils76MTthUo0x-lHdLFevwphhSHDYAgw2tAjvWNAYk7NZhpDyb-6XI1If6ytmLRgGo1WHKXxEOE_HTtM2YeLRB3emuxYw1ygKHrNnrYOPT8ZLBzLNbBUc3f2VW_dGNPJawAek7R/s1600/03.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="33" data-original-width="244" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjgorrUils76MTthUo0x-lHdLFevwphhSHDYAgw2tAjvWNAYk7NZhpDyb-6XI1If6ytmLRgGo1WHKXxEOE_HTtM2YeLRB3emuxYw1ygKHrNnrYOPT8ZLBzLNbBUc3f2VW_dGNPJawAek7R/s1600/03.bmp" /></a>(6.42)</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4Se09i9TB2gwjKadeg8hpG9vElgmt23QAgl3iwguQCLhgLNgPSSACl7mtoyhNDwvkGGlJQcfSUebysJdzX4BgnZbIuMdgHkefXCF0Uh6tcmPo_YunnZJbaNMmeFRxYVdCVxyyeVgHpprX/s1600/04.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="57" data-original-width="258" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4Se09i9TB2gwjKadeg8hpG9vElgmt23QAgl3iwguQCLhgLNgPSSACl7mtoyhNDwvkGGlJQcfSUebysJdzX4BgnZbIuMdgHkefXCF0Uh6tcmPo_YunnZJbaNMmeFRxYVdCVxyyeVgHpprX/s1600/04.bmp" /></a>(6.43)</div>
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where,</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8pFhvmWDFwn3EGJboAV7tU9EMWhGfXSibIyO4-zDfRhc6DYeNu9NRu9hytwTLSQ1Ad7rPxexDMDoL4e_4uW8zJGbGJ-YtCCwjUbPQYPy0qWbtRSuD7oh8TpUxlfU8Tt5M9FWQL-Me5dyF/s1600/04A.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="525" data-original-width="1051" height="318" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8pFhvmWDFwn3EGJboAV7tU9EMWhGfXSibIyO4-zDfRhc6DYeNu9NRu9hytwTLSQ1Ad7rPxexDMDoL4e_4uW8zJGbGJ-YtCCwjUbPQYPy0qWbtRSuD7oh8TpUxlfU8Tt5M9FWQL-Me5dyF/s640/04A.bmp" width="640" /></a></div>
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<br /><br />Equation (6.43) shows that the difference of pressures is constant and is not a function of a flowrate. Therefore, this type of device sometimes is called <u><i>the flowmeter with constant differential pressure</i></u>.<br /><br />An equation for the evaluation of the volumetric flowrate (m3/s) has final form as follows:</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZiks_3jwqdb-WLSVUcd8eQtpewhPYQ4QVu-Bo2RFMZQ_apBpDDccqKBqafzOu16R5Y5PFwQf2GRzhBQo0vWYwmtWlo4JzBNEjlTlZALOgkS7Peb8WvLl-sFqTl0sk9zmLcQYyKfb6Tmin/s1600/06.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="74" data-original-width="272" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZiks_3jwqdb-WLSVUcd8eQtpewhPYQ4QVu-Bo2RFMZQ_apBpDDccqKBqafzOu16R5Y5PFwQf2GRzhBQo0vWYwmtWlo4JzBNEjlTlZALOgkS7Peb8WvLl-sFqTl0sk9zmLcQYyKfb6Tmin/s1600/06.bmp" /></a>(6.44)</div>
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where,</div>
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<b><span lang="EN-AU" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-AU; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">φ -</span></b>- discharge coefficient taking into account friction of the fluid with the rotor and the tube, pressure losses due to vortex of fluid under and above the rotor, and changes of the stream form when it passes through the restriction area between the rotor and the tube;</div>
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<span lang="EN-AU" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-AU; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;"><b>S<i><sub>gap </sub></i></b></span>--the area of an annular gap (restriction) between the rotor and the wall of the tube, m2.</div>
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<b style="font-family: "Times New Roman", serif; font-size: 16px;">S<i><sub>gap </sub></i></b>is defined by the geometry of the float and pipe as follows:</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnsQerdA8qkxk2CvMna1_zThf5n9ozgBk3O2hy2hyayy0nCNcmK2gkL75vGCtTFp2orQDwvY1amkVGYEapuksUZXgxnllIrxqNztRG04x7LVJkGFhCdFd1DL3W6LqFcAipzq_c-igXis8P/s1600/07.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="51" data-original-width="270" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnsQerdA8qkxk2CvMna1_zThf5n9ozgBk3O2hy2hyayy0nCNcmK2gkL75vGCtTFp2orQDwvY1amkVGYEapuksUZXgxnllIrxqNztRG04x7LVJkGFhCdFd1DL3W6LqFcAipzq_c-igXis8P/s1600/07.bmp" /></a>(6.45)</div>
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where,</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMUC71I2TjO_shov1bGdtImhKDbA9SWgRI0h3m-sZ-GxDIze_5noYMNhYKI7MZJ81W3iSRa6LNA_K9uID_FUKBSnuKak6DaRwleZ3UjUTX7dvbdFGS55VBpSRCs1UC5ur28gCp0aBlz9bI/s1600/07A.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="233" data-original-width="1101" height="131" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMUC71I2TjO_shov1bGdtImhKDbA9SWgRI0h3m-sZ-GxDIze_5noYMNhYKI7MZJ81W3iSRa6LNA_K9uID_FUKBSnuKak6DaRwleZ3UjUTX7dvbdFGS55VBpSRCs1UC5ur28gCp0aBlz9bI/s640/07A.bmp" width="640" /></a></div>
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The accuracy of rotameters varies from<span lang="EN-AU" style="font-family: Symbol; font-size: 12.0pt; mso-ascii-font-family: "Times New Roman"; mso-bidi-font-size: 10.0pt; mso-char-type: symbol; mso-hansi-font-family: "Times New Roman"; mso-symbol-font-family: Symbol;">±</span><span lang="EN-AU" style="font-size: 12.0pt; mso-bidi-font-size: 10.0pt;">0.25 to </span><span lang="EN-AU" style="font-family: Symbol; font-size: 12.0pt; mso-ascii-font-family: "Times New Roman"; mso-bidi-font-size: 10.0pt; mso-char-type: symbol; mso-hansi-font-family: "Times New Roman"; mso-symbol-font-family: Symbol;">±</span><span lang="EN-AU"><span style="font-size: 12pt;">2%</span> (for individual calibration). Their repeatability is excellent. They can measure flowrates from 0.5<span style="font-size: 12pt;"> cm</span><sup style="font-size: 12pt;">3</sup><span style="font-size: 12pt;">/m<o:p></o:p></span></span>in to 1135 l/min of water.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikrmqJnmwVMUVyqANcEdxQUwkeEXk4lQt7nv0A9oMKlbUYr2j6JLGWHZuoX6DHJ5uChBRjCe2z-wklrsoggl2i06uijkgtmgx9KZSpsnwMkYiRh7ogMDPTJK6ZhW-bdT6BbXNghOtbFD66/s1600/Flange-Air-Water-Plastic-Liquid-Flow-Meter-Tube-Rotameter.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="800" data-original-width="760" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikrmqJnmwVMUVyqANcEdxQUwkeEXk4lQt7nv0A9oMKlbUYr2j6JLGWHZuoX6DHJ5uChBRjCe2z-wklrsoggl2i06uijkgtmgx9KZSpsnwMkYiRh7ogMDPTJK6ZhW-bdT6BbXNghOtbFD66/s320/Flange-Air-Water-Plastic-Liquid-Flow-Meter-Tube-Rotameter.jpg" width="304" /></a></div>
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<span lang="EN-AU" style="font-size: 12.0pt; mso-bidi-font-size: 10.0pt;"><o:p></o:p></span></div>
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<br /><i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i><br /><br /></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-28782523495118800012019-02-12T19:00:00.001+05:302019-02-12T19:00:57.063+05:30Orifice plates<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjerXfk3laWe_bU8Ji0LHGWE6KYtyWXFCuPlp_P0RWo_-kVjQRxXj1mJ3w8Zjq_TFislIW8_oq8_DZ0U6nCm3HEh6AFjSXtON00BQ4_fgooV4yRxlQo6xpQaWmGoRu_woyO8Jdw7fXL-Kuc/s1600/rosemount-1495-orifice-plate-2-paddle-family.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1024" data-original-width="1024" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjerXfk3laWe_bU8Ji0LHGWE6KYtyWXFCuPlp_P0RWo_-kVjQRxXj1mJ3w8Zjq_TFislIW8_oq8_DZ0U6nCm3HEh6AFjSXtON00BQ4_fgooV4yRxlQo6xpQaWmGoRu_woyO8Jdw7fXL-Kuc/s200/rosemount-1495-orifice-plate-2-paddle-family.jpg" width="200" /></a></div>
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This method is based in the phenomenon that a stream of fluid (liquid, gas or vapour) when passing through the restriction or primary device (orifice plate, Venturi plate, flow nozzle, etc.) is subjected to the change of kinetic and potential energy of the stream during variations of flowrate. Figure 6.1 shows an orifice plate. <div>
<br />Let’s consider two cases with incompressible and compressible fluids. <br /><br /><h4 style="text-align: left;">
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<u>Case 1. Incompressible fluid.</u></h4>
The following <b>assumptions</b> should be considered when derive working equations: <br /><br /><div class="separator" style="clear: both; text-align: center;">
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1 - fluid is incompressible, and there are no phase changes when fluid passes through the orifice; <br /><br />2 - fluid flow is steady and frictionless, ie. there are no energy losses due to friction; <br /><br />3 - flow is isothermal, ie. no heat losses or gains due to heat transfer between the fluid and its surroundings; <br /><br />4 - there is no in and outflow of energy between sections <u>A - A</u> and <u>B - B</u>; <br /><br />5 - mass flowrates in each cross-section of the stream is constant; <br /><br />6 - pipe is horizontal.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6YcBj95YZyaQsp0xnweMU8wnKdjT-W3nhQYkwEobLmq21leoIwoAfjhfHx6YD5pHehWul8FWvQP6KQuJt2QIdL0ase9JGflzNGqGDugLzoSO_6uW8js6CsmyNvdJr9zsU7KmfRL5iSvnf/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="564" data-original-width="597" height="377" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6YcBj95YZyaQsp0xnweMU8wnKdjT-W3nhQYkwEobLmq21leoIwoAfjhfHx6YD5pHehWul8FWvQP6KQuJt2QIdL0ase9JGflzNGqGDugLzoSO_6uW8js6CsmyNvdJr9zsU7KmfRL5iSvnf/s400/01.bmp" width="400" /></a></div>
Figure 6.1. Orifice plate. <b>(from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 286): </b><br /><br />An equation for conservation of mass flowrate is as follows:<div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOspb8NSY3HZ-WNu63wAWeN7df9c6JmRvU5rkkqF_EQeEqAbkbgNuDrK9UczUfBzHPMMTHwkoJCp7MM6y8h3N39lmRiPOVv8AZF0yyu-HGT_91_mUjzp5ajeTZdL9MHlzG-bV0o9quJ90N/s1600/02.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="36" data-original-width="255" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOspb8NSY3HZ-WNu63wAWeN7df9c6JmRvU5rkkqF_EQeEqAbkbgNuDrK9UczUfBzHPMMTHwkoJCp7MM6y8h3N39lmRiPOVv8AZF0yyu-HGT_91_mUjzp5ajeTZdL9MHlzG-bV0o9quJ90N/s1600/02.bmp" /></a> (6.1)</div>
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Since </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUJNDqdypBpYILCUiN_Cf4-yoACH7s9Pd9w2_jInrM18HYuurxZJUnfSa9GrnI9d1vJxsdsyKNacClS6a-IMhofC7NP8rq0bJXgE6D4tSY3BoGunRQhUAp6D9K5fmknDL_nADagGnm6jiO/s1600/03.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="38" data-original-width="110" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUJNDqdypBpYILCUiN_Cf4-yoACH7s9Pd9w2_jInrM18HYuurxZJUnfSa9GrnI9d1vJxsdsyKNacClS6a-IMhofC7NP8rq0bJXgE6D4tSY3BoGunRQhUAp6D9K5fmknDL_nADagGnm6jiO/s1600/03.bmp" /></a> (6.2)</div>
<br />then, we can give an equation for conservation of volumetric flowrate<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcDq6m1IoI3hTx3UviWDg9Y7hmylenQFFR3VcVe6HL-cLkILRuW8wG0qphDhErYwN43H_yhRRE0ji-iJ1vTDe-B4DF8yDgAC3PRUBt1j_6RSlc7o89iGnUm9fC0YiAughspiWtPNvbE5bP/s1600/04.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="38" data-original-width="140" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcDq6m1IoI3hTx3UviWDg9Y7hmylenQFFR3VcVe6HL-cLkILRuW8wG0qphDhErYwN43H_yhRRE0ji-iJ1vTDe-B4DF8yDgAC3PRUBt1j_6RSlc7o89iGnUm9fC0YiAughspiWtPNvbE5bP/s1600/04.bmp" /></a> (6.3)</div>
<br />When a volumetric flow rate in a pipe (see Figure 6.2) increases, then the velocity of the fluid through the orifice should increase as well. Since <span lang="EN-AU" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-AU; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">S<sub>A</sub>>S<sub>B</sub> </span>, then <span lang="EN-AU" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-AU; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">v<sub>A</sub><v<sub>B</sub></span>. Due to inertia the smallest cross-section area of the stream is not in the plane of the orifice itself, but some distance downstream from it. The total energy of the stream is equal to the sum of its kinetic energy and static head of the stream.<br /><br /><div style="text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-h2SEb_nW_aBRY3nj-N48UWAFoI3-Xx5FH73Vuqe_s1yKRWcC9fcjPq7N95vuInBq-9GDwPUNK4a8nhf3vFm9Vuvp0tnyf4OCJ1sw8WtaGbtWb-5pxxZ00Oeg3DrYWVjmt1VSFGoJGpTd/s1600/05.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="594" data-original-width="625" height="304" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-h2SEb_nW_aBRY3nj-N48UWAFoI3-Xx5FH73Vuqe_s1yKRWcC9fcjPq7N95vuInBq-9GDwPUNK4a8nhf3vFm9Vuvp0tnyf4OCJ1sw8WtaGbtWb-5pxxZ00Oeg3DrYWVjmt1VSFGoJGpTd/s320/05.bmp" width="320" /></a></div>
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Figure 6.2. Orifice-type differential pressure flowmeter.</div>
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Since the kinetic energy increases (due to the increasing of the velocity of the stream in cross-section <u>B - B</u>), then the static head should decrease. This static head is responsible for the static pressure of the stream. Therefore, there is a head difference in two cross-sections (<span style="font-family: "Times New Roman", serif; font-size: 12pt;">ΔP=P</span><sub style="font-family: "Times New Roman", serif;">A</sub><span style="font-family: "Times New Roman", serif; font-size: 12pt;">-P</span><sub style="font-family: "Times New Roman", serif;">B</sub>), namely the differential pressure, which is the function of the velocity and finally of the flowrate of the stream. It means that for each value of the flowrate corresponds a certain value of a differential pressure. Therefore, we can measure this differential pressure and, finally, evaluate the required value of the flowrate. </div>
<br />Equations for potential and kinetic energies of the fluid stream and work performed by it are as follows <b>(from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 280</b>):<br /><div>
<br /></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSg3N7NSaUd_mL_1YD3dM76AOlx3dzdkXhHx-jpJbpjF1HKAVZdPGzai80E9RbhAKBuSZmAwcsscI-qGqpN0lV-JRI1uFnRaZbAM2etA52M_T3PRq9RvfzM1dsvAJFs6ikqjy-wEYLIXvy/s1600/06.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="239" data-original-width="795" height="96" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSg3N7NSaUd_mL_1YD3dM76AOlx3dzdkXhHx-jpJbpjF1HKAVZdPGzai80E9RbhAKBuSZmAwcsscI-qGqpN0lV-JRI1uFnRaZbAM2etA52M_T3PRq9RvfzM1dsvAJFs6ikqjy-wEYLIXvy/s320/06.bmp" width="320" /></a></div>
<br /><br />Combine equations <b>(6.4) - (6.5)</b> and get an equation for the conservation of the total energy per unit mass of the stream for the case of two cross-sections <u>A - A</u> and <u>B - B</u>:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiScV34GhhwIxGc0J3pYk1LekrbfJSCpCo6yN79_gm3hJ_KHrlV8JnWRJedx2pRnOCvvsfMcQ0CT3s8JyWGVrwUwpKl1Co2vkzTtqQwd2y9pIFrX6Q32DYlJzty7jdqpw29VCEjPGgSzktH/s1600/07.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="67" data-original-width="247" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiScV34GhhwIxGc0J3pYk1LekrbfJSCpCo6yN79_gm3hJ_KHrlV8JnWRJedx2pRnOCvvsfMcQ0CT3s8JyWGVrwUwpKl1Co2vkzTtqQwd2y9pIFrX6Q32DYlJzty7jdqpw29VCEjPGgSzktH/s1600/07.bmp" /></a>(6.7)</div>
or, since the pipe is horizontal (the assumption 6)<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
then <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8WQAdDqylTh_ZXnQ7X7X6xmuUB-fcLVhzUMmFjNzIsxfDjU0EsRyFpmnxgQIihuMb0MWXGYsLhDRau9EqUUvygJJ29bMHF1ifP6yp22cHOje32uPnH5BEmNj5vA5fBfAQwR5mbl6yufbR/s1600/08.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="208" data-original-width="769" height="86" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8WQAdDqylTh_ZXnQ7X7X6xmuUB-fcLVhzUMmFjNzIsxfDjU0EsRyFpmnxgQIihuMb0MWXGYsLhDRau9EqUUvygJJ29bMHF1ifP6yp22cHOje32uPnH5BEmNj5vA5fBfAQwR5mbl6yufbR/s320/08.bmp" width="320" /></a></div>
<br />From equation (6.9) we can get an expression for the velocity of the stream in the cross-section <u>B - B</u>:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGIS4IK3OTq2mNigSV48YnaH1AKp41VHLWtCT8JgMYYSea3gFKHRO2JOOYCDI4eDUo_WgN51Tpus-wUYcnLxWEYGGYlSsMYW7sEN_GXLOM5QZgx0RW58xgX0SkQYsuTHM8ZKUbuF5XGuFy/s1600/09.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="342" data-original-width="952" height="114" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGIS4IK3OTq2mNigSV48YnaH1AKp41VHLWtCT8JgMYYSea3gFKHRO2JOOYCDI4eDUo_WgN51Tpus-wUYcnLxWEYGGYlSsMYW7sEN_GXLOM5QZgx0RW58xgX0SkQYsuTHM8ZKUbuF5XGuFy/s320/09.bmp" width="320" /></a></div>
A theoretical equation for the flow of a fluid is as follows:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_vtLFpzT6Gh8vHbPrmesCTRhZEtTMx5pHZFQ56BFmaeG9mJD8ert6DI0YpEkaKCUUUZk6HajxwCWEZeenvtrUK2C3E0kiMOgu-1_Q182bp2Zxxyfw7bvKHq5YvVvltlzDfnGbSq3oN5Ad/s1600/10.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="100" data-original-width="303" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_vtLFpzT6Gh8vHbPrmesCTRhZEtTMx5pHZFQ56BFmaeG9mJD8ert6DI0YpEkaKCUUUZk6HajxwCWEZeenvtrUK2C3E0kiMOgu-1_Q182bp2Zxxyfw7bvKHq5YvVvltlzDfnGbSq3oN5Ad/s1600/10.bmp" /></a>(6.12)</div>
<div>
<br /></div>
Frictionless flow is only approached at well-established turbulent flows. We are not able to measure <span style="font-family: "Times New Roman", serif; font-size: 16px;">S</span><sub style="font-family: "Times New Roman", serif;">A</sub>and <span style="font-family: "Times New Roman", serif; font-size: 16px;">S</span><sub style="font-family: "Times New Roman", serif;">B</sub>, which vary with the variation of fluid flowrate. So, we need to modify equation (6.12) and get a practical equation for the evaluation of fluid volumetric flowrate:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsuQUWy9MNHD5ows2Ylsi5RT1RkOCRkHWK0VQGUAr9wFl1HA1xpSWQTM3aLwOtsxC6_piJbnu4KIjgZX0Vd3I_t-GOEBG0G89ClqbLaTfQ9KWOP9Y8eDOur1S2HZpvFS-_ax69qxuSsh54/s1600/11.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="57" data-original-width="225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsuQUWy9MNHD5ows2Ylsi5RT1RkOCRkHWK0VQGUAr9wFl1HA1xpSWQTM3aLwOtsxC6_piJbnu4KIjgZX0Vd3I_t-GOEBG0G89ClqbLaTfQ9KWOP9Y8eDOur1S2HZpvFS-_ax69qxuSsh54/s1600/11.bmp" /></a>(6.13)</div>
In the above equations we used the following parameters:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8kG5AfWeWRbQ8qu28RVstHogo6D4o3MqHu5RXRw2zSa0lC9E-7UBQLQg3ARQJLywinda0JiOn6amFPr7QkoOlrBN5R4I9h28BYVYNwwYB41KOAqjRWfUukvGB88GxPzKHeMn8W5xJ15nS/s1600/12.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="660" data-original-width="1015" height="416" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8kG5AfWeWRbQ8qu28RVstHogo6D4o3MqHu5RXRw2zSa0lC9E-7UBQLQg3ARQJLywinda0JiOn6amFPr7QkoOlrBN5R4I9h28BYVYNwwYB41KOAqjRWfUukvGB88GxPzKHeMn8W5xJ15nS/s640/12.bmp" width="640" /></a></div>
<br /><br /><h4 style="text-align: left;">
Case 2. Compressible fluid.</h4>
<div>
<br />In this case the density of a fluid depends on pressure in the form <b>(from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 287)</b>:</div>
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVaVyWcmc6e28_6F11jKZAywSnJtCGSTzeAwW22drz6IWDo1k-31xcaj9-qUL2ACKSWWUkS-Dw9wto7E_2v4P-E4F_ma0WnZCVqOSAfjIdd2Gu1bF-ZsUh4JrNB9SCEf9ElsBzIg2MhKp_/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="249" data-original-width="1000" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVaVyWcmc6e28_6F11jKZAywSnJtCGSTzeAwW22drz6IWDo1k-31xcaj9-qUL2ACKSWWUkS-Dw9wto7E_2v4P-E4F_ma0WnZCVqOSAfjIdd2Gu1bF-ZsUh4JrNB9SCEf9ElsBzIg2MhKp_/s640/01.bmp" width="640" /></a></div>
From (6.14) we have:<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbhETQO3Sp6z2pqOysl65hup5mAIb1bZLcwPCv33Y7bFa2h1z0i9_JhZgsa4E_i-QS-1qVCfC8BoOhsmdfnto_xgOKBfOzZL2DMy28sv0_7qAS_LC3nolDQeSXKbD7AlTxWEZX_6KTj4Qc/s1600/02.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="189" data-original-width="684" height="110" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbhETQO3Sp6z2pqOysl65hup5mAIb1bZLcwPCv33Y7bFa2h1z0i9_JhZgsa4E_i-QS-1qVCfC8BoOhsmdfnto_xgOKBfOzZL2DMy28sv0_7qAS_LC3nolDQeSXKbD7AlTxWEZX_6KTj4Qc/s400/02.bmp" width="400" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_oFeHNHpzypATbMOEBlLQtb-9mVkra1VXF4P2ZHOA-zEW8jLbaOsAcJN6_3r3A51tVx4YUoERm2DrGfa3M6G8Um6taQik1-uNX9t72OuKZL1eWPI_7DbJ3p17T4BNKoXypersi71vnkkT/s1600/03.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="153" data-original-width="368" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_oFeHNHpzypATbMOEBlLQtb-9mVkra1VXF4P2ZHOA-zEW8jLbaOsAcJN6_3r3A51tVx4YUoERm2DrGfa3M6G8Um6taQik1-uNX9t72OuKZL1eWPI_7DbJ3p17T4BNKoXypersi71vnkkT/s320/03.bmp" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: left;">
Let’s integrate an expression </div>
<div class="separator" style="clear: both; text-align: left;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLKS56d3ITliSFo1FhlszM5hNSM7CqttPLtjuyb1w2w_ZHO-zRVF5Zy6ZKLam_Uy9fFDV4k5djJdUFrcfkG8YQ9vC_Vah5UXBv2WFnl0jBpL4Z3gOE62U5SEtlENHhQTJia4ljFdvoOq7G/s1600/04.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="124" data-original-width="56" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLKS56d3ITliSFo1FhlszM5hNSM7CqttPLtjuyb1w2w_ZHO-zRVF5Zy6ZKLam_Uy9fFDV4k5djJdUFrcfkG8YQ9vC_Vah5UXBv2WFnl0jBpL4Z3gOE62U5SEtlENHhQTJia4ljFdvoOq7G/s1600/04.bmp" /></a> Then: </div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4_vKMp70_a7UG2X7O7XlHTtZBWprm8Ll49Mt1KLs9t7S8DL3t0ao4mWX1md-9YmpDzvwDWr11-HGMrMIDEz3hNesY4FLvwX_IJaDrJDM9QawWgGavdHpfvRuy8jMxGW5iTM955zSL2uSo/s1600/05.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="681" data-original-width="1071" height="404" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4_vKMp70_a7UG2X7O7XlHTtZBWprm8Ll49Mt1KLs9t7S8DL3t0ao4mWX1md-9YmpDzvwDWr11-HGMrMIDEz3hNesY4FLvwX_IJaDrJDM9QawWgGavdHpfvRuy8jMxGW5iTM955zSL2uSo/s640/05.bmp" width="640" /></a></div>
Now we can re-write Bernoulli equation in the following form:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0vROCZP5vsb_cbYxwSSaVIqM4au6r8li2Sirqa7NQHdbXhPonm8J_iZScn9b-25KD7qgAYrMiyeMmlgKL3ZRyDPeiwIj9nSv6FjmWXXnCWLjNAGJvh4Sur-mpGGN-Q_eLwXaXkCLPTrY7/s1600/06.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="74" data-original-width="328" height="90" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0vROCZP5vsb_cbYxwSSaVIqM4au6r8li2Sirqa7NQHdbXhPonm8J_iZScn9b-25KD7qgAYrMiyeMmlgKL3ZRyDPeiwIj9nSv6FjmWXXnCWLjNAGJvh4Sur-mpGGN-Q_eLwXaXkCLPTrY7/s400/06.bmp" width="400" /></a>(6.16)</div>
or, since <span lang="EN-AU" style="font-family: "Times New Roman","serif"; font-size: 12.0pt; mso-ansi-language: EN-AU; mso-bidi-font-size: 10.0pt; mso-bidi-language: AR-SA; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-US;">z<sub>A</sub>=z<sub>B</sub></span> then,<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcNTQulAuUbuD2c_Bix-2_zqrrK6gz6U0tN1OHI3eNt45sgp8YTZnjigiiKfG9j5N6dgFj1OUDRmmMNYfnRe0VCZ-9TBI-jA5mC06GPv4Qo2M98oas1jCU0lCZg2lSZx9AC8hIOKowMAy3/s1600/07.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="64" data-original-width="242" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcNTQulAuUbuD2c_Bix-2_zqrrK6gz6U0tN1OHI3eNt45sgp8YTZnjigiiKfG9j5N6dgFj1OUDRmmMNYfnRe0VCZ-9TBI-jA5mC06GPv4Qo2M98oas1jCU0lCZg2lSZx9AC8hIOKowMAy3/s1600/07.bmp" /></a>(6.17)</div>
During the flow of a compressible fluid we have:<div>
<br /></div>
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguDmkNGJ0ZqBfieedI99Zsv_mqbSkhbS8lIGZP5vdQLRt6SzBjpr6KFhgwdJW03nAgBcUVuRNPTvhDBwtwyMUhyHFzSh9ZoAFgxcP_9WGsveDta8cvsNwOigpDHk-c7hbrmdwe43kZyGUR/s1600/08.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="35" data-original-width="80" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguDmkNGJ0ZqBfieedI99Zsv_mqbSkhbS8lIGZP5vdQLRt6SzBjpr6KFhgwdJW03nAgBcUVuRNPTvhDBwtwyMUhyHFzSh9ZoAFgxcP_9WGsveDta8cvsNwOigpDHk-c7hbrmdwe43kZyGUR/s1600/08.bmp" /></a><span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">(6.18)</span></div>
<div>
<span style="font-family: Times New Roman, serif;"><span style="font-size: 13.3333px;">and therefore, </span></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM4SvkF3JSnxhd9HeRbIW4gupGAr7GBiE2aoOoXDdInnaXTwWGmZf3V1INvfZsQKDqkDNuPEBFve1nbUDNrICoG92NI-VMYepHX-2DW-wdViFrXT8DozfXuutPpX8_GkWkkiKTwejkXEbK/s1600/09.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="35" data-original-width="80" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM4SvkF3JSnxhd9HeRbIW4gupGAr7GBiE2aoOoXDdInnaXTwWGmZf3V1INvfZsQKDqkDNuPEBFve1nbUDNrICoG92NI-VMYepHX-2DW-wdViFrXT8DozfXuutPpX8_GkWkkiKTwejkXEbK/s1600/09.bmp" /></a><span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">(6.19)</span></div>
<div>
<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;"><br /></span></div>
<div>
<span style="font-family: Times New Roman, serif;"><span style="font-size: 13.3333px;">So, </span></span><div class="separator" style="clear: both; font-family: "Times New Roman", serif; font-size: 13.3333px; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRNvrcpsCmS0XTeFUFEOwBlVgBR6-HBu7wf9c3_cO_6EaT86P-9e1jUUepO3TSeTbILfoW03J-_H4rKN6JJuKki2NYQtOArcJ0enGmJKT49_AX6k90Bt0nnzFymPOOAsuvxKClF59C7b3W/s1600/10.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="35" data-original-width="81" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRNvrcpsCmS0XTeFUFEOwBlVgBR6-HBu7wf9c3_cO_6EaT86P-9e1jUUepO3TSeTbILfoW03J-_H4rKN6JJuKki2NYQtOArcJ0enGmJKT49_AX6k90Bt0nnzFymPOOAsuvxKClF59C7b3W/s1600/10.bmp" /></a>(6.20)</div>
<div class="separator" style="clear: both; font-family: "Times New Roman", serif; font-size: 13.3333px; text-align: left;">
and </div>
<div class="separator" style="clear: both; font-family: "Times New Roman", serif; font-size: 13.3333px; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHfNLjNBJbTvdhTzxCYwoZUhJ1nsukerZz_5KBy7DADbDKdzv2RICH1cpYTrvSqSM3riXoX7_Cd0bFqshyphenhyphenySACVjcXeIAzLZqaQ3i8t_1IbIq6hsMoF8STXzFEnJmmZxioJxNDJzt6MRet/s1600/11.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="35" data-original-width="83" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHfNLjNBJbTvdhTzxCYwoZUhJ1nsukerZz_5KBy7DADbDKdzv2RICH1cpYTrvSqSM3riXoX7_Cd0bFqshyphenhyphenySACVjcXeIAzLZqaQ3i8t_1IbIq6hsMoF8STXzFEnJmmZxioJxNDJzt6MRet/s1600/11.bmp" /></a>(6.21)</div>
<br />Therefore, mass flowrate is used in gas metering. A theoretical equation for a compressible flow has the following form:</div>
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjijy92Mo9h9T0SVxYkJt8hD7_MLMmFmLuLvY3aq8FGKqeK1G6-spDjuZmPCqfcwNQPdYncjQUIXmvY3No44tmuFM9jGRX4qMQOQ5TBQh3Mi3w1NdNKEADGSFT3fAUFvEiPMbK2u45kIQNI/s1600/12.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="86" data-original-width="289" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjijy92Mo9h9T0SVxYkJt8hD7_MLMmFmLuLvY3aq8FGKqeK1G6-spDjuZmPCqfcwNQPdYncjQUIXmvY3No44tmuFM9jGRX4qMQOQ5TBQh3Mi3w1NdNKEADGSFT3fAUFvEiPMbK2u45kIQNI/s1600/12.bmp" /></a>(6.22)</div>
<br />A practical equation for a compressible flow has the following form:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfb6d-YnwAm0jTbo4-HD5LhNVHkwPOfFfwB-Pq5DdxcJ3X7p0L9tary7QYf6I2FrV4J6LKhyjg3YhxMEG8pzykIcykpV0_sV-rqHxfmaFM5lIojV2ySbF1UZUjBGz3dkE5INufP_1Y5vxt/s1600/13.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="35" data-original-width="254" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfb6d-YnwAm0jTbo4-HD5LhNVHkwPOfFfwB-Pq5DdxcJ3X7p0L9tary7QYf6I2FrV4J6LKhyjg3YhxMEG8pzykIcykpV0_sV-rqHxfmaFM5lIojV2ySbF1UZUjBGz3dkE5INufP_1Y5vxt/s1600/13.bmp" /></a>(6.23)</div>
<br />where, the expansibility factor has the following form according to <b>BS 1041</b> and<b> ISO 5167 (from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 288)</b>:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiMclIie3aZz1jAF5OgwfNjM2St3vKJ5AlmgeT6mTYgfjotGKUL_C9ibsROJv_yAj37mPo3TkGPRB_CLvHCU-fprpIo0UJum6ZZxG7ZOF5EGLgfD-Q2mASPQQZGQ14OUns-HDNqtWEpIUI_/s1600/14.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="50" data-original-width="268" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiMclIie3aZz1jAF5OgwfNjM2St3vKJ5AlmgeT6mTYgfjotGKUL_C9ibsROJv_yAj37mPo3TkGPRB_CLvHCU-fprpIo0UJum6ZZxG7ZOF5EGLgfD-Q2mASPQQZGQ14OUns-HDNqtWEpIUI_/s1600/14.bmp" /></a>(6.24)</div>
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For liquids <span style="font-family: "Times New Roman", serif; font-size: 12pt;"> </span><span style="font-family: "Times New Roman", serif; font-size: 12pt;">ꜫ
=1.0</span><span style="font-family: "Times New Roman", serif; font-size: 12pt;"> </span></div>
<div>
<br /></div>
Below are given equations and data, which should be used during calculations of flowrates when orifice plates are used.<br /><br /><h4 style="text-align: center;">
<u>Discharge coefficient data for orifice plate, BS 1042.</u></h4>
The Stolz equation:<br /><div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy2GDp0Fp8XLCIUUeCQPn8PUQlNqXlx4FUKglG_XCJYskrb8oBIPbSw2GPHAhq1kiqLbv3P5VKcV3PuKTaeVdtBb4RjXANFp9cEa_EL_fBomTC_FbEy5iK-j5I6aYsUg0qZuhZMWxjWCmk/s1600/01.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="120" data-original-width="405" height="117" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy2GDp0Fp8XLCIUUeCQPn8PUQlNqXlx4FUKglG_XCJYskrb8oBIPbSw2GPHAhq1kiqLbv3P5VKcV3PuKTaeVdtBb4RjXANFp9cEa_EL_fBomTC_FbEy5iK-j5I6aYsUg0qZuhZMWxjWCmk/s400/01.bmp" width="400" /></a>(6.25)</div>
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If</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgk_uHbY1YRFehHcKFzZxvDa5eLVbe7PLNIPlR_4CzK_3THVTTloScF5siuqN6CRrfLTamtLr50YeRjFvwQGCLcXU3X-RN7PT6uEHJwV-ciZg70o7M-UoVKUTBf1M5rIDLw0fYICRFYbRAf/s1600/02.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="64" data-original-width="169" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgk_uHbY1YRFehHcKFzZxvDa5eLVbe7PLNIPlR_4CzK_3THVTTloScF5siuqN6CRrfLTamtLr50YeRjFvwQGCLcXU3X-RN7PT6uEHJwV-ciZg70o7M-UoVKUTBf1M5rIDLw0fYICRFYbRAf/s1600/02.bmp" /></a>(6.26)</div>
<div class="separator" style="clear: both; text-align: left;">
then, </div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimeBRHYFxLi-_-iz6Cr1eRb7BLJp5tor1QdLCSql0ydBRTkcqk6wtMogdBwj3E6QfYVLaPhR_QO-V-PeQukjeZGwIgm1Au3ve3lqmNelU_1nDieNp9QoJdc5W8fVeUDvj28QipXmWdq2gB/s1600/03.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="63" data-original-width="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimeBRHYFxLi-_-iz6Cr1eRb7BLJp5tor1QdLCSql0ydBRTkcqk6wtMogdBwj3E6QfYVLaPhR_QO-V-PeQukjeZGwIgm1Au3ve3lqmNelU_1nDieNp9QoJdc5W8fVeUDvj28QipXmWdq2gB/s1600/03.bmp" /></a>(6.27)</div>
For corner tappings:<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8qpsQuwX-Nn4Mm1rY3ZDDlW7g03C4gOlMCMV4GYa5AmtL32c6Q9bw-GluW5WRgqJZ6uqhqRkUsRlfkH6ucGWZTIuQczi8t5JXXjDYNXlCf0xsYYfraer6y_8UUYUDVZs9U1W459r5bGuF/s1600/04.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="38" data-original-width="106" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8qpsQuwX-Nn4Mm1rY3ZDDlW7g03C4gOlMCMV4GYa5AmtL32c6Q9bw-GluW5WRgqJZ6uqhqRkUsRlfkH6ucGWZTIuQczi8t5JXXjDYNXlCf0xsYYfraer6y_8UUYUDVZs9U1W459r5bGuF/s1600/04.bmp" /></a>(6.28)</div>
For flange tappings: <br /><div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCaO6s2DNP5VrOzoQEMEsJyfRA9skqfWH2VKbdMkl4Y56reC0sT11GYEl-Faj1XWT9MSe4p713PtW4owuGg9z0BjcXGxoqdWTnP8H1Um07GlSeZdj977AOO_UZ-TmDmFi-Pc6shiDbl0mG/s1600/05.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="52" data-original-width="114" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCaO6s2DNP5VrOzoQEMEsJyfRA9skqfWH2VKbdMkl4Y56reC0sT11GYEl-Faj1XWT9MSe4p713PtW4owuGg9z0BjcXGxoqdWTnP8H1Um07GlSeZdj977AOO_UZ-TmDmFi-Pc6shiDbl0mG/s1600/05.bmp" /></a>(6.29)</div>
<br /><b><u><i>a). Conditions of validity for corner taps:</i></u></b><div>
<b><i><u><br /></u></i></b></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGAFm1P95mkajhlpk722VBZn0U3FvCpQ9ORe77i00HdhYOisWVaYMLHhRS7kvburSMKrXIlANBr5vSDxiEzBOIQkVu_k_TBRrPCQRHy-6y5KxWeuk64s7fIwEKlvQVVq3MQB5xwWW_9pUI/s1600/06.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="376" data-original-width="1032" height="232" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGAFm1P95mkajhlpk722VBZn0U3FvCpQ9ORe77i00HdhYOisWVaYMLHhRS7kvburSMKrXIlANBr5vSDxiEzBOIQkVu_k_TBRrPCQRHy-6y5KxWeuk64s7fIwEKlvQVVq3MQB5xwWW_9pUI/s640/06.bmp" width="640" /></a></div>
<b><u><i>b). Conditions of validity for flange taps:</i></u></b><div>
<b><i><u><br /></u></i></b><div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjViglMC8FDPEfrGXKc-NvbI558IMmVHYO3qGn7vXyJ9ORhxaaN1-nsPB4p6udlmc_ywtSki_MwYcveYDY-iTmROXcN0nS1YD7kAH5kqbjuHl00DI6H-idZEFqtaVI_XiX3JrfSBqcMpBJF/s1600/07.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="222" data-original-width="903" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjViglMC8FDPEfrGXKc-NvbI558IMmVHYO3qGn7vXyJ9ORhxaaN1-nsPB4p6udlmc_ywtSki_MwYcveYDY-iTmROXcN0nS1YD7kAH5kqbjuHl00DI6H-idZEFqtaVI_XiX3JrfSBqcMpBJF/s640/07.bmp" width="640" /></a></div>
<br />To calculate the value of D<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">or</span> one need to perform several iterations until this value is obtained with the accuracy equal to the tolerance <span style="font-family: "Times New Roman", serif; font-size: 12pt;">δ </span> of machining of the surface of an orifice.</div>
<div>
<div>
<b><u><i></i></u></b></div>
</div>
<br />Step 1. Calculate Re.<br />Step 2. Set initial guess for parameters as follows:<b> C=0.6, ꜫ =1.0 , E=1.0</b><br />Step 3. Calculate area <b>S</b><span style="font-family: "Times New Roman", serif; font-size: 13.3333px;"><b>or</b></span> of the orifice hole using (6.13) or (6.23) and value of maximum flowrate.<br />Step 4. Calculate <b>D</b><span style="font-family: "Times New Roman", serif; font-size: 13.3333px;"><b>or</b></span><b>.</b><br />Step 5. Calculate <b>β.</b><br />Step 6. Revise the value of <b>E</b> according to <div>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9w7xZmlZDgv9gedmYoT8VNqX-rRUSvHvhR_Qj4LLZArinXYSmB1vFH4K0iDNAQRs0V8K8lKZDod8NGLuzcHnRnayvDRB3rCmT2Bb3apWRhOEqmVmcti_xSQGnevijfSi7LBeay8LivRgh/s1600/08.bmp"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9w7xZmlZDgv9gedmYoT8VNqX-rRUSvHvhR_Qj4LLZArinXYSmB1vFH4K0iDNAQRs0V8K8lKZDod8NGLuzcHnRnayvDRB3rCmT2Bb3apWRhOEqmVmcti_xSQGnevijfSi7LBeay8LivRgh/s1600/08.bmp" /></a><br /><br />Step 7. If we have liquid, then <b>ꜫ =1.0</b>. Evaluate <b>C</b> according to (6.25). Then continue starting from step 3, and so on.<br />Step 8. If we have gas, then if <br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ4_2aB2liDWT1L8Gc4R7gtC9c9mxiFEGEdysrrB_3GfU4dAVdwqOgz-21XMn_lusfBacdNN3_GnaRKjzuN0RZezvCCYhyGzmXBDKAF5FInLso9d1eySp3GunjNOzrxWtBWAfrt8PYzLeC/s1600/09.bmp"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ4_2aB2liDWT1L8Gc4R7gtC9c9mxiFEGEdysrrB_3GfU4dAVdwqOgz-21XMn_lusfBacdNN3_GnaRKjzuN0RZezvCCYhyGzmXBDKAF5FInLso9d1eySp3GunjNOzrxWtBWAfrt8PYzLeC/s1600/09.bmp" /></a>evaluate <b>ꜫ </b> according to (6.24). Evaluate <b>C </b> according to (6.25). Then continue starting from step 3, and so on.<br />Step 9. Check if <b>D<span style="font-family: "Times New Roman", serif; font-size: 13.3333px;">or</span>. </b>>=12.5mm .<br />Step 10. Check if final values of <b>β </b>and <b>Re</b> are within limits.<br /></div>
</div>
<div>
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<div>
<i style="background-color: white; color: #4c4c4c; font-family: Arial, sans-serif; font-size: xx-small; margin: 0px; padding: 0px;"><span style="font-family: "trebuchet ms", sans-serif; margin: 0px; padding: 0px;"><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-69376784703450446652016-10-11T21:23:00.001+05:302019-02-19T15:44:43.549+05:30Instrumentation for flow measurements<div dir="ltr" style="text-align: left;" trbidi="on">
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Flowrate measurements are important in control of chemical processes. Having measured flowrates of gases, liquids or vapours it is possible to evaluate mass balance of the process. Flowrate is the quantity of a substance passed through the given cross-section area in the unit of time.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEj35BJaCH0t_Mc2tewf_TwyEutmt5R6o94xnYMiE_-7w5wyK8yxWlS5dLx3oOb4TJ8Jx8qUHphFEPDwycOkMmGHJo99zGeN22d5u06VUmOxFGHHlIbb0CBFB_mPT_2wQ3PZZuR4soPAHY/s1600/Electromagnetic+flow+meters+use+Faraday%25E2%2580%2599s+law+of+electromagnetic+induction+for+making+a+flow+measurement..gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEj35BJaCH0t_Mc2tewf_TwyEutmt5R6o94xnYMiE_-7w5wyK8yxWlS5dLx3oOb4TJ8Jx8qUHphFEPDwycOkMmGHJo99zGeN22d5u06VUmOxFGHHlIbb0CBFB_mPT_2wQ3PZZuR4soPAHY/s1600/Electromagnetic+flow+meters+use+Faraday%25E2%2580%2599s+law+of+electromagnetic+induction+for+making+a+flow+measurement..gif" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCf4DE9cXoggXVX9RagtTFIIwcKjtDC9NvB8oGP74KhdKxCjcY_rHK8CQKOp3f_HilDKZjpjgWkk2xO-D9Hl7sR_pW_SZCZWC2tWZCdDA8vCii7C7j_g5ta2ifdTNTrCfqHZLRq3D6C-VO/s1600/blog.gif" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="154" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCf4DE9cXoggXVX9RagtTFIIwcKjtDC9NvB8oGP74KhdKxCjcY_rHK8CQKOp3f_HilDKZjpjgWkk2xO-D9Hl7sR_pW_SZCZWC2tWZCdDA8vCii7C7j_g5ta2ifdTNTrCfqHZLRq3D6C-VO/s200/blog.gif" width="200" /></a>There are a volumetric flowrate and mass flowrate. The first is expressed in m3/s, m3/h, cm3/s, l/s etc., while the second - in kg/s, kg/h, g/s, etc. Usually the volumetric or mass flowrates are applied to liquids (since liquids are incompressible); the mass flowrate is applied to gases and vapours (they are compressible).<br />
<br />
Flowrate measurement is not an easy problem, since many factors such as density, viscosity, ratio of phases, temperature, pressure, etc. of the stream have influence on the results of flowrate measurements. If calibration of the device for flowrate measurement was carried out at conditions different from those when it is used in practice, then we will get inaccurate flowrate data.<br />
<br />
We'll discuss in the coming posts operational principles of several instruments, which employ some of widely known methods for flowrate measurements commonly used in industrial environment as below :<br />
<ul style="text-align: left;">
<li><a href="http://aboutinstrumentation.blogspot.com/2019/02/orifice-plates.html" target="_blank">Orifice plates</a></li>
<li><a href="http://aboutinstrumentation.blogspot.com/2019/02/rotameters.html" target="_blank">Rotameters</a></li>
<li><a href="http://aboutinstrumentation.blogspot.com/2019/02/venturi-flow-nozzle.html" target="_blank">Venturi flow nozzle</a></li>
<li><a href="http://aboutinstrumentation.blogspot.com/2019/02/turbine-flowmeters.html" target="_blank">Turbine flowmeters</a></li>
<li><a href="http://aboutinstrumentation.blogspot.com/2019/02/ultrasound-flowmeters.html" target="_blank">Ultrasound flowmeters</a></li>
</ul>
<div>
<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-84218651957009395642016-09-17T03:30:00.000+05:302016-09-17T03:37:54.533+05:30Nucleonic devices : Level<div dir="ltr" style="text-align: left;" trbidi="on">
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The phenomenon of reducing the intensity of gamma radiation when passing through liquids or solids is used in nucleonic devices for measurement of level of liquids and solids. Fig. 5.16 presents radiation-type level detector.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0xQelWDD9QNjgKS-i2GjxjRF6FPnMKJNCOihh3n1xpoh3HxCrfUmmADGiLUzYhENuMrPpwufDnfb175xg-DT86BiEkSHzZrFPDpTAGOiZrSB48hVkqf1MFVb75ue43dWe5OFr-gzBe7mU/s1600/03.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="227" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0xQelWDD9QNjgKS-i2GjxjRF6FPnMKJNCOihh3n1xpoh3HxCrfUmmADGiLUzYhENuMrPpwufDnfb175xg-DT86BiEkSHzZrFPDpTAGOiZrSB48hVkqf1MFVb75ue43dWe5OFr-gzBe7mU/s320/03.png" width="320" /></a></div>
<div style="text-align: center;">
<i>Figure 5.16. Nucleonic level system.</i></div>
<br />
A small quantity of radioactive substance (Cobalt 60, Radium 226, etc.) is placed in a source unit 1. This unit is attached to the wall of a tank 2 filled with a substance 3 which level is to be measured. A radiation detector 4, usually Geiger-Mueller tubes, is fixed to the wall of the tank on the opposite side of the tank. The intensity of gamma-radiation detected by the detector decreases with the increase of the level of a substance. The absorption of gamma-radiation by the wall of the tank is constant, whereas that of the gas space above the substance is negligible. A gamma-detector converts the gamma-radiation into the output signal (a series of small current pulses). This signal then is converted into a standard electrical signal, which can be measured by a secondary device or fed into a controller.<br />
<br />
An accuracy of these devices can achieve <i>+/- </i>1% of the span. The advantage of nucleonic level devices is that nothing comes in contact with the substance under measurement. Among disadvantages we can note the high cost and the difficulties with handling of radioactive materials.<br />
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<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-37876656073744017332016-09-17T03:26:00.002+05:302016-09-17T03:40:35.571+05:30Ultrasonic devices : Level<div dir="ltr" style="text-align: left;" trbidi="on">
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The operational principle of these devices is based on the phenomenon of reflection of ultrasound waves from the phase boundary separating liquid and gas. In different media the speed of sound is different. Therefore, these devices may be used for interface level measurements, and in the case when the more traditional methods do not work well or do not work at all.<br />
<br />
There are two modifications of ultrasound level measuring devices. In the first case ultrasound passes through gaseous phase; in the second case it passes through the liquid. Figure 5.15 shows a continuous ultrasound level-measuring device.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCx3aFXMahCqDld7rIn1fMj6hEXZoOFRKv1AOiXGwUv_yktKHMz42cF_HePfGEHPIE-w79Ijg3ITa3UjfM0TTPiwKX4M-W0P76iT6Kh-XSKNqjNXCQxU_UIy3hkGPW2hHu0wELLUTI9Bce/s1600/02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="262" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCx3aFXMahCqDld7rIn1fMj6hEXZoOFRKv1AOiXGwUv_yktKHMz42cF_HePfGEHPIE-w79Ijg3ITa3UjfM0TTPiwKX4M-W0P76iT6Kh-XSKNqjNXCQxU_UIy3hkGPW2hHu0wELLUTI9Bce/s400/02.png" width="400" /></a><i> </i></div>
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<i> Figure 5.15. Ultrasound level measuring device.</i></div>
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An electrical generator 1 generates electrical signals with a certain frequency. An acoustical transmitter 2 periodically sends ultrasound signals to the surface of the liquid 3. These ultrasound waves enter an acoustical receiver 4 after reflection from the surface of the liquid. After receiver the converted electrical signal is amplified in an amplifier 5 and enters a time interval counter 6 that measures the time between the transmission of a pulse and receipt of the corresponding pulse echo. Then a converter 7 converts thus measured time into a standard electrical signal 4-20 mA dc. Since an ultrasound permittivity depends on the properties of a gas, then a thermal compensation unit 8 is used to reduce the influence of temperature variation on the results of measurement. In real industrial environment pressure and chemical composition are additional factors which affect the velocity of acoustic propagation. These changes can severely affect the calibration of ultrasound devices. Therefore, additional electronic means are incorporated in these instruments to correct such changes.<br />
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<br /></div>
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<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-37918930530173414872016-09-17T03:18:00.000+05:302016-09-17T03:43:21.471+05:30Conductance devices : Level<div dir="ltr" style="text-align: left;" trbidi="on">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEwwOzqtkbOcyrx8eHFC3dAgM841TdjA3gxffjhCo5ixaKh6h_AIKzTHDI2BZmw2iLpzbAqA6HgzOkTsakDB0j3MQOfxk8G-hHm9ztT2HQVM-If4JZux334W1urhnkvrHXTodPlBVPzUMg/s1600/hitech2.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="195" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEwwOzqtkbOcyrx8eHFC3dAgM841TdjA3gxffjhCo5ixaKh6h_AIKzTHDI2BZmw2iLpzbAqA6HgzOkTsakDB0j3MQOfxk8G-hHm9ztT2HQVM-If4JZux334W1urhnkvrHXTodPlBVPzUMg/s200/hitech2.jpg" width="200" /></a>These instruments are used when there is a necessity of liquid control at one specific point or between maximum and minimum values. Their principle is based on the measurements of electrolytic conductivity of liquids. Two electrodes 1 and 2 are immersed in liquid 3, which fills a vessel 4 in Fig. 5.14. These electrodes through electric cables 5 are connected with an electric or electronic relay 6. Electrodes should be insulated from the vessel. Each of the electrodes forms an electrical circuit with the vessel through liquid. Therefore, the material of the vessel should be conductive. When liquid forms the circuit with the electrode 1, the electric relay starts to operate, and a signal is sent to a secondary device which detects that the lower limit of the level equal to <b><span style="font-size: large;">h</span><i>min</i></b> has been reached. When liquid is in contact with the electrode 2, this indicates that the upper limit of the level <b><span style="font-size: large;">h</span><i>max</i></b> has been reached.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMgilLHH8rQiW4tUqM6eCZgHBCTjdXJ1EbEFZYMYhR6-Zu_s0utyArWsY5pmRZZ2mvg01BlI9-4v-Q_AGZPudpKskCGJVv_Nq2hVsyuGoo9-qGrNL4naJaOb-RxISk8p7cOXAsUYEPFiP9/s1600/01.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMgilLHH8rQiW4tUqM6eCZgHBCTjdXJ1EbEFZYMYhR6-Zu_s0utyArWsY5pmRZZ2mvg01BlI9-4v-Q_AGZPudpKskCGJVv_Nq2hVsyuGoo9-qGrNL4naJaOb-RxISk8p7cOXAsUYEPFiP9/s320/01.png" width="320" /></a><i> </i></div>
<div style="text-align: center;">
<i>Figure 5.14. Conductance-type level system.</i></div>
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These devices may be used for an interface-level control, where one liquid is conductive, whereas the second liquid is dielectric. The advantage of conductive-type level meters is that they can be used in vessels under atmospheric or manometric (or vacuumetric) pressures. When employing electric relays, the best results may be achieved for the most of aqueous solutions of electrolytes with electrolytic resistivities lower that 20000 Ohm*cm. If one deals with liquids with low electrolytic conductivity (water, alcohol), the sensitivity of an electric circuit becomes lower, so electronically operated relays are used to increase the sensitivity of the device.<br />
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<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-17147282981642765862016-09-17T03:09:00.000+05:302016-09-17T03:52:15.680+05:30Capacitance devices : Level<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjswyj_-xLdntx5Bv1beamrd6DJpyfFIKMZPRwg9fwEqsKKdspFcE8Y73dyiLV0lZm9Tz3xvqXiF1V9sRY4kXeezNm2zUy2v-3filOrDHTaID-vHq0oO6tMWo76huTJ5cNpUNysj98g7-nl/s1600/111111.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjswyj_-xLdntx5Bv1beamrd6DJpyfFIKMZPRwg9fwEqsKKdspFcE8Y73dyiLV0lZm9Tz3xvqXiF1V9sRY4kXeezNm2zUy2v-3filOrDHTaID-vHq0oO6tMWo76huTJ5cNpUNysj98g7-nl/s200/111111.jpg" width="106" /></a></div>
Due to the difference in the dielectric constants of air and liquids, it is possible to measure level of liquids in tanks by measuring the change in the capacitance (measured between two coaxial cylinders partly immersed into the liquid) with liquid level. These devices can be used for level measurement of liquids at pressures up to 6 MPa. If liquid is conductive (specific resistance <!--[if gte mso 9]><xml>
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</xml><![endif]--><span lang="EN-AU" style="font-family: "symbol"; font-size: 12.0pt;"><span style="mso-char-type: symbol; mso-symbol-font-family: Symbol;">less than or equal to </span></span><span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;">10<sup>5</sup>-10<sup>6</sup> </span> Ohm*m), then cylinders (electrodes) are covered by an electrical insulation. Fig. 5.13 shows a schematic view of a capacitance device for level measurements of liquids.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbBgYnFb7TBz7Ezp6vW0s7jfYo4ODRGDDm09bQQ-w9xV9ZDvHYH25WPhqlGAWYJakl7FIzaKWMOZOKFPYJsdATOcSRh0gd8BM1mhKiD9LpDSlVhMZaDFPCd1tnsih1WKFb0Bh35D5bmIuJ/s1600/01.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="239" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbBgYnFb7TBz7Ezp6vW0s7jfYo4ODRGDDm09bQQ-w9xV9ZDvHYH25WPhqlGAWYJakl7FIzaKWMOZOKFPYJsdATOcSRh0gd8BM1mhKiD9LpDSlVhMZaDFPCd1tnsih1WKFb0Bh35D5bmIuJ/s320/01.png" width="320" /></a></div>
<div style="text-align: center;">
<i>Figure 5.13. Capacitance device for level measurement.</i></div>
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<br />
A tank 1 is filled with a liquid 2, which level is to be measured. Two electrodes (coaxial cylinders) 3 and 4 are immersed in this liquid. The value of capacitance for this device is determined by the two capacitances: that of the capacitor formed by the liquid and the electrodes, and the capacitor formed by air 5 and the electrodes. A measuring device 6 then measures the variation in the capacitance. In this system, the increase in the total capacitance is directly proportional to the increase of the level. This technique is best applied to nonconductive liquids, since it is necessary to avoid the problems generated by conducting materials like acids.<br />
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The following formula is taken from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 145):<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxBCzd-jKrO-_JM_Y0dUQIV3kb2F7o93eT77-Z3cNAEYqMCdMgIrbPFW8Inpw10WQlwA0pI1wXJRsUnnqe8MCKBchZX7_qH-2-zoVCsE0QMXB3PWrd1ECokcDC_fbSs1R43enRrMztvZMN/s1600/02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="161" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxBCzd-jKrO-_JM_Y0dUQIV3kb2F7o93eT77-Z3cNAEYqMCdMgIrbPFW8Inpw10WQlwA0pI1wXJRsUnnqe8MCKBchZX7_qH-2-zoVCsE0QMXB3PWrd1ECokcDC_fbSs1R43enRrMztvZMN/s400/02.png" width="400" /></a>(5.51)<br />
<br />
where,<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicsdmVOSDUDW3n9BXgr6VJUnawH-B11vGS2NLQgtfRvKkP71QWJO8qjcpEAHiQpcOWfoDGGqV4BL-WqVDhp2MWVvmaT8-B0P_n8ssA3_vHdEIqLzbLrcH7DfyAcYxjB7EPLZ1hQwdJMox6/s1600/03.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicsdmVOSDUDW3n9BXgr6VJUnawH-B11vGS2NLQgtfRvKkP71QWJO8qjcpEAHiQpcOWfoDGGqV4BL-WqVDhp2MWVvmaT8-B0P_n8ssA3_vHdEIqLzbLrcH7DfyAcYxjB7EPLZ1hQwdJMox6/s400/03.png" width="400" /></a></div>
<br />
However, for precise measurements we need to take into account that <!--[if gte mso 9]><xml>
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</xml><![endif]--><span style="font-size: large;"><span lang="EN-AU" style="font-family: "times new roman" , "serif";">ε</span><span style="font-size: x-small;"><i>air</i></span> </span>is a function of pressure, temperature and humidity: <br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJMTyMroDTg4uisfbmxhNbffoLfJt0Lx3VF6PI6-wZZH6NNHbMsBCwgHHjjCcNhJMXtK8n5o5xjCQF8Fxf0DfP3gXr3-O_GocKagw06-9qrZW9C6JGLGk6TEhyphenhyphenC9dfYPxbeN-yXLcuyVfc/s1600/04.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="80" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJMTyMroDTg4uisfbmxhNbffoLfJt0Lx3VF6PI6-wZZH6NNHbMsBCwgHHjjCcNhJMXtK8n5o5xjCQF8Fxf0DfP3gXr3-O_GocKagw06-9qrZW9C6JGLGk6TEhyphenhyphenC9dfYPxbeN-yXLcuyVfc/s320/04.png" width="320" /></a>(5.52)<br />
and<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhES3DRlSU3vm9C_Bn2mnKHs8Ngl6sRefAqYuTunrvqUlUxe3R6WLG1N2Novelc5N92qgZkISocjjeeW4Li4HKkwJGa-sH6IPSg5jesETl9p8v9X35BpZt7YW9-gSlFcXbh2kOIcrDKm-m0/s1600/05.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhES3DRlSU3vm9C_Bn2mnKHs8Ngl6sRefAqYuTunrvqUlUxe3R6WLG1N2Novelc5N92qgZkISocjjeeW4Li4HKkwJGa-sH6IPSg5jesETl9p8v9X35BpZt7YW9-gSlFcXbh2kOIcrDKm-m0/s1600/05.png" /></a>(5.53)<br />
where,<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLX8Amy5Ix4VsTvlChUgj5ZvdXdRG7PET5i7y7-n3rPWUMmpzyKMm6Iu6LDkEoF02xWo_8BFWJFVaGbfwoaF-uEqP8-Y62p_frz0jQj6WP3tBNMbHecuSRrWrDgATuY2uVRh-50FpU8Fea/s1600/06.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="73" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLX8Amy5Ix4VsTvlChUgj5ZvdXdRG7PET5i7y7-n3rPWUMmpzyKMm6Iu6LDkEoF02xWo_8BFWJFVaGbfwoaF-uEqP8-Y62p_frz0jQj6WP3tBNMbHecuSRrWrDgATuY2uVRh-50FpU8Fea/s400/06.png" width="400" /></a></div>
<br />
<u>For polar dielectrics:</u><br />
<ul style="text-align: left;">
<li>high dielectric permitivity, <span style="font-size: large;"><span lang="EN-AU" style="font-family: "times new roman" , "serif";">ε</span></span><!--[if gte mso 9]><xml>
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<li>water, acetone, ethyl, methyl alcohol, etc.</li>
</ul>
<u>For non-polar dielectrics:</u><br />
<ul style="text-align: left;">
<li>dielectric permitivity, <span style="font-size: large;"><span lang="EN-AU" style="font-family: "times new roman" , "serif";">ε</span></span><span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;"></span><span lang="EN-AU" style="font-family: "calibri" , "sans-serif"; font-size: 12.0pt;"><3, </span><span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;">F/m</span>;</li>
<li>for condensed gases such as H2, O2 and N2 1.25<span lang="EN-AU" style="font-family: "calibri" , "sans-serif"; font-size: 12.0pt;"><=</span><span style="font-size: large;"><span lang="EN-AU" style="font-family: "times new roman" , "serif";">ε</span></span><span lang="EN-AU" style="font-family: "calibri" , "sans-serif"; font-size: 12.0pt;"><</span>=1.5, F/m.</li>
</ul>
<u>For weak-polar dielectrics: </u><br />
<ul style="text-align: left;">
<li>dielectric permittivity 3<span lang="EN-AU" style="font-family: "calibri" , "sans-serif"; font-size: 12.0pt;"><=</span><span style="font-size: large;"><span lang="EN-AU" style="font-family: "times new roman" , "serif";">ε</span></span><span lang="EN-AU" style="font-family: "calibri" , "sans-serif"; font-size: 12.0pt;"><</span>=6, F/m.</li>
</ul>
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For precision measurements an additional capacitance element is submerged in liquid to compensate for changes in the liquid characteristics.<br />
<br />
<h4 style="text-align: left;">
Disadvantages of these devices are listed below:</h4>
<ul style="text-align: left;">
<li><h4 style="text-align: left;">
<span style="font-weight: normal;">these devices are not able to measure level of liquids, which have tendency to crystallise, and of very viscous liquids;</span></h4>
</li>
<li><h4 style="text-align: left;">
<span style="font-weight: normal;">they are very sensitive to the variations of dielectric properties of liquids with process conditions and the variations of capacitances of connecting cables.</span></h4>
</li>
</ul>
<br />
The range of level measurements varies from 1 to 20 m. The accuracy is equal to +/- 2.5%.<br />
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<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-65478754491592601812016-09-17T02:44:00.000+05:302016-09-17T03:58:09.170+05:30Liquid head pressure devices : Level<div dir="ltr" style="text-align: left;" trbidi="on">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmodXaNrnKCXQR7lhrvfAha43JsVdPLp4w2laL8tpX_GLzquI53zoSI0N79ORh5T-zaj6peW0n-JLa3sEKXDAXobwYsa29Ai-Wd8BaJItJ0s_j37DEd90ux7fppd0eeuo6TtNmTMyoYxtc/s1600/images.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="165" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmodXaNrnKCXQR7lhrvfAha43JsVdPLp4w2laL8tpX_GLzquI53zoSI0N79ORh5T-zaj6peW0n-JLa3sEKXDAXobwYsa29Ai-Wd8BaJItJ0s_j37DEd90ux7fppd0eeuo6TtNmTMyoYxtc/s200/images.jpg" width="200" /></a>The principle of this method is based on the measurement a hydrostatic pressure, caused by a liquid head, proportional to the level of liquid. There are several modifications of this method which are utilised in the following measuring systems:<br />
<br />
• hydrostatic differential-pressure meters;<br />
• the air-bubble tube or purging system;<br />
• the diaphragm-box system, etc.<br />
<br />
Among them the hydrostatic differential-pressure method is the most popular for level measurements in open (at atmospheric pressure) or in closed (under gauge or vacuumetric pressures) tanks. Figures 5.10 and 5.11 give us examples of these two cases. A tank 1 at atmospheric or gauge (or vacuumetric) pressure is filled with liquid 2 which level is to be measured. A ‘positive’ chamber of the differential pressure transmitter 3 is connected to the tank 1 by tubing, whereas its ‘negative’ chamber is connected to a surge tank 4 which internal diameter is greater than that of tubing. Terms ‘positive’ and ‘negative’ indicate that pressure in the second chamber is lower compared with that in the first one. This doesn’t mean that the pressure is negative. A valve 5 is used to equate pressures in these two chambers of the differential pressure gauge, in order to check its zero point. This valve must be closed during level measurements. The liquid, which fills the surge tank, should be the same as that under measurement. Left and right tubes should be close to each other, because variations of an ambient temperature will cause the same changes in liquid density in both tubes. Since the diameter of the surge tank is greater than the diameter of tubing, therefore, the liquid displaced by the membrane in the differential pressure transmitter into the surge tank will not change the level in it. To eliminate the influence of variations of process pressure P in the big tank on the results of level measurement, the upper part of the big tank is connected with the upper part of the surge tank by tubing.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDLzC7NGyIDe95A6saa_OMQhbgWl9R4qEVWJaB23KJ3giEzklccUvEfaZdhvgxez-b0-QCkb6NRyRqD9mHwPhq3lFdtLHlmVf_b4kqExVW6Wn1phuvrEtv_16Ky-Cl4xb5cd4IEVMGE47G/s1600/aaaa.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDLzC7NGyIDe95A6saa_OMQhbgWl9R4qEVWJaB23KJ3giEzklccUvEfaZdhvgxez-b0-QCkb6NRyRqD9mHwPhq3lFdtLHlmVf_b4kqExVW6Wn1phuvrEtv_16Ky-Cl4xb5cd4IEVMGE47G/s320/aaaa.png" width="226" /> </a></div>
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<i>Figure 5.10. Level measurement in an open tank. </i> </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgX9WY5MBEtIfTQ6BlZdsThNXcRz1t4eaqSTdqb7WJySzjGSBQdh-6UCS09p5CoZViNX1Rd5nlHnUA6ugPDaeo6oArCeeUKgM0KUEdls60Cxl71-v3_TDHN7QuH5Y8XRHeAboOC6np8v8BX/s1600/bbbbbbbbbbb.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgX9WY5MBEtIfTQ6BlZdsThNXcRz1t4eaqSTdqb7WJySzjGSBQdh-6UCS09p5CoZViNX1Rd5nlHnUA6ugPDaeo6oArCeeUKgM0KUEdls60Cxl71-v3_TDHN7QuH5Y8XRHeAboOC6np8v8BX/s320/bbbbbbbbbbb.png" width="216" /></a></div>
<div style="text-align: center;">
<i>Figure 5.11. Level measurement in a closed tank</i></div>
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The differential pressure measured by the differential pressure transmitter is equal to:</div>
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<br /></div>
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<br /></div>
<u>for an open tank:</u><br />
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<br /></div>
<div class="separator" style="clear: both; text-align: left;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEit8ptMh-JFNddgEs5EmpaE5yrw-M8mSkwJX594JPDd1Z6QIkRymXMFk_tO_s4l5jDXSXzh075785WRsP3TIb_wFqwCdd8kj0ww_rfB_1PvXtgrlBr3EljdLYV0eiZsVRlApDl754q6YXN_/s1600/01.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="67" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEit8ptMh-JFNddgEs5EmpaE5yrw-M8mSkwJX594JPDd1Z6QIkRymXMFk_tO_s4l5jDXSXzh075785WRsP3TIb_wFqwCdd8kj0ww_rfB_1PvXtgrlBr3EljdLYV0eiZsVRlApDl754q6YXN_/s400/01.png" width="400" /></a>(5.48)</div>
<div class="" style="clear: both; text-align: left;">
<u>for a closed tank:</u><br />
<br />
<span id="goog_2126512505"></span><span id="goog_2126512506"></span> </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifm1pb4xq05NB2PdMSf2T1EfoSvLwQaDHXXu1f5L0KtHJHJpAex7hdmoKo3sogsEmLtQrUGG5_p1ZSIwDGOWvXwa45hAJ7epGlkgNAjHYTHB559JQZJSSPIw78KvpSFIhhxPI1O-_GqH6W/s1600/02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="37" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifm1pb4xq05NB2PdMSf2T1EfoSvLwQaDHXXu1f5L0KtHJHJpAex7hdmoKo3sogsEmLtQrUGG5_p1ZSIwDGOWvXwa45hAJ7epGlkgNAjHYTHB559JQZJSSPIw78KvpSFIhhxPI1O-_GqH6W/s400/02.png" width="400" /></a>(5.49)</div>
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where, <!--[if gte mso 9]><xml>
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<span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;"><span style="font-size: large;">ρ</span><span style="font-size: x-small;"><i>liq</i></span></span> - density of the liquid in the tank under measurement, kg/m3;</div>
<span style="font-size: large;">g</span><span style="font-size: x-small;"><i>loc</i></span> - local gravitational acceleration, m/s2.<br />
<br />
Since h1 =h2 , then <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjASyBg5FFLS2WWohSql9g9oHbb82YrPAgocJs6-5NcGbahaBeHIVuY4d7ih2ja4KJkcJRjAZvC10chjkqiD7OzRD3PdLOA3-v589NthOdMp0swTgBNjtVOwi6VSzOMKpzzoDNKnyL8CCo8/s1600/03.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="60" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjASyBg5FFLS2WWohSql9g9oHbb82YrPAgocJs6-5NcGbahaBeHIVuY4d7ih2ja4KJkcJRjAZvC10chjkqiD7OzRD3PdLOA3-v589NthOdMp0swTgBNjtVOwi6VSzOMKpzzoDNKnyL8CCo8/s200/03.png" width="200" /></a>(5.50)</div>
<br />
Therefore, the output signal of the differential pressure transmitter is proportional to the <!--[if gte mso 9]><xml>
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<![endif]--><span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;">Δ</span>P , and, finally, to the liquid level H in the tank. In modern instrumentation surged tanks usually are not used. Instead, a counter-pressure P2= <span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;"><span style="font-size: large;">ρ</span><span style="font-size: x-small;"><i>liq</i></span></span><span style="font-size: large;">g</span><span style="font-size: x-small;"><i>loc </i><span style="font-size: small;">h1</span></span> is created in the ‘negative’ chamber in the case of a pneumatic differential pressure transmitter, or a counter electrical signal corresponded to the value of P2= <span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;"><span style="font-size: large;">ρ</span><span style="font-size: x-small;"><i>liq</i></span></span><span style="font-size: large;">g</span><span style="font-size: x-small;"><i>loc </i><span style="font-size: small;">h1</span></span> is generated in an electrical circuit of an electronic differential pressure transmitter.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeWzj9BR5EeZMtrMeaKi_RvrncCRHuce8MhmgH4SJU1EqA0i2RloxucLWXiYAVqK1QO-cxN5zAT67VG8pokWC5-4GFszDrzh_JegNZ5vKHAC0Br3GuMGWKb1JkrtCRZ9rbSU1mPaTSh7BS/s1600/Deltabar_FMD78_alu_PP_1.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="112" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeWzj9BR5EeZMtrMeaKi_RvrncCRHuce8MhmgH4SJU1EqA0i2RloxucLWXiYAVqK1QO-cxN5zAT67VG8pokWC5-4GFszDrzh_JegNZ5vKHAC0Br3GuMGWKb1JkrtCRZ9rbSU1mPaTSh7BS/s200/Deltabar_FMD78_alu_PP_1.jpg" width="200" /></a>Let we use an electronic differential pressure transmitter in Figures 5.10 and 5.11. It is, therefore, appropriate to describe an operational principle of the electronic force-balance transmitter. In our case it converts the differential pressure into the standard electrical signal (4-20 mA dc) and transmits this signal by distance. This type of transmitter with some modifications in its design may be used for the conversion of any process variable into the standard electrical signal. Fig. 5.12 shows an operational principle of the electronic force-balance transmitter.<br />
<br />
When the difference of pressures <span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;">Δ</span>P=P1-P2 increases, then a membrane with a disc in its centre 1 will move to the left, and through a bar 2 the force developed on this membrane will be transferred to a force bar 4. The force bar rotates clockwise around a cobalt-nickel alloy seal 3. As the result of these movements a bar 5 moves clockwise, and a ferrite disc 6 moves towards a differential transformer 7. The output signal (an electromotive force) of this differential transformer increases and is fed into an amplifier 8, which is powered by a power supply 9. This signal is amplified and rectified to a direct current, and results the standard electrical output signal of 4-20 mA dc. This rectified signal (greater than the signal corresponded to the previous<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfJOzyG72KlGpCWmWlIsLNG9H771rh3CyIjmLkirKZUUAcWik4WpaTKXJEIn-wiERuhheU-FZISG-OEhNMty6f6fLSnzO4UD1EPBonG6NZkwS_3OA9uBNvazWhYAd0Veo3dqj1LOUvJkTg/s1600/06.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="308" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfJOzyG72KlGpCWmWlIsLNG9H771rh3CyIjmLkirKZUUAcWik4WpaTKXJEIn-wiERuhheU-FZISG-OEhNMty6f6fLSnzO4UD1EPBonG6NZkwS_3OA9uBNvazWhYAd0Veo3dqj1LOUvJkTg/s320/06.png" width="320" /></a></div>
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<i>Figure 5.12. Schematic of an electronic force balance transmitter.</i></div>
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balanced position of the lever system) enters a winding 10 which is placed between poles of a permanent magnet 11 and connected with a bar 12. As the result of the interaction of magnetic fields from the winding and the magnet, the former moves to the left under the force proportional to the signal from the differential transformer 7, and hence proportional to the measured differential pressure <span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;">Δ</span>P=P1-P2 . Thus, the lever system of the transmitter is rebalanced in a new position. The output signal of the transmitter is directly proportional to the <span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;">Δ</span>P.<br />
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Moving a mechanism 14 up and down can perform an adjustment of the span of the transmitter. Zero adjustment of the transmitter (for the case when <span lang="EN-AU" style="font-family: "times new roman" , "serif"; font-size: 12.0pt;">Δ</span>P=0 , then output current should be equal to I = 4 mA dc) can be done by a mechanism 13.<br />
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<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com2tag:blogger.com,1999:blog-4918615211605852720.post-51001223466198795532016-09-16T02:12:00.000+05:302016-09-17T04:05:07.753+05:30Displacer (buoyancy) devices : Level<div dir="ltr" style="text-align: left;" trbidi="on">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDqGJ86gAsLUFFSUY3Dx1DdwX26DP1JfR_m4omA5tUtxi-QPBv90dh0yVmepXD6n3Y_zTVzSFQ2JtMa8Qe90CuwhwjYvryfdWruFuHNWhAqq6o7czzghVzra18hC187lODSGYUXdHs3KCG/s1600/displacer-level-switches-1050765.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDqGJ86gAsLUFFSUY3Dx1DdwX26DP1JfR_m4omA5tUtxi-QPBv90dh0yVmepXD6n3Y_zTVzSFQ2JtMa8Qe90CuwhwjYvryfdWruFuHNWhAqq6o7czzghVzra18hC187lODSGYUXdHs3KCG/s200/displacer-level-switches-1050765.jpg" width="179" /></a>This method is based on the application of the Archimedes' principle: every body immersed in the liquid or gas is exposed to the action of a buoyant force (sometimes called as the Archimedes' force), which acts upwards. This force is equal to the weight of the liquid, gas or vapour displaced by this body. The immersed body is called a buoy, thus giving the name to the method of measurement. Fig. 5.2 presents a schematic of this type of device.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhh5TLLvDALV7eC85a7tSfVTz_efpKnZTe8gdZhXYF8eRr7tRGhZ5FTg33AlAc4LLaUmhwy15PTox-TL0rFOeEC7lxNN25k2ryfmQp9r3v64SOqzkh9jJG72TePdZThCmFtFqEGhH966_J-/s1600/01.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhh5TLLvDALV7eC85a7tSfVTz_efpKnZTe8gdZhXYF8eRr7tRGhZ5FTg33AlAc4LLaUmhwy15PTox-TL0rFOeEC7lxNN25k2ryfmQp9r3v64SOqzkh9jJG72TePdZThCmFtFqEGhH966_J-/s400/01.png" width="400" /></a></div>
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<i>Figure 5.2. Buoyancy-type level transmitter.</i></div>
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To measure the level of liquid 1 in a tank 2 a buoy 3 is partly immersed in the liquid. When the level varies so does the resultant force acting on the buoy as follows: </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbb7s2qO-UwcXnrFlP7kieBY7Tlc4g-Uf8pX6_01v3-BK25npiyyEzz4bSN5tMg6SkAcWI6uklUSFbOht8_2LsIzUqt9c5vh_9-3MPhFBBWTuFGFP8wqIGjyCc4VQ_UwmErZeu6016CmMG/s1600/02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbb7s2qO-UwcXnrFlP7kieBY7Tlc4g-Uf8pX6_01v3-BK25npiyyEzz4bSN5tMg6SkAcWI6uklUSFbOht8_2LsIzUqt9c5vh_9-3MPhFBBWTuFGFP8wqIGjyCc4VQ_UwmErZeu6016CmMG/s1600/02.png" /></a>(5.9)</div>
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where,</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyen23a35YJY5UUQEn2wTVug_RR0xn-TXq79dTmqSutVhWcMgqx3-2RD45Wz8d-8PLsLfzZrKzkdBA48zkdlPfn2ep1oWs5V-flRh5m9EIeGraDYoiKlikYA7Td7ks2b-0WFA2z2Nc-OXR/s1600/03.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyen23a35YJY5UUQEn2wTVug_RR0xn-TXq79dTmqSutVhWcMgqx3-2RD45Wz8d-8PLsLfzZrKzkdBA48zkdlPfn2ep1oWs5V-flRh5m9EIeGraDYoiKlikYA7Td7ks2b-0WFA2z2Nc-OXR/s1600/03.png" /></a></div>
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: - gravitational force acted on the buoy, N;</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYfoCRAaODYR7YFbE6Pl1KB2JEvzMJaR2K07n-VnxKWtOwNGbyQeC5MeLY4KZROaOjxFkPm41xnusoLEBPcCPm5BOk1tpb8Z0OREQ-Ip0I-gL5D5gvCS7TP7IWNF2Cc7foPNSjsLR3OU3A/s1600/04.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYfoCRAaODYR7YFbE6Pl1KB2JEvzMJaR2K07n-VnxKWtOwNGbyQeC5MeLY4KZROaOjxFkPm41xnusoLEBPcCPm5BOk1tpb8Z0OREQ-Ip0I-gL5D5gvCS7TP7IWNF2Cc7foPNSjsLR3OU3A/s1600/04.png" /></a></div>
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: - the Archimedes’ force acted on the buoy, N ;</div>
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<span style="font-size: large;">m</span><i><span style="font-size: x-small;">b </span></i><span style="font-size: small;">: - mass of the buoy, kg ;</span></div>
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<span style="font-size: small;"><span style="font-size: large;">g</span><span style="font-size: x-small;"><i>loc </i><span style="font-size: small;">: - local gravitational acceleration, m/s2;</span></span></span></div>
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<span style="font-size: small;"><span style="font-size: x-small;"><span style="font-size: small;">:- density of the liquid and the gas (or vapour) above it, respectively, kg/m3;</span></span></span></div>
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<span style="font-size: small;"><span style="font-size: x-small;"><span style="font-size: small;"><span style="font-size: large;">S</span><span style="font-size: x-small;"><i>b</i></span> : - a horizontal cross-section area of the buoy, m2 ;</span></span></span></div>
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<span style="font-size: small;"><span style="font-size: x-small;"><span style="font-size: small;"> </span></span> </span></div>
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<span style="font-size: small;"> :- parts of buoy length in the liquid and in the gas above it, respectively, m;</span></div>
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(5.10)</div>
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Since the Archimedes’ force acting from the gas on the buoy is negligible comparing with that from the liquid, and the gravitational force is constant, then the resultant force is proportional to </div>
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and, hence, to the level of the liquid.</div>
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The displacer element, buoy, is a cylinder of a constant cross-section area, and its density is greater than that of the liquid. The buoy moves up or down, depending on the level variation. The resultant force through a lever 4 is converted by a force-balance or electronic transmitter 5 to a proportional pneumatic (20-100 kPa) or electrical (4-20 mA dc) signal, which is transmitted by the distance. It means that for each value of the level in the tank will correspond the certain value of an output signal. The length, diameter, material of the buoy and transmission ratio can be changed to suit various spans and various liquids. These instruments are used for measurements of liquid level and interface providing the level to vary within the length of the buoy, and for density measurements providing the buoy is fully immersed in liquid in the entire range of measured densities.<br />
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It is appropriate now to consider an operational principle of a pneumatic transmitter, which is used for converting level variations into the standard pneumatic signal. To be more precise, these transmitters can be used to convert a mechanical motion (which may be caused by the variation of any process variable) into the standard pneumatic signal. Fig. 5.3 shows a schematic view of the pneumatic transmitter.<br />
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When level of the liquid goes up, the Archimedes’ force moves the buoy 1 in the same direction. A membrane 2 separates the measuring part of the pneumatic transmitter from the part with a high process pressure in the tank where the level is to be measured. The motion of the buoy through levers 3 (rotates clockwise) and 4 (rotates clockwise) transmits to the force bar 5 (rotates clockwise). The force bar is connected with the flapper 6, which approaches to the nozzle 7. The pressure supplied to a pneumatic amplifier 8 is equal to 140 kPa. The pressure from this amplifier is fed to the nozzle, and then to atmosphere. When the flapper approaches to the nozzle, the pressure in the nozzle increases. This pressure enters the pneumatic relay in the pneumatic amplifier, where it is amplified, and so the value of the output pressure increases. The output pressure is transmitted to a measuring or controlling instrument, and is applied to the feedback bellows 9, thus increasing the counterclockwise moment of force acting from the lever 10 (rotates clockwise) on the force bar 5. This moment of force is sufficient to restore the force bar to the balance. When the balance has reached the output pressure is linearly related to the value of the measured liquid level. A gain adjustment holder 11 is used for the variation of the measuring range. An additional weight 12 is used for damping the vibration of levers. Zero adjustment can be achieved by the spring 13.</div>
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<h3 style="text-align: left;">
1.1 Flapper-nozzle system</h3>
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Fig. 5.3 shows a
flapper-nozzle system and Fig. 5.4 shows a relationship between the
output pneumatic signal and the distance between the flapper and the
nozzle.<br />
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The diameter of the supply restriction 1 is 0.2-0.3 mm,
whereas that of the nozzle 2 is 0.8 mm. The distance between the flapper
3 and the nozzle determines the output pressure in the chamber between
them. This pressure is measured by the pressure gauge 4. Small nozzle
diameters increase gain, but also increase the danger of clogging. Large
nozzle diameters increase the air consumption. The variation of the
nozzle clearance by 0.04 mm gives the change in the output pressure from
20 to 100 kPa. Formulars below are taken from(from Bentley J. P.
Principles of Measurement Systems, Longman, 1995, p. 315):<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5BzZ5DZNmEefPEmLhTc-km6cG0Qk-n7jY2PwvX-XU-sIx1uj457qdah5-974cgyF00yldXhOO5ILwy-7RoeKdo7x9oFTLQFfq8sbphWNlx4Tu4kB5SxlRcysVt9fDGd4hyPPYX6y3sS8M/s1600/02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="388" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5BzZ5DZNmEefPEmLhTc-km6cG0Qk-n7jY2PwvX-XU-sIx1uj457qdah5-974cgyF00yldXhOO5ILwy-7RoeKdo7x9oFTLQFfq8sbphWNlx4Tu4kB5SxlRcysVt9fDGd4hyPPYX6y3sS8M/s400/02.png" width="400" /></a></div>
<div style="text-align: center;">
<i>Figure 5.3. A pneumatic transmitter.</i></div>
<div style="text-align: center;">
<i><br /></i></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjil1RYOXsDsihPkh18x3aRt4G-lbDiIES1PfCsZl6R9sdWWPBBY9LAd9rzjNjXnTVpLyLDvQr_CjfZ9rJmyqE2bERWtWkxPX_Rao_z4CMfcBOJ42QirwVbbOUGOlN5MyHEOr_yKcouEYHN/s1600/03.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="246" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjil1RYOXsDsihPkh18x3aRt4G-lbDiIES1PfCsZl6R9sdWWPBBY9LAd9rzjNjXnTVpLyLDvQr_CjfZ9rJmyqE2bERWtWkxPX_Rao_z4CMfcBOJ42QirwVbbOUGOlN5MyHEOr_yKcouEYHN/s400/03.png" width="400" /></a></div>
<div style="text-align: center;">
<i>Figure 5.4. A flapper-nozzle system.</i></div>
<div style="text-align: center;">
<br /></div>
<div style="text-align: left;">
1 - restriction, Dor = 0.2 mm; 2 - nozzle, Dn = 0.8 mm; 3 - flapper.<i> </i></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijBfsPWkyn-PEehfCGw05olm3UmnhgA8x9jFQd0PskQZUIvvpEeNUfveeiKqzdcVtr9FJ8KDIcnsbjkRoEzQxuEPaKn2R_ZlGGrgka0SzpQ-Gb_UT6_cas1CzY5yTcBMIWmSmsFpzvkrq4/s1600/04.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="226" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijBfsPWkyn-PEehfCGw05olm3UmnhgA8x9jFQd0PskQZUIvvpEeNUfveeiKqzdcVtr9FJ8KDIcnsbjkRoEzQxuEPaKn2R_ZlGGrgka0SzpQ-Gb_UT6_cas1CzY5yTcBMIWmSmsFpzvkrq4/s400/04.png" width="400" /></a></div>
<br />
<br />
<div style="text-align: center;">
<i>Figure 5.5. Nozzle air pressure vas distance between the flapper and the nozzle.</i></div>
<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0lMTpk2gY9L60VwMMNPsuDXXADGeg8Y9tFNcTdZuyyWh_rn4GABJEs3VRDXspbFPelaL_ZhL_hTP_eSC3_JjXc16AJN28do1eNYvHF_TaLU1bAxHMezMCQj0MNESG2AaNb25Qwu-E3lnv/s1600/05.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="162" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0lMTpk2gY9L60VwMMNPsuDXXADGeg8Y9tFNcTdZuyyWh_rn4GABJEs3VRDXspbFPelaL_ZhL_hTP_eSC3_JjXc16AJN28do1eNYvHF_TaLU1bAxHMezMCQj0MNESG2AaNb25Qwu-E3lnv/s400/05.png" width="400" /></a></div>
<br />
For the steady state condition:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzlHwZrN03V6lWeBcJg9LUmlHIXeIq61_-QL7mmeHtByp-Y3gXX7C1fROhnZqc80tXSJMwQjppN4tkd3QoFO8wcdlbHv3hwj023dM6wvm9K6NCy2pfn2k6TMHF0FIyFxj-5gahPYVcKAV6/s1600/06.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzlHwZrN03V6lWeBcJg9LUmlHIXeIq61_-QL7mmeHtByp-Y3gXX7C1fROhnZqc80tXSJMwQjppN4tkd3QoFO8wcdlbHv3hwj023dM6wvm9K6NCy2pfn2k6TMHF0FIyFxj-5gahPYVcKAV6/s1600/06.png" /></a></div>
and (from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 316):.<br />
<br />
So,<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwHCZjHwSZeipH4kMFJe12tIVPhhrk_NOjROQJkldLmmNQ_DjIQswVMnTYGVgxTXa0QOVcnHKlgw3V2xPgmm_ZlDi6unOJdK-U0-l9N1fLhTZ36M9BiAIM-2aB82nFxFvOLZQxroDdS6_3/s1600/07.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwHCZjHwSZeipH4kMFJe12tIVPhhrk_NOjROQJkldLmmNQ_DjIQswVMnTYGVgxTXa0QOVcnHKlgw3V2xPgmm_ZlDi6unOJdK-U0-l9N1fLhTZ36M9BiAIM-2aB82nFxFvOLZQxroDdS6_3/s1600/07.png" /></a>, and<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJPEVo_L5XfzEgYv3GgtoJniZpZ7YEr5ApOLAPkWV8FGtdTHB8Byfky9dDjQwlEk47dQVe7WUeTPEn0PNPLwf1qjgpQ6RdMFuhwE20VNAKoLJm9Gc5gyr_I8p0LiU2IQGEbzQ766Hf9nkO/s1600/08.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJPEVo_L5XfzEgYv3GgtoJniZpZ7YEr5ApOLAPkWV8FGtdTHB8Byfky9dDjQwlEk47dQVe7WUeTPEn0PNPLwf1qjgpQ6RdMFuhwE20VNAKoLJm9Gc5gyr_I8p0LiU2IQGEbzQ766Hf9nkO/s1600/08.png" /></a> (5.18)</div>
Finally,<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnIKCGNIlsR30MS0qc1skxe_BBXBxkFdaRa6SvGSZ2LVOzSHtZ28l0HMdIQy2Ellj-pL4NW9Hd2EDKpYAXYWMkEAqLcyyRxfBhQgCnCAowltvS357I2VTtmOP6lXZVWneKL-K-WofPxYBj/s1600/09.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnIKCGNIlsR30MS0qc1skxe_BBXBxkFdaRa6SvGSZ2LVOzSHtZ28l0HMdIQy2Ellj-pL4NW9Hd2EDKpYAXYWMkEAqLcyyRxfBhQgCnCAowltvS357I2VTtmOP6lXZVWneKL-K-WofPxYBj/s1600/09.png" /></a>(5.19)<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpjb2pKmE2-kO1u8hOYyUYrhk2k8r3LF7197Hv4Jgd81rdlwZek6sY2Ruxx-yYxMsTjYMgm4IttZZ7vRHvV03poaPIVdY7njPV87daB99fgeIxI3S-xZEMWHyMpcZgFoJZPbF5gV32BaFf/s1600/10.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="217" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpjb2pKmE2-kO1u8hOYyUYrhk2k8r3LF7197Hv4Jgd81rdlwZek6sY2Ruxx-yYxMsTjYMgm4IttZZ7vRHvV03poaPIVdY7njPV87daB99fgeIxI3S-xZEMWHyMpcZgFoJZPbF5gV32BaFf/s400/10.png" width="400" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-WQtYw_3UZJ_gQrwp9y2RTHuYqW9X_oJomz_aOinVQSJ5q9EMFUfesiu6NPbmEz9H4OpIwxFXiJe9OS3SiWxhC2gXWjwOTGOfjvZTeOtKkPz7Hww-YIJlNC4znMrc7gku_S2jU2yWS3QV/s1600/11.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="171" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-WQtYw_3UZJ_gQrwp9y2RTHuYqW9X_oJomz_aOinVQSJ5q9EMFUfesiu6NPbmEz9H4OpIwxFXiJe9OS3SiWxhC2gXWjwOTGOfjvZTeOtKkPz7Hww-YIJlNC4znMrc7gku_S2jU2yWS3QV/s400/11.png" width="400" /></a></div>
<h3 style="text-align: left;">
</h3>
<h3 style="text-align: left;">
1.2 . Pneumatic relay amplifier</h3>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgac9DOKJRSmMzf6UGjfxmiMfxBhgSZWOJTC1uJIT4ouYIaUotg7I7x_bFmeCbwhx9t5l01ZoTW03jkyBidrpsT-ptFQoFBxaDZZ7x4yDIw44VXZbpv22Nk7Z9bubooCQpzJGBDUgvJGxPJ/s1600/12.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgac9DOKJRSmMzf6UGjfxmiMfxBhgSZWOJTC1uJIT4ouYIaUotg7I7x_bFmeCbwhx9t5l01ZoTW03jkyBidrpsT-ptFQoFBxaDZZ7x4yDIw44VXZbpv22Nk7Z9bubooCQpzJGBDUgvJGxPJ/s1600/12.png" /></a>(5.20)<br />
and <br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiozk_ryuH2w7mQ9nErZ2MgiyQkggRsjFni3o1-TTXgiGXQrpg4CQEKnbz03YTE_tkFpNRgKPCkey5Uz32GxQmvaJ2n0cuiDhzl9MFmAxkhNAplA-vwjnrLVyusMkgbOGmQ704N5SBi1FSb/s1600/13.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiozk_ryuH2w7mQ9nErZ2MgiyQkggRsjFni3o1-TTXgiGXQrpg4CQEKnbz03YTE_tkFpNRgKPCkey5Uz32GxQmvaJ2n0cuiDhzl9MFmAxkhNAplA-vwjnrLVyusMkgbOGmQ704N5SBi1FSb/s1600/13.png" /></a>(5.21)<br />
<br />
So,<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSe1bsq9fNFxymV-6r_5Yf91YUHGQC_fCfMpDBqH6Z0rcMQ2A5BNsTFtHm66jz35WkBcOO9jIziouXiYmbJAweEoetGmPrAo98JwjocvZ8kYMzozlVR9OtZstAgdQdG2k9gFbmQwRIHaAx/s1600/14.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSe1bsq9fNFxymV-6r_5Yf91YUHGQC_fCfMpDBqH6Z0rcMQ2A5BNsTFtHm66jz35WkBcOO9jIziouXiYmbJAweEoetGmPrAo98JwjocvZ8kYMzozlVR9OtZstAgdQdG2k9gFbmQwRIHaAx/s1600/14.png" /></a>(5,22)<br />
<br />
where, <br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhu2r3V5Xw7YhU4cubJNSWSOOmjKkUImUMpLpWr9VIyXTPKiRNSKZRECdokUqMPOxoJQ8fTKwp2R7YgCovcvBPetfGvinG3tOvRV4_82kLqLzYRNyzqWqm2SGPwEuglZ86W4XkcI2FH-13o/s1600/15.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="135" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhu2r3V5Xw7YhU4cubJNSWSOOmjKkUImUMpLpWr9VIyXTPKiRNSKZRECdokUqMPOxoJQ8fTKwp2R7YgCovcvBPetfGvinG3tOvRV4_82kLqLzYRNyzqWqm2SGPwEuglZ86W4XkcI2FH-13o/s400/15.png" width="400" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: left;">
Steady-state sensitivity: </div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzRjwh0HKLJlqjSQ6gcNrh4-nvSERg8PotjqcMRgMhbdkqOyvqgWezAug2ltCeBHaNiXDpyd4t6zn2MNixSnACi14xL3BWrIZLATd2rLZ4bgCgOpkIRudOao-RkRDXdnEWZB0JOwZfHgri/s1600/16.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzRjwh0HKLJlqjSQ6gcNrh4-nvSERg8PotjqcMRgMhbdkqOyvqgWezAug2ltCeBHaNiXDpyd4t6zn2MNixSnACi14xL3BWrIZLATd2rLZ4bgCgOpkIRudOao-RkRDXdnEWZB0JOwZfHgri/s1600/16.png" /></a> (5.23)<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitICqwLEX2u9Td0Mbd4SQVGa-H_u4eZFpqMfhTOOCUJbVu4c8Sqef8imDLiOWJLWzZle0m2sUWRY24dFovnljiTFrmG7hikxRXqfH53Akjkk1lxmpIllUrMwT-REkEGG1_-zTZBAXjRGCi/s1600/17.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="351" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitICqwLEX2u9Td0Mbd4SQVGa-H_u4eZFpqMfhTOOCUJbVu4c8Sqef8imDLiOWJLWzZle0m2sUWRY24dFovnljiTFrmG7hikxRXqfH53Akjkk1lxmpIllUrMwT-REkEGG1_-zTZBAXjRGCi/s400/17.png" width="400" /></a></div>
<div style="text-align: center;">
<i>Figure 5.6. Pneumatic relay amplifier (from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 317):.</i></div>
1 - flapper;<br />
2 - nozzle;<br />
3 - orifice;<br />
4 - diaphragm; <br />
5 - double vent;<br />
6 - transmission line.<br />
<br />
<br />
<h3 style="text-align: left;">
<i>1.3</i>. Simplified model of pneumatic torque-balance transmitter</h3>
(from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 319-320):<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEMFDxv-vaAGoE1UZ_3D8eA9ejleOpcTYJDheqp2ovbo1sWPSUHi1l0PU5GjZBDj7ml1L2SaOgBMFu75TEHvo9XqWUn56P6Ru7G0cnVSyowbU8w4mF2u4pH3qms7iKz8vQOh4znCE3iMQ1/s1600/18.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="331" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEMFDxv-vaAGoE1UZ_3D8eA9ejleOpcTYJDheqp2ovbo1sWPSUHi1l0PU5GjZBDj7ml1L2SaOgBMFu75TEHvo9XqWUn56P6Ru7G0cnVSyowbU8w4mF2u4pH3qms7iKz8vQOh4znCE3iMQ1/s400/18.png" width="400" /></a></div>
<div style="text-align: center;">
<i>Figure 5.7. Pneumatic torque-balance transmitter.</i></div>
<br />
1 – beam;<br />
2 - pivot;<br />
3 - negative feedback bellows;<br />
4 - nozzle;<br />
5 - flapper;<br />
6 -zero adjustment spring;<br />
7 - pneumatic relay amplifier.<br />
Anticlockwise moments:<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEib3-z1PGJ50FZkx-_SXoDmPVzn3L2Uh_Uc2fIGvYtP0ZwA23Wfimy_78A8m_wFtKJz76ovu4bEJWhlsRR-n3g6uM8GGgaWtVwpWu-WdbaezVnGyIQLdl6-Pb5A1EaGgrRUajo-gftUAGSd/s1600/19.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEib3-z1PGJ50FZkx-_SXoDmPVzn3L2Uh_Uc2fIGvYtP0ZwA23Wfimy_78A8m_wFtKJz76ovu4bEJWhlsRR-n3g6uM8GGgaWtVwpWu-WdbaezVnGyIQLdl6-Pb5A1EaGgrRUajo-gftUAGSd/s1600/19.png" /></a> (5.24)<br />
<br />
Clockwise moment:<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKdxB_rWkGdvnTaat6v3QFHKtXDXFmRMcMIHtGYUOnHVxbf7_PJVd3G1buviOEBTCnLRAbJfxdYZNRT8qLN98erqtxxeOW4044WFhO14TGvwcZWf1KH5ZrVlKtDQTS4XwQbHe_0jx4z2UY/s1600/20.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKdxB_rWkGdvnTaat6v3QFHKtXDXFmRMcMIHtGYUOnHVxbf7_PJVd3G1buviOEBTCnLRAbJfxdYZNRT8qLN98erqtxxeOW4044WFhO14TGvwcZWf1KH5ZrVlKtDQTS4XwQbHe_0jx4z2UY/s1600/20.png" /></a> (5.25)<br />
<br />
<h4 style="text-align: left;">
a). Condition of a perfect torque balance:</h4>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<span id="goog_533479632"></span><span id="goog_533479633"></span> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm-T43GDNKleGUBbVpzcZ_tM4zNhPf8JlN5n3CS7PB1T54OXu3HTNdT_dsH2rp3-CoSbD2f1qIfL8xhemTPFPnTEQu7BLSlQ8pTLEtr8Gmn6rfQp9VvOIUawwlEq9lVAWCwI2QdZWxnnRS/s1600/21.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm-T43GDNKleGUBbVpzcZ_tM4zNhPf8JlN5n3CS7PB1T54OXu3HTNdT_dsH2rp3-CoSbD2f1qIfL8xhemTPFPnTEQu7BLSlQ8pTLEtr8Gmn6rfQp9VvOIUawwlEq9lVAWCwI2QdZWxnnRS/s1600/21.png" /></a><br />
<br />
(5.26)<br />
<br />
<br />
<br />
A simple model for a torque-balance transmitter:<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglbJpr4-G7r37dm5EaN9vGGEmmK8eM0oiaN2sIbPZ_8AAb2wdpnGAF6Q3VYL7HTlMbqK2SScrA3y6BV4iEoV7auitK6VtcZ3iHIbDcTOvQVk4S1WFp9KTxtLkcnsWZUHAYPjmDdQtHdxnn/s1600/22.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglbJpr4-G7r37dm5EaN9vGGEmmK8eM0oiaN2sIbPZ_8AAb2wdpnGAF6Q3VYL7HTlMbqK2SScrA3y6BV4iEoV7auitK6VtcZ3iHIbDcTOvQVk4S1WFp9KTxtLkcnsWZUHAYPjmDdQtHdxnn/s1600/22.png" /></a></div>
<br />
. (5.27)<br />
<br />
<br />
<br />
<br />
The sensitivity of the transmitter<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXc25psnHWWo6aVnERPlkBXEo1W3t4L16hzl4QXW2IqIJTDyAFGoNrxFZCj7ueQGw2l0GMISK1vnZEdOqHpOmVL5EA7qjyvFD37P9xXONowjrhKI6Iu5OZvaxnx2CS-AIRdeRucmxjs2yl/s1600/23.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXc25psnHWWo6aVnERPlkBXEo1W3t4L16hzl4QXW2IqIJTDyAFGoNrxFZCj7ueQGw2l0GMISK1vnZEdOqHpOmVL5EA7qjyvFD37P9xXONowjrhKI6Iu5OZvaxnx2CS-AIRdeRucmxjs2yl/s1600/23.png" /></a></div>
<br />
<br />
<br />
. (5.28)<br />
<br />
<br />
<u>Example:</u></div>
<div style="text-align: left;">
</div>
<div style="text-align: left;">
</div>
<div style="text-align: left;">
If </div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizwBAkYUVldXdJoMMhBl0M-mqF8w1hkTj4CV5elJV1hB6Ea_1c4wbFR7twZjzVIMNVc4JeCEE0tFqdcnQT0aQt81CHlsCrymnXhZZsml3LFseMOQBhIPB9r1ZG6m9qscG4s1F6Dfs3_H-6/s1600/24.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="56" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizwBAkYUVldXdJoMMhBl0M-mqF8w1hkTj4CV5elJV1hB6Ea_1c4wbFR7twZjzVIMNVc4JeCEE0tFqdcnQT0aQt81CHlsCrymnXhZZsml3LFseMOQBhIPB9r1ZG6m9qscG4s1F6Dfs3_H-6/s400/24.png" width="400" /></a></div>
<div style="text-align: left;">
then<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdBp-wzzBy9xQEZlWS9XwcFd5SdUlLzv23rad7u2hDusOxxv92WuFFQm-cLyDcoEEHRWudtL0unwW27hGjfJ53_7jE2iVqlxTGUgiEE2nkogb3oEg3pi6mXvHvOiOv-boGvolJnA-gVDMG/s1600/25.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="40" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdBp-wzzBy9xQEZlWS9XwcFd5SdUlLzv23rad7u2hDusOxxv92WuFFQm-cLyDcoEEHRWudtL0unwW27hGjfJ53_7jE2iVqlxTGUgiEE2nkogb3oEg3pi6mXvHvOiOv-boGvolJnA-gVDMG/s400/25.png" width="400" /></a></div>
<h4 style="text-align: left;">
b). Condition of imperfect torque balance:</h4>
Anticlockwise moments:<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjM5M8zmtFhJPYvULKEvd8tpyDQxqSP5IZ9P23HhHUxs7mofr10r_r7fZFgV8nE2yKl5dDicmbjP3pbBONatUarGSqFGZqPaq5iIjIS6v0cChJ4SeBAazYFj5qIVM1hHy4JQc93k8suGh1l/s1600/26.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjM5M8zmtFhJPYvULKEvd8tpyDQxqSP5IZ9P23HhHUxs7mofr10r_r7fZFgV8nE2yKl5dDicmbjP3pbBONatUarGSqFGZqPaq5iIjIS6v0cChJ4SeBAazYFj5qIVM1hHy4JQc93k8suGh1l/s1600/26.png" /></a></div>
<br />
. (5.29)<br />
<br />
<br />
Clockwise moment:<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQIysX33NOSjD-YQYU79KxbNIVIvD2ABSZOW9sYifMKT9Foh6y9umRu7-Ozt4QdhfDW4clPKwVHyNzgDxkpn7MG188UAyZgwR4fTuJbyXgdPB9xSeGYF7vhW0fv1fXITvNHvgCtvDfRWfz/s1600/27.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQIysX33NOSjD-YQYU79KxbNIVIvD2ABSZOW9sYifMKT9Foh6y9umRu7-Ozt4QdhfDW4clPKwVHyNzgDxkpn7MG188UAyZgwR4fTuJbyXgdPB9xSeGYF7vhW0fv1fXITvNHvgCtvDfRWfz/s1600/27.png" /></a></div>
(5.30)<br />
<br />
. <br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv0sJxc1OSz-Wt7r9nz-ajhOX88J1-wvqZfMZOu290Fs_TKC3CeSu4Y4RAZhPZzQ_B2GFG3twtIS5-Sf9IsuFJaUP6nJ-lPf8LpXdhyzXDI7KCrEMS9WRnsmqHnSr08MAQMmIcO3nFUEX4/s1600/28.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="52" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv0sJxc1OSz-Wt7r9nz-ajhOX88J1-wvqZfMZOu290Fs_TKC3CeSu4Y4RAZhPZzQ_B2GFG3twtIS5-Sf9IsuFJaUP6nJ-lPf8LpXdhyzXDI7KCrEMS9WRnsmqHnSr08MAQMmIcO3nFUEX4/s400/28.png" width="400" /></a>(5.31)<br />
<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWU8sSYJo-UP2CziqMJwKFpEsb93wDuVMo-lq6PdHh2TY4TOO_nGsd1nUcKtUJwiRfyUU8OltOHgW6P1LsOkdtm9I_-DAFf38hv2hggqdmBebEiawXdntl31_W4vvIYxFWa8CVZdSo1eIQ/s1600/29.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWU8sSYJo-UP2CziqMJwKFpEsb93wDuVMo-lq6PdHh2TY4TOO_nGsd1nUcKtUJwiRfyUU8OltOHgW6P1LsOkdtm9I_-DAFf38hv2hggqdmBebEiawXdntl31_W4vvIYxFWa8CVZdSo1eIQ/s1600/29.png" /></a></div>
<br />
. (5.32)<br />
<br />
<br />
<br />
An accurate model for torque-balance transmitter is as follows:<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCio4pnbAwhC6Dl-xWNEM7BPElD5qs6p440Su0hUlfjTx1ElS1sbLpHdt6u3rogatQAg9OcbG8pNg95Z-J7IHWCc1FzNDrp1Y9D_T46F9Zx9PLPyL0TXZtBtDX9LnHBpfbJedl2oIEH_8b/s1600/30.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCio4pnbAwhC6Dl-xWNEM7BPElD5qs6p440Su0hUlfjTx1ElS1sbLpHdt6u3rogatQAg9OcbG8pNg95Z-J7IHWCc1FzNDrp1Y9D_T46F9Zx9PLPyL0TXZtBtDX9LnHBpfbJedl2oIEH_8b/s1600/30.png" /></a> (5.33)<br />
<br />
where,<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiScWqe_kQtZDxkrHkqUtgRd17ZC-BurnE9IfBY1x0buoDL7Wlw4GX3gnTNazhDmUQFRSprHQ18K40Tp0hiDbfsq-47r_71LFnZuKPpwcKTJvIshVOD4jGbbZUqTX8FbBGCBorT1WB1s-7N/s1600/31.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="195" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiScWqe_kQtZDxkrHkqUtgRd17ZC-BurnE9IfBY1x0buoDL7Wlw4GX3gnTNazhDmUQFRSprHQ18K40Tp0hiDbfsq-47r_71LFnZuKPpwcKTJvIshVOD4jGbbZUqTX8FbBGCBorT1WB1s-7N/s400/31.png" width="400" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_vBCaadI7j-OQlygHl4b4rkDAGP52e7tP2qukmSHZXUf3RKt5_HIq4637h4Uy3Yb_L314htT_KbTZ33rU1mNeapVOiA0qYwbyeRlRexwSZ1BZ0j1LhIu1opQLb2d30EuRlE8O579KtPXn/s1600/32.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_vBCaadI7j-OQlygHl4b4rkDAGP52e7tP2qukmSHZXUf3RKt5_HIq4637h4Uy3Yb_L314htT_KbTZ33rU1mNeapVOiA0qYwbyeRlRexwSZ1BZ0j1LhIu1opQLb2d30EuRlE8O579KtPXn/s400/32.png" width="400" /></a></div>
<div style="text-align: center;">
<i>Figure 5.8. Block-diagram for a pneumatic torque-balance transmitter.</i></div>
<br />
<br />
<h3 style="text-align: left;">
1.4. Simplified model of pneumatic differential pressure transmitter</h3>
(from Bentley J. P. Principles of Measurement Systems, Longman, 1995, p. 321-322):<br />
<br />
According to Fig. 5.9 the resultant force on the diaphragm is as follows:<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWsCHYzlxvjaWhzfpRc52XTsDrchdrydlWn8Y05chCmjrL8VRXdX9OQ-Jgfl-2HZ67MNpduqEcGO71mXsI_f452oTHTTNfEV3ev9XCOeMl8fIjQjOsmLuKOlUjK5v-GdYKQe4ou2AbR_Wu/s1600/33.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWsCHYzlxvjaWhzfpRc52XTsDrchdrydlWn8Y05chCmjrL8VRXdX9OQ-Jgfl-2HZ67MNpduqEcGO71mXsI_f452oTHTTNfEV3ev9XCOeMl8fIjQjOsmLuKOlUjK5v-GdYKQe4ou2AbR_Wu/s1600/33.png" /></a> (5.34)<br />
<br />
Clockwise moment on the force beam due to the action of :<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3csJPednVRxvHomz-wI3U6KVf22bSw3HmIgslDKOssHbGEcNvx1vr43YzpHc4mW5ddvzw2Pj6N58ACumXeJs9kVfiqOnAwCmBd6q_73PI5YeTDO6vfSCDam3LmXIGOZ-FTc5jcmTa9fQh/s1600/34.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3csJPednVRxvHomz-wI3U6KVf22bSw3HmIgslDKOssHbGEcNvx1vr43YzpHc4mW5ddvzw2Pj6N58ACumXeJs9kVfiqOnAwCmBd6q_73PI5YeTDO6vfSCDam3LmXIGOZ-FTc5jcmTa9fQh/s1600/34.png" /></a>(5.35)<br />
<br />
Anticlockwise moment on the force beam due to the action of the span nut:<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhM0YxBKEVvol-XjSkw4Wyr9LK3979CNAE6PJYOAbeRSG4AKYOCj2Vmsv8E7mJ7vc2trknDMMlpS1FhY7xhnCgm2fZtIfeOytq5KHh3J3XzBZ-QpyFzMYy72LGbVNMY464RKLZ5eaMHeaas/s1600/35.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhM0YxBKEVvol-XjSkw4Wyr9LK3979CNAE6PJYOAbeRSG4AKYOCj2Vmsv8E7mJ7vc2trknDMMlpS1FhY7xhnCgm2fZtIfeOytq5KHh3J3XzBZ-QpyFzMYy72LGbVNMY464RKLZ5eaMHeaas/s1600/35.png" /></a>(5.36)<br />
<br />
For the condition of balance:<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX5V0rHivZpgsZKEfWW65gYkoX7AwZc6Bl2C-eDnRpgsFT8SQuWw0UYDm4LQBW9eV7JhcXpm74vKXO2aeili9qZKnYccTWhp51XfaDyXMIDlA7G_r9OsBloL7rScPhrr4d89Lp_exID6rq/s1600/36.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX5V0rHivZpgsZKEfWW65gYkoX7AwZc6Bl2C-eDnRpgsFT8SQuWw0UYDm4LQBW9eV7JhcXpm74vKXO2aeili9qZKnYccTWhp51XfaDyXMIDlA7G_r9OsBloL7rScPhrr4d89Lp_exID6rq/s1600/36.png" /></a>(5.37) or<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjo3qUCEYd6BUcfG49uLg1cHql7EWQpxV5Q8m-VFJQsSb4taRO2PCLDK9LbP2OsaWjvSwUV_hzbDbQMmFsNCKDYBd468jd6CvV9JiwuDpTUBMOVeFfQmQ5qh3KTGOoszp-dJTT_UZnbdd_e/s1600/37.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjo3qUCEYd6BUcfG49uLg1cHql7EWQpxV5Q8m-VFJQsSb4taRO2PCLDK9LbP2OsaWjvSwUV_hzbDbQMmFsNCKDYBd468jd6CvV9JiwuDpTUBMOVeFfQmQ5qh3KTGOoszp-dJTT_UZnbdd_e/s1600/37.png" /></a>(5.38)<br />
<br />
Anticlockwise moment produced by the span nut on the feedback beam:<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFgmbvJzHEWSz_L9VYzcBzbn3cTGSs_a4TpLtgr95VLPGbnDMH1QHkFLyB7ReAPHE4bsabIVYJggr7B26yn1JqA5_Gvs_CxOFzn8Pdm-SqFH1J7BE1-3N23pJHyFSb5Q_AXCH8HgM_On6l/s1600/38.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFgmbvJzHEWSz_L9VYzcBzbn3cTGSs_a4TpLtgr95VLPGbnDMH1QHkFLyB7ReAPHE4bsabIVYJggr7B26yn1JqA5_Gvs_CxOFzn8Pdm-SqFH1J7BE1-3N23pJHyFSb5Q_AXCH8HgM_On6l/s1600/38.png" /></a> (5.39)<br />
<br />
Anticlockwise moment produced by the zero spring force on the feedback beam:<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpTGyfS75bsr0Vk7k9HXHW5eetQr9zdLkXI6Aj0AlfX7ZNMxgrbU98_-3hny1u5-L105PopwCTNOlEakjxzjFUMG64VwFG-M7XEkvO5vyRTMJH5xLoeFpfGIICPU8P1ZSTT4atlc45G_Yg/s1600/39.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpTGyfS75bsr0Vk7k9HXHW5eetQr9zdLkXI6Aj0AlfX7ZNMxgrbU98_-3hny1u5-L105PopwCTNOlEakjxzjFUMG64VwFG-M7XEkvO5vyRTMJH5xLoeFpfGIICPU8P1ZSTT4atlc45G_Yg/s1600/39.png" /></a> (5.40)<br />
<br />
Clockwise moment on the feedback beam produced by<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1RWmSp-YSU-x-qgdr3WN6ymT3vXmG8eUZvm1RaYDnDsLQxAU6cYBk6FoqIrku3LivR4yOgPY_toIhqZTmo6_o8BRglX0uQHW73j7Bzhhf45z6_cDS0D232X2g3s5CrYuj9bt3hOQWdeR7/s1600/40.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1RWmSp-YSU-x-qgdr3WN6ymT3vXmG8eUZvm1RaYDnDsLQxAU6cYBk6FoqIrku3LivR4yOgPY_toIhqZTmo6_o8BRglX0uQHW73j7Bzhhf45z6_cDS0D232X2g3s5CrYuj9bt3hOQWdeR7/s1600/40.png" /></a>acting on the feedback bellows:<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5GfCxdAol9sE4DXU6U1HNcPLQvDetgANIz0GEdmeIwyr8aGXJrKtbUkxXCocqO-Cn01bW-HkZLlN9ddXTh3fudROnXUJCH2vvkCKJLZrWlAKyOgVcEhYxJYnpD_iQ9Npx5VyymMju2qWk/s1600/41.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5GfCxdAol9sE4DXU6U1HNcPLQvDetgANIz0GEdmeIwyr8aGXJrKtbUkxXCocqO-Cn01bW-HkZLlN9ddXTh3fudROnXUJCH2vvkCKJLZrWlAKyOgVcEhYxJYnpD_iQ9Npx5VyymMju2qWk/s1600/41.png" /></a>(5.41)<br />
<br />
For the condition of balance:<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMDg4sz6ZVKwI2Aeipe3LBiXGo78_8A-zvg5FpPbX8yIrEMW9K85FXxXRSD2EQ2XxDkFw2JHn404-LCWwMUf3KXFzmfIpJ2vLX2hEobLoK_wc2Yvy2tgN59sbADgH0z5Iwy0Kk2VLVNuT9/s1600/42.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMDg4sz6ZVKwI2Aeipe3LBiXGo78_8A-zvg5FpPbX8yIrEMW9K85FXxXRSD2EQ2XxDkFw2JHn404-LCWwMUf3KXFzmfIpJ2vLX2hEobLoK_wc2Yvy2tgN59sbADgH0z5Iwy0Kk2VLVNuT9/s1600/42.png" /></a> (5.42)<br />
or<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwr125hz52JQ5y21vxqCCfbVrNabQWxxh0KhQw4jmnsoV5zxPWIBPL4SA3aoc7d3MThQX685dphksTwOQZ6iy629B6mtm4-pkmh-rfH5m2SGV9sIys3m_lpXhgd3y4_h7bTMCSX1_y-R7A/s1600/43.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwr125hz52JQ5y21vxqCCfbVrNabQWxxh0KhQw4jmnsoV5zxPWIBPL4SA3aoc7d3MThQX685dphksTwOQZ6iy629B6mtm4-pkmh-rfH5m2SGV9sIys3m_lpXhgd3y4_h7bTMCSX1_y-R7A/s1600/43.png" /></a> (5.43)<br />
<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifwVB8BDcm32CnxI-WXsqlV9b-165KiRSU1F92LPchjn_tUwhvIL8J6-zMMTGI0rlIRoUHbbga8WuCep043UQWF-Vrz12zuIuEHbtKpjoKzlDrTAVphRjDKmtP9i4-7sdFc_z6f1KtLVnm/s1600/44.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifwVB8BDcm32CnxI-WXsqlV9b-165KiRSU1F92LPchjn_tUwhvIL8J6-zMMTGI0rlIRoUHbbga8WuCep043UQWF-Vrz12zuIuEHbtKpjoKzlDrTAVphRjDKmtP9i4-7sdFc_z6f1KtLVnm/s400/44.png" width="362" /></a></div>
<div style="text-align: center;">
<i>Figure 5.9. Simplified model of pneumatic differential pressure transmitter</i></div>
<br />
1 - diaphragm capsule; 2 - force beam; 3 - flapper; 4 - nozzle;<br />
5 - span nut; 6 -feedback bellows; 7 - feedback beam;<br />
8 - zero adjustment spring.<br />
<br />
<br />
Since,<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmQsdGZuS0SVaUDLB8uF6SOHmOmUUco0J4y-WUlR5a9_azV0gKlknzXHfMfiiVOSaW3kp8Gfj5mWnkdEtsaL5Pf9fnUwG9X10dAhyuddbtUwvZ_yYUpsDfgAr6tUNqiZAg-2O73POdLVsb/s1600/45.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhmQsdGZuS0SVaUDLB8uF6SOHmOmUUco0J4y-WUlR5a9_azV0gKlknzXHfMfiiVOSaW3kp8Gfj5mWnkdEtsaL5Pf9fnUwG9X10dAhyuddbtUwvZ_yYUpsDfgAr6tUNqiZAg-2O73POdLVsb/s1600/45.png" /></a> (5.44),<br />
then we can get a simplified model for the differential pressure transmitter.<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgekm7WnE6NhDQxSTZyay3rtWRM8jsFtKkLr1eAWSUZfUdQzE5K1u79vtT28pL0OyriI61YbgT1nBFS-y91iBqAIP4DIrzEgCNIsRMryd06wLF3_5aYaZ9oHkhKfep0IdLqQDoovZbgjVjo/s1600/46.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgekm7WnE6NhDQxSTZyay3rtWRM8jsFtKkLr1eAWSUZfUdQzE5K1u79vtT28pL0OyriI61YbgT1nBFS-y91iBqAIP4DIrzEgCNIsRMryd06wLF3_5aYaZ9oHkhKfep0IdLqQDoovZbgjVjo/s1600/46.png" /></a> (5.45)<br />
<span id="goog_533479708"></span><span id="goog_533479709"></span><br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRpYUbHqp_RySyP8Ac2k8N6hWLELPsQxFNWT4AxRbFaAgLhzPxv4ebXaklXEEACBNugxH3v6jfLwPlgLUXT3EmTjxtfiKhU_B2PrUIVrICeyRIWSwakwBGjxsxeNls9BzP3Y6b7fVdSzlB/s1600/47.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRpYUbHqp_RySyP8Ac2k8N6hWLELPsQxFNWT4AxRbFaAgLhzPxv4ebXaklXEEACBNugxH3v6jfLwPlgLUXT3EmTjxtfiKhU_B2PrUIVrICeyRIWSwakwBGjxsxeNls9BzP3Y6b7fVdSzlB/s1600/47.png" /></a>(5.46)<br />
and<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO2CxdmFXX20r8WuuUZ4-NJwKvnGu7CuPQchqLIDDCFa3bmaaUV5txgJKpzUSvVRFJB3E-dofPI7eBIcb4Ku48QS4ZJLQPFR_utylqanO2Ctu3uKk03TCUo-_fnz-xNdPPXd4kZblEaP1N/s1600/48.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO2CxdmFXX20r8WuuUZ4-NJwKvnGu7CuPQchqLIDDCFa3bmaaUV5txgJKpzUSvVRFJB3E-dofPI7eBIcb4Ku48QS4ZJLQPFR_utylqanO2Ctu3uKk03TCUo-_fnz-xNdPPXd4kZblEaP1N/s1600/48.png" /></a>(5.47)<br />
<br />
Adjusting the position of the span nut alters the ratio e/d , and the sensitivity.<br />
<br />
Adjusting the zero spring force F<i>o</i> gives a zero pressure (when P1 = P2 ) of 20 kPa.<br />
<br />
<span style="font-size: large;">A</span><span style="font-size: x-small;"><i>bel</i></span> - the effective area of the feedback bellows, m2;<br />
<span style="font-size: large;">A</span><span style="font-size: x-small;"><i>D</i></span> - effective area of the diaphragm, m2.<br />
<br />
<br /></div>
<div>
<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
</div>
Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-47459781746929304832016-09-16T01:27:00.000+05:302016-09-17T04:13:58.809+05:30Float actuated devices : Level<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">Float actuated devices measure liquid level using a float, which lies on the surface of the liquid and changes its position as the liquid level varies. Fig. 5.1 presents a schematic view of a float-actuated device.</span></span><span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><br /></span></span>
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<div style="text-align: center;">
<i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">Figure 5.1. Schematic diagram of a float-and-cable actuated device.</span></span></i></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><br /></span></span>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">The level of the liquid 1 in the tank 2 is under measurement. A sensitive element 3 (a float of a cylindrical shape) is placed on the surface of this liquid. This sensor is connected through a cable 4 and two rotating wheels 5 with a balancing weight 6. A position of the balancing weight and a pointer 7, attached to it, in respect to a scale 8 determines the level of the liquid in the tank. Density of the float should be less that that of the liquid. Usually, plastic materials are used for manufacturing of floats.</span></span><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuJvNYzyErsP9OXbm2OOI_lfQTXtUQNZeJR_gP88ePF9m90uEtu5z02T6glFXl_x317oGW_mO8tPWuj6sxzjshjLkftnA56UzwPL6rs5VnGHURvaZDBqY0bkweNyKOGq79LJq1Lfk4pLby/s1600/tank-float-level-indicators-250x250.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuJvNYzyErsP9OXbm2OOI_lfQTXtUQNZeJR_gP88ePF9m90uEtu5z02T6glFXl_x317oGW_mO8tPWuj6sxzjshjLkftnA56UzwPL6rs5VnGHURvaZDBqY0bkweNyKOGq79LJq1Lfk4pLby/s200/tank-float-level-indicators-250x250.jpg" width="200" /></a><span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"> </span></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">Application of these devices assumes that the float is immersed in the liquid by the middle of its height. Therefore, when density of the liquid changes an error introduces into results of level measurement. Let’s calculate this error. </span></span><br />
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">The condition of balance for the float may be written in the form:</span></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><br /></span></span>
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<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0SpurY5DR-vffCqHQ9HzEJxjYqQXk7sB5nOVHBeDwxynIwgUYRYnH8qJGficaGOnstygkieLCSyE7rEAcV9l0I_2VhCNRHHw_pFD_yJQQlZvXjq6PXxW7nGL_14xmRCRwG8OkBF_TBDfh/s1600/02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="69" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0SpurY5DR-vffCqHQ9HzEJxjYqQXk7sB5nOVHBeDwxynIwgUYRYnH8qJGficaGOnstygkieLCSyE7rEAcV9l0I_2VhCNRHHw_pFD_yJQQlZvXjq6PXxW7nGL_14xmRCRwG8OkBF_TBDfh/s320/02.png" width="320" /></a></span></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">(5.1)</span></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">where</span></span><br />
<span style="font-size: large;"><span style="font-family: "trebuchet ms" , sans-serif;">F<i><span style="font-size: x-small;">fl</span> = m<span style="font-size: x-small;">fl</span> * </i>g<span style="font-size: x-small;"><i>loc</i></span></span></span><span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><span lang="EN-AU"><span lang="EN-AU"><i><sub><span style="font-size: large;"> </span></sub></i></span></span></span></span><br />
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">- gravitational force acted on the float N, </span></span><br />
<br />
<span style="font-size: small;"><span style="font-family: "trebuchet ms" , sans-serif;"><span lang="EN-AU"><span lang="EN-AU"></span></span></span></span><br />
<div class="separator" style="clear: both; text-align: center;">
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<span style="font-family: "trebuchet ms" , sans-serif;"><i> - resultant force from the balancing weight, cable and friction<br />in the wheels, N ;<br /><span id="goog_347264933"></span><span id="goog_347264934"></span> </i></span><br />
<div class="separator" style="clear: both; text-align: center;">
<i><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhd09BR_s1O5Wfmlx62TygG2NEkXY7aIuKR42VMNfHdcXuvNUspiQ1bQh_2o4fFEc4rvLCjRX4K3faw9dhHlbEZlZ3TgLi4v9cidCg0UzsGmJDlE7go75dqKCzKZnmax9Qm8kby9Nf8dOQD/s1600/03.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="63" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhd09BR_s1O5Wfmlx62TygG2NEkXY7aIuKR42VMNfHdcXuvNUspiQ1bQh_2o4fFEc4rvLCjRX4K3faw9dhHlbEZlZ3TgLi4v9cidCg0UzsGmJDlE7go75dqKCzKZnmax9Qm8kby9Nf8dOQD/s200/03.png" width="200" /></a></i></div>
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><i> - Archimedes’ force acted on the float, N ;</i></span><span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><span style="font-size: large;"><span style="font-family: "trebuchet ms" , sans-serif;"><i> </i></span></span></span></span><br />
<br />
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><span style="font-size: large;"><span style="font-family: "trebuchet ms" , sans-serif;"><i>m<span style="font-size: x-small;">fl</span></i></span></span></span><i><span style="font-size: xx-small;"> </span> - mass of the float, kg ;</i></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><i><br /></i></span><span style="font-family: "trebuchet ms" , sans-serif;"><i><span style="font-size: large;"><span style="font-family: "trebuchet ms" , sans-serif;">g<span style="font-size: x-small;"><i>loc</i></span></span></span><span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"><span lang="EN-AU"><span lang="EN-AU"><i><sub><span style="font-size: large;"> </span></sub></i></span></span></span></span></i><i> - local gravitational acceleration, m/s2 ; </i></span><br />
<div style="text-align: left;">
<span style="font-family: "trebuchet ms" , sans-serif;"><i></i></span><br />
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<span style="font-family: "trebuchet ms" , sans-serif;"><i><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_K_dUyDwgjyV-8NbcKV2BF5z1LjudX5XPc_oksRbFyPbQmABecZibffTclt7i-34HVAeTXDYaab6TAc7GKiwfs9W6X-4HAnFCa4O-GXTYtmsXg5vEIZFbMagd9moKeU06FpzbxhaV3DYZ/s1600/wwwwwwwwwwwwww.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_K_dUyDwgjyV-8NbcKV2BF5z1LjudX5XPc_oksRbFyPbQmABecZibffTclt7i-34HVAeTXDYaab6TAc7GKiwfs9W6X-4HAnFCa4O-GXTYtmsXg5vEIZFbMagd9moKeU06FpzbxhaV3DYZ/s1600/wwwwwwwwwwwwww.png" /></a></i></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><i>
</i></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><i> </i></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><i> - density of the liquid under the float and gas (or vapour) above it,respectively, kg/m3 ;</i></span><br />
<br />
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: large;"><i> </i>S</span><i><span style="font-size: x-small;">fl </span>- horizontal cross-section area of the float, m2; </i></span><br />
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><i><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_2RW0VNaNNk4hZSOA0qoFN2XDJuvEW9ueIfzAHksU7VsyUQHVf8KGk5N0N9P7wgJulgWJcGkZOLlFYvP2Yi9IWnnMYr56llnDFJ0sW6GmgOg-NpBeHKXVPBD-9xI9dR_IeVLTVarDP2la/s1600/04.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_2RW0VNaNNk4hZSOA0qoFN2XDJuvEW9ueIfzAHksU7VsyUQHVf8KGk5N0N9P7wgJulgWJcGkZOLlFYvP2Yi9IWnnMYr56llnDFJ0sW6GmgOg-NpBeHKXVPBD-9xI9dR_IeVLTVarDP2la/s1600/04.png" /></a></i></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><i> </i></span><span style="font-family: "trebuchet ms" , sans-serif;"><i> - heights of the float parts in the liquid and in the gas (or vapour)<br />above it, respectively,</i></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><i><br /><br />Equation (5.1) can be re-written as follows:</i></span><br />
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvuwy7xO2uo9EketMBCnhN6PIJKeuMvlknw0oZ4EwkM6kOSSdcWud5XAnWnGaxLqadlzCmLt_GA_p7XS-pWvIbchJEMqRVLcDdMgZjfwZYsFCakgmN3PzMqyg1ecirruacvJUa1cCtePiw/s1600/05.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="47" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvuwy7xO2uo9EketMBCnhN6PIJKeuMvlknw0oZ4EwkM6kOSSdcWud5XAnWnGaxLqadlzCmLt_GA_p7XS-pWvIbchJEMqRVLcDdMgZjfwZYsFCakgmN3PzMqyg1ecirruacvJUa1cCtePiw/s400/05.png" width="400" /></a><i>(5.2)<br /><br />Let for the unchanged level the density of the liquid has increased by the value of </i><i><!--[if gte mso 9]><xml>
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<![endif]--><span style="font-family: "trebuchet ms" , sans-serif;">Δρ<i> liq . Then, the depth of immersion of the float into the liquid and gas (or vapour) will change by the value of </i><i><br /> </i></span><br />
<div class="MsoNormal" style="text-align: justify;">
<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSV36DizqVL_disoDqVgLLe9KIO4G8zoaMR5IWtlVn-zeFJfkUljepfh13aGI8B3QmtS0N_84UFkNEh0NgqhUoNpok8GLedgycnLdWFgZ5pGx_TzvLQuMN4eC6Bp8x1EGgJ5uBdOiRmhah/s1600/eeee.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSV36DizqVL_disoDqVgLLe9KIO4G8zoaMR5IWtlVn-zeFJfkUljepfh13aGI8B3QmtS0N_84UFkNEh0NgqhUoNpok8GLedgycnLdWFgZ5pGx_TzvLQuMN4eC6Bp8x1EGgJ5uBdOiRmhah/s1600/eeee.png" /></a><i> </i></span></div>
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<br /></div>
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<br /></div>
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<span style="font-size: small;"><span style="font-family: "trebuchet ms" , sans-serif;"><i>, where the sign “+” stands for the immersion of the
float into the gas (or vapour) and the sign “-“ stands for the
immersion of the float into the liquid. </i></span></span></div>
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<br /></div>
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<span style="font-size: small;"><span style="font-family: "trebuchet ms" , sans-serif;"><i>Taking into account that </i></span></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxUoO0aPitWdx94kGJRygreTOVWOP5Lj-3wmQfHaOOzv_WcN5wpq6GLlMIXdg73KmPBEN2NfJ2aDt-i_eh5vnktVvNNpqGqgftyuw7ObwgYSR2d8zRPaeqo6j1zL-aq3DQN01OsE9M5MlB/s1600/07.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="51" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxUoO0aPitWdx94kGJRygreTOVWOP5Lj-3wmQfHaOOzv_WcN5wpq6GLlMIXdg73KmPBEN2NfJ2aDt-i_eh5vnktVvNNpqGqgftyuw7ObwgYSR2d8zRPaeqo6j1zL-aq3DQN01OsE9M5MlB/s200/07.png" width="200" /></a><span style="font-family: "trebuchet ms" , sans-serif;"><i> </i></span></div>
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<br /></div>
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<span style="font-family: "trebuchet ms" , sans-serif;"></span><span style="font-family: "trebuchet ms" , sans-serif;"></span><span style="font-size: small;"><span style="font-family: "trebuchet ms" , sans-serif;"><i>does
not change considerably.</i></span></span></div>
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<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxkWxgHffGisY_DcNO-56Gy15mnFp1YRK0YhmdNSqjSLJwzTbSnUyA4PwBDRfTUZDlilRTpKFIbbhV5pSOH1GAaFPf1dOXoUPeXnH1HmxgmWbGDMEUy0lxBXBA3C21lxsIzpB9_lG3lv_r/s1600/08.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="104" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxkWxgHffGisY_DcNO-56Gy15mnFp1YRK0YhmdNSqjSLJwzTbSnUyA4PwBDRfTUZDlilRTpKFIbbhV5pSOH1GAaFPf1dOXoUPeXnH1HmxgmWbGDMEUy0lxBXBA3C21lxsIzpB9_lG3lv_r/s640/08.png" width="640" /></a></span></div>
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<br /></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="font-size: small;"><span style="font-family: "trebuchet ms" , sans-serif;"><i>We can re-write equation (5.2) as follows:</i></span></span></div>
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<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZ5Df_J6t5GnXqumm-GzC2q6zWQRqqyzKaAhKtceznvceANX6-oLXJGq_MJ1rTh_8pijNbdBlG7td4mAYqEpmnfgV_Sf8qXS94rJLDj7o2i9mE3ChfyLdke9sEUEgaurw-E2JBJVUXh0ef/s1600/09.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="32" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZ5Df_J6t5GnXqumm-GzC2q6zWQRqqyzKaAhKtceznvceANX6-oLXJGq_MJ1rTh_8pijNbdBlG7td4mAYqEpmnfgV_Sf8qXS94rJLDj7o2i9mE3ChfyLdke9sEUEgaurw-E2JBJVUXh0ef/s400/09.png" width="400" /></a></span></div>
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">(5.3) </span></span></div>
<div class="separator" style="clear: both; text-align: left;">
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">Let </span></span></div>
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6Kq4SR8wjlY4vjTfq23QyJfy0RTWqwRjefhidCj9TpJGPWHS36gHA-807w0vTbmgI2VzCMnVd0-8m3iRD27S8KlpsLT1TJ0vV2kPX3WvrOGU-CTI-DIC1ZsNsNVtpYANUMDnSKgvmqbmb/s1600/10.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="43" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6Kq4SR8wjlY4vjTfq23QyJfy0RTWqwRjefhidCj9TpJGPWHS36gHA-807w0vTbmgI2VzCMnVd0-8m3iRD27S8KlpsLT1TJ0vV2kPX3WvrOGU-CTI-DIC1ZsNsNVtpYANUMDnSKgvmqbmb/s200/10.png" width="200" /></a></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">Then,</span></span><br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWFZYyGJ_6wlE9Id9g0r0J_TPNukokU117JfU0-aQkDCmDaYRFSYmT547bMRTPZScFRCQcCSjdBlknUq5Q2u5B2dzBSlxNb6jzJ-kG3nB2DlhPKkkEbdh0yt2hCgaFIkmCAyEcGaIm0rCx/s1600/11.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="65" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWFZYyGJ_6wlE9Id9g0r0J_TPNukokU117JfU0-aQkDCmDaYRFSYmT547bMRTPZScFRCQcCSjdBlknUq5Q2u5B2dzBSlxNb6jzJ-kG3nB2DlhPKkkEbdh0yt2hCgaFIkmCAyEcGaIm0rCx/s400/11.png" width="400" /> </a></span></div>
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">(5.4) </span></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"> Neglect the variation of the Archimedes’ force acting from gas on the float, or</span></span><br />
<div class="separator" style="clear: both; text-align: center;">
<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHPX_USelUz2GRv6hGnCk7xjHyGeptZnh6rMKpLVMJs8MABKxvvaG0UdrlM6IhQgWsZDEl5nbvsag3A9avH0Be60jjNkAreO7t9CxK8a01r_TCst3DuVAfeTWjKv6aZreTukEh8zzUGdGw/s1600/12.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="55" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHPX_USelUz2GRv6hGnCk7xjHyGeptZnh6rMKpLVMJs8MABKxvvaG0UdrlM6IhQgWsZDEl5nbvsag3A9avH0Be60jjNkAreO7t9CxK8a01r_TCst3DuVAfeTWjKv6aZreTukEh8zzUGdGw/s320/12.png" width="320" /></a></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">(5.5)</span></span><br />
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">Now we get :</span></span><br />
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<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvgemrbLCuaP708h1dwY23F-b1EBAC0Rn1OdR_pfqjbqSWXZ_kEY6w0MaQnoQxxLsc0UJQTKEHahfGoWr3-eUKLIgPERKbroaR9npdFtIlI1Fin15XEESaYXH_XYlE3mUKq9dzte7iLKU9/s1600/13.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="47" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvgemrbLCuaP708h1dwY23F-b1EBAC0Rn1OdR_pfqjbqSWXZ_kEY6w0MaQnoQxxLsc0UJQTKEHahfGoWr3-eUKLIgPERKbroaR9npdFtIlI1Fin15XEESaYXH_XYlE3mUKq9dzte7iLKU9/s320/13.png" width="320" /></a></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">(5.6)</span></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"> or </span></span><br />
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<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicgOH00qnl4HY7rD_BD8SC3mpWgckeGOEYCq6qAhFvzeAT9VNFZ7YVPprv5cqldBJW6N1Sfdh8w8oK6ekNW5EQY5nNMPhHxJuhBLWGY4NDZJhQSCW8IsOurInUX4c82y3aVPoWfsbqLt3w/s1600/14.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="60" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicgOH00qnl4HY7rD_BD8SC3mpWgckeGOEYCq6qAhFvzeAT9VNFZ7YVPprv5cqldBJW6N1Sfdh8w8oK6ekNW5EQY5nNMPhHxJuhBLWGY4NDZJhQSCW8IsOurInUX4c82y3aVPoWfsbqLt3w/s320/14.png" width="320" /></a></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;"> (5.7)</span></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">Finally, we get an error due to change in liquid density:</span></span><br />
<br />
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<span style="font-family: "trebuchet ms" , sans-serif;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8QzbvnSWtdcOir4gwp0EUwWOUXd4ZlRsrG66N4TM1SpeJTh0hyphenhyphen0KH-L2vlgRYAsNMCWA6QXX5w-BvVyOkNuL7cc6Au_iWPVWIf2fcKSz2u1TwiD7E8tyLBUX1MZzuzTLafZSGcdNS-bxT/s1600/15.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="67" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8QzbvnSWtdcOir4gwp0EUwWOUXd4ZlRsrG66N4TM1SpeJTh0hyphenhyphen0KH-L2vlgRYAsNMCWA6QXX5w-BvVyOkNuL7cc6Au_iWPVWIf2fcKSz2u1TwiD7E8tyLBUX1MZzuzTLafZSGcdNS-bxT/s200/15.png" width="200" /></a></span></div>
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">(5.8)</span></span><br />
<br />
<span style="font-family: "trebuchet ms" , sans-serif;"><span style="font-size: small;">These devices have a simple design, high accuracy, wide range of measuring levels and the possibility of level measurement for aggressive and viscous liquids. However, they are not able to measure levels in tanks under pressure. </span></span><br />
<br />
<br />
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<span style="font-family: "trebuchet ms" , sans-serif;"><br /></span></div>
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<span style="font-size: xx-small;"><i><span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></i></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-89631842001200217382013-12-21T19:10:00.002+05:302016-09-17T03:34:57.760+05:30Instrumentation for level measurements<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0-MP2bnzYv5PyoawhGZu-cwB4E2omLBN9Q3drb0msQiEuubMyex0m4DnFSUQUxtiiz1P3dniQWn9Bx1jg7gq4yxDd5gU5P2OS9BnLlYD-_Sc8-6tTmgGoEND6v156CH9qOwIMZVf3JrCE/s1600/level-instruments-250x250.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><span style="font-family: "trebuchet ms" , sans-serif;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0-MP2bnzYv5PyoawhGZu-cwB4E2omLBN9Q3drb0msQiEuubMyex0m4DnFSUQUxtiiz1P3dniQWn9Bx1jg7gq4yxDd5gU5P2OS9BnLlYD-_Sc8-6tTmgGoEND6v156CH9qOwIMZVf3JrCE/s1600/level-instruments-250x250.jpg" /></span></a></div>
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<span style="font-family: "trebuchet ms" , sans-serif;">An accurate level measurement is crucial for the evaluation of the quantity of materials, phase boundaries, etc. in storage and processing vessels (tanks, wells, reservoirs, columns, etc.). This apparatus may operate under high pressure, under vacuum or at atmospheric pressure at various temperatures. Substances may be as follows: liquids, vapours, gases, solids and their combination. These substances may be corrosive and aggressive. All the above mentioned creates difficulties for level measurement in industrial environment. In the upcoming posts several widely used instruments will be explained :</span><br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIp4uM-Qr4a3UTyJIL2l_HXbeu8aOvGe3Z8F1MrrTDFgtVl4lSVntm92vyWbvOz-WDTf5EWiazCwMrbdyjvqeWvRLA-h9VNQ3nnUZLyY1BAPS-sZRii55PZ736_kbGtonup_-ftc9zELDk/s1600/Level_en.gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><span style="font-family: "trebuchet ms" , sans-serif;"><img border="0" height="236" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIp4uM-Qr4a3UTyJIL2l_HXbeu8aOvGe3Z8F1MrrTDFgtVl4lSVntm92vyWbvOz-WDTf5EWiazCwMrbdyjvqeWvRLA-h9VNQ3nnUZLyY1BAPS-sZRii55PZ736_kbGtonup_-ftc9zELDk/s400/Level_en.gif" width="400" /></span></a><span style="font-family: "trebuchet ms" , sans-serif;"><br /></span><br />
<span style="font-family: "trebuchet ms" , sans-serif;"> <a href="http://aboutinstrumentation.blogspot.com/2016/09/float-actuated-devices.html" target="_blank">1) Float actuated devices</a></span><br />
<a href="http://aboutinstrumentation.blogspot.com/2016/09/displacer-buoyancy-devices.html" target="_blank"><span style="font-family: "trebuchet ms" , sans-serif;">2) Displacer (buoyancy) devices</span></a><br />
<a href="http://aboutinstrumentation.blogspot.com/2016/09/liquid-head-pressure-devices.html" target="_blank"><span style="font-family: "trebuchet ms" , sans-serif;">3) Liquid head pressure devices</span></a><br />
<a href="http://aboutinstrumentation.blogspot.com/2016/09/capacitance-devices.html" target="_blank"><span style="font-family: "trebuchet ms" , sans-serif;">4) Capacitance devices</span></a><br />
<a href="http://aboutinstrumentation.blogspot.com/2016/09/conductance-devices.html" target="_blank"><span style="font-family: "trebuchet ms" , sans-serif;">5) Conductance devices</span></a><br />
<a href="http://aboutinstrumentation.blogspot.com/2016/09/ultrasonic-devices-level.html" target="_blank"><span style="font-family: "trebuchet ms" , sans-serif;">6) Ultrasonic devices</span></a><br />
<a href="http://aboutinstrumentation.blogspot.com/2016/09/nucleonic-devices-level.html" target="_blank"><span style="font-family: "trebuchet ms" , sans-serif;">7) Nucleonic devices</span></a><br />
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<span style="font-family: "trebuchet ms" , sans-serif;"><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Article Source:: </span><span style="background-color: white; color: #4c4c4c; line-height: 20px; margin: 0px; padding: 0px; text-align: justify;">Dr. Alexander Badalyan, University of South Australia</span></span></div>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0tag:blogger.com,1999:blog-4918615211605852720.post-60195603500617156432013-05-22T18:38:00.000+05:302013-05-22T18:55:29.291+05:30Instrumentation for Temperature Measurement<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja9esaZ-tpT-PJ9mDZ7E3jWVAnqDk3_WgLokN_hKWCqLULJ9fSHt27vAxKHo8qUpm0xF1gllCfQJc6cFmUTq3sTKxJIwlXx_wB0TSGz-Aix3degeVuYn2S0sW_LW6sFnInJlKBg_7I9A_p/s1600/Temperature.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><span style="font-family: Verdana, sans-serif;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja9esaZ-tpT-PJ9mDZ7E3jWVAnqDk3_WgLokN_hKWCqLULJ9fSHt27vAxKHo8qUpm0xF1gllCfQJc6cFmUTq3sTKxJIwlXx_wB0TSGz-Aix3degeVuYn2S0sW_LW6sFnInJlKBg_7I9A_p/s200/Temperature.jpg" style="cursor: move;" width="150" /></span></a></div>
<span style="font-family: Verdana, sans-serif;"><span style="background-color: white; line-height: 19.1875px;">Temperature</span><span style="background-color: white; line-height: 19.1875px;"> is a physical quantity that is a measure of hotness and coldness on a numerical scale.</span><span style="background-color: white; line-height: 19.1875px;"> It is a measure of the </span>thermal energy<span style="background-color: white; line-height: 19.1875px;"> per particle of matter or radiation; it is measured by a </span>thermometer<span style="background-color: white; line-height: 19.1875px;">, which may be </span>calibrated<span style="background-color: white; line-height: 19.1875px;"> in any of various </span>temperature scales<span style="background-color: white; line-height: 19.1875px;">, Celsius, Fahrenheit, Kelvin, etc.</span></span><br />
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<span style="font-family: Verdana, sans-serif;"><span style="background-color: white; line-height: 19.1875px;">In </span>kinetic theory<span style="background-color: white; line-height: 19.1875px;"> and in </span>statistical mechanics<span style="background-color: white; line-height: 19.1875px;">, temperature is the effect of the </span>thermal energy<span style="background-color: white; line-height: 19.1875px;"> arising from the motion of microscopic particles</span><span style="background-color: white; line-height: 19.1875px;"> such as atoms, molecules and photons.</span></span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3uE-5qpiR_Ytz44mHz_16c46GIxA-bBZGiSy84e3BLu2jaGRZxJcjtt_VZP5mSocykrCqgMapzpS-qJtNIcuS5OemH1SW33_QcYYc03WTzGNKEufySsE0loL1w4BsVc6v4Oyzl-g6ZWMg/s1600/temptr.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: Verdana, sans-serif;"><img border="0" height="250" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3uE-5qpiR_Ytz44mHz_16c46GIxA-bBZGiSy84e3BLu2jaGRZxJcjtt_VZP5mSocykrCqgMapzpS-qJtNIcuS5OemH1SW33_QcYYc03WTzGNKEufySsE0loL1w4BsVc6v4Oyzl-g6ZWMg/s400/temptr.gif" width="400" /></span></a></div>
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<span style="background-color: white; line-height: 19.1875px;"><span style="font-family: Verdana, sans-serif;">In the post '<a href="http://aboutinstrumentation.blogspot.com/2011/12/temperature-basics.html" target="_blank">Temperature : Basics</a>' explains all the basic details related to Temperature. The links below will explain the instrumentation for temperature measurements:</span></span><br />
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<li><span style="line-height: 19.1875px;"><a href="http://aboutinstrumentation.blogspot.com/2012/07/temperature-scales-and-units.html" target="_blank"><span style="font-family: Verdana, sans-serif;">Temperature scales, temperature units</span></a></span></li>
<li><span style="line-height: 19.1875px;"><a href="http://aboutinstrumentation.blogspot.com/2012/07/liquid-in-glass-thermometers.html" target="_blank"><span style="font-family: Verdana, sans-serif;">Liquid-in-glass thermometers</span></a></span></li>
<li><span style="line-height: 19.1875px;"><a href="http://aboutinstrumentation.blogspot.com/2012/07/filled-thermal-systems.html" target="_blank"><span style="font-family: Verdana, sans-serif;">Filled thermal systems</span></a></span></li>
<li><span style="line-height: 19.1875px;"><a href="http://aboutinstrumentation.blogspot.com/2012/07/thermocouples-basics.html" target="_blank"><span style="font-family: Verdana, sans-serif;">Thermocouples</span></a></span></li>
<li><span style="line-height: 19.1875px;"><a href="http://aboutinstrumentation.blogspot.com/2012/08/resistance-temperature-detectors-basics.html" target="_blank"><span style="font-family: Verdana, sans-serif;">Resistance temperature detectors</span></a></span></li>
<li><span style="line-height: 19.1875px;"><a href="http://aboutinstrumentation.blogspot.com/2012/09/thermistors-basics.html" target="_blank"><span style="font-family: Verdana, sans-serif;">Thermistors</span></a></span></li>
<li><span style="line-height: 19.1875px;"><a href="http://aboutinstrumentation.blogspot.com/2012/09/optical-and-radiation-pyrometers.html" target="_blank"><span style="font-family: Verdana, sans-serif;">Optical and radiation pyrometers</span></a></span></li>
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Sijo Joyhttp://www.blogger.com/profile/04533117692631859506noreply@blogger.com0