Different flow meters and their principles of working

The most common principals for fluid flow metering are:

•    Differential Pressure Flowmeters
•    Velocity Flowmeters
•    Positive Displacement Flowmeters
•    Mass Flowmeters
•    Open Channel Flowmeters

Differential Pressure Flowmeters : 

In a differential pressure drop device the flow is calculated by measuring the pressure drop over an obstructions inserted in the flow. The differential pressure flowmeter is based on the Bernoullis Equation.

Velocity Flowmeters : 

In a velocity flowmeter the flow is calculated by measuring the speed in one or more points in the flow, and integrating the flow speed over the flow area.

Positive Displacement Flowmeters :
The positive displacement flowmeter measures process fluid flow by precision-fitted rotors as flow measuring elements. Known and fixed volumes are displaced between the rotors. The rotation of the rotors are proportional to the volume of the fluid being displaced.

Mass Flowmeters :
Mass meters measure the mass flow rate directly.

Open Channel Flowmeters :
A common method of measuring flow through an open channel is to measure the height of the liquid as it passes over an obstruction as a flume or weir in the channel.

In the upcoming posts the detailed explanation of different flowmeters that uses the mentioned principles is covered. See those.

Article Source : www.engineeringtoolbox.com