Symbols for instrumentation layouts
First Letter | Succeeding Letters | ||||
Measured or initiating variable | Modifier | Readout or passive function | Output function | Modifier | |
A | Analysis | Alarm | |||
B | Burner flame | User’s choice | User’s choice | User’s choice | |
C | Conductivity (electrical) | Control | |||
D | Density (mass), specific gravity | Differential | |||
E | Voltage (e.m.f.) | Primary element | |||
F | Flow rate | Ratio (fraction) | |||
G | Gaging (dimensional) | Glass | |||
H | Hand (manually initiated) | High | |||
I | Current (electrical) | Indicate | |||
J | Power | Scan | |||
K | Time or time schedule | Control station | |||
L | Level | Light | low | ||
M | Moisture or humidity | Middle or intermediate | |||
N | User’s choice | User’s choice | User’s choice | User’s choice | |
O | User’s choice | Orifice (restriction | |||
P | Pressure or vacuum | Point (test connection) | |||
Q | Quantity or event | Integrate or totalise | |||
R | Radioactivity | Record or print | |||
S | Speed or frequency | Safety | Switch | ||
T | Temperature | Transmit | |||
U | Multivariable | Multifunction | Multifunction | Multifunction | |
V | Viscosity | Valve, damper | |||
W | Weight or force | ||||
X | Unclassified | Unclassified | Unclassified | Unclassified | |
Y | User’s choice | Relay or compute | |||
Z | Position | Drive, actuate |
Article Source:: Dr. Alexander Badalyan, University of South Australia