Actual & Standard Flow


Thread Starter



when flow transmitter send a 4-20 mA signal of a range of0-1000 SCMH , How to control the flow if the setpoint in actual terms, Do I have to compensate the flow and if so Could anyone please help me with these equations in metric format .


Bruce Durdle

If the transmitter is in fact sending a signal proportional to the standardised flow, you can convert to actual flow by multiplying by (standardised pressure base in kPaA/actual pressure in kPaA) x (actual temperature in K/standardised temperature base in K).

However, first check that you cannot get the actual flow out of your flow transmitter - most measurements will have to be compensated inside the transmitter to give standardised values. Note also that in this calculation you need to use absolute values for pressure and temperature rather than gauge pressure and °C or °F.