Calculate Flow Transmitter Output Current

A  flow transmitter ranges from 0 to 350 GPM with 4 to 20 mA output, direct-responding. Calculate the current signal value at a flow rate  of 204 GPM.

Flow Transmitter

We are solving this problem using the standard 4-20mA Conversion Formula. Click here for the formula

One way we could solve for the amount of signal current is to convert the flow value of 204.

GPM  into a ratio of the flowmeter’s full-flow value,  then apply the same formula we used in the previous example relating percentage to milliamps.

Converting the flow rate into a “per unit” ratio is a matter of simple division since the flow measurement range is zero-based:

Therefore,  the transmitter should output a PV signal of 13.3 mA at a flow rate of 204 GPM.

Flow Transmitter Calculations

An alternative approach is to set up a linear equation specifically for this flowmeter given its measurement range (0 to 350 GPM)  and output signal range (4 to 20 mA).

We will begin this process by sketching  a simple graph relating flow rate to current:

Therefore,  the transmitter should output a PV signal of 13.3 mA at a flow rate of 204 GPM.

We can also solve the problem using a direct formula. Click here for the formula

If you liked this article, then please subscribe to our YouTube Channel for Instrumentation, Electrical, PLC, and SCADA video tutorials.

You can also follow us on Facebook and Twitter to receive daily updates.

Read Next:

• Flow Control Loop Controller
• Variable Area Flow Meters
• Linear to Square Root Extraction
• PV to Percentage Conversion
• Closed Tank Level Calculations