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

Flow Transmitter Calculations

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:

Flow Transmitter 4-20 mA formula

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:

flow transmitter formula

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

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2 thoughts on “Calculate Flow Transmitter Output Current”

  1. Also Another Simple way to calculate:
    Signal = 4 – 20 mA..
    So Signal varies between 16 mA
    So Each gallon tends to have (16/350)= 0.046 mA
    So 204 Gallon will make (0.0457 * 204) = 9.33 mA
    Hence Output signal will be 4 mA + 9.33 mA = 13.33 mA

    Reply
  2. how calibrate a ff type flow transmitter ABB 2600T range is 53.39mbar and out showing 5000m3/H how calculate plz gv reply on transmitter showing 53.39 m baar and on data sheet showing calibration range 5000 m3/hm confuse

    Reply

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