A flow transmitter is ranged 0 to 350 GPM, 4-20 mA output, direct-responding. Calculate the current signal value at a flow rate of 204 GPM.
We are solving this problem using standard 4-20mA conversion Formula. Click here for 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.
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