# Calculating Flow from Pulse Flow Meter

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#### Abdel Nasser Marwat

Here is the brief description of how Flow can be calculated from the Pulse flow meter in the PLC Code and what fancy things we can do to the analog value of Flow in our PLC Code.

The pulse flow meter generates the digital pulses in the form of 1 and 0s when measuring the flow. The more is the flow, the faster would be the pulses generated. The pulses come to the digital Input card of the PLC as a DI Signal. In the PLC code, the pulses are added for specific time and there are 20 pulses from flow meter in 5 sec then it means that there are 4 pulses in a sec.

We have to find from the specification of the Flow meter that how much flow is equal to one pulse. Let it is 5 Liters/sec in 1 pulse then our flow is (5 Lit/sec)x(4 Pulses) and our flow would be 20 Lit/sec. Once we have the flow you can do all fancy things to the flow to calculate flow in m3/sec etc etc. By the way, we divide flow in L/sec by 1000 to get flow in m3/sec.

The volume of liquid flowing can also be calculated by adding the flow for certain pulses and then dividing that total number by number of pulses. You can have HIHI, HI, LO and LOLO alarms generated from the analog flow value once we have some setpoints for HIHI, HI, LO and LOLO. The alarms can be generated by comparing the flow to alarm setpoints and the alarms can be shown on HMI, if we have one in our SCADA system.