How to Use the Flowmeter K-Factor Calculator
Turbine and paddlewheel meters report flow as pulses rather than as a current signal. The K-factor states how many pulses come out for each unit of volume, so counting pulses is all it takes to recover both volume and flow rate.
The arithmetic is direct: volume is pulses ÷ K-factor and flow is frequency (Hz) × 60 ÷ K-factor. With a 100 pulses per gallon meter counting 1,000 pulses in 60 seconds, the output runs at 16.67 Hz, flow is 10 GPM and 10 gallons passed through. Volume per pulse is simply the inverse of the K-factor, 0.01 gallon here, and that figure is also the finest resolution the totalizer can ever show.
The frequency at maximum flow is the number to check before choosing a PLC high speed counter or a flow transmitter. If it exceeds what the input card can follow, pulses are dropped and the reading comes out low. At the other end, very low flow produces so few pulses that the update rate suffers and a longer counting window is needed. K-factor also shifts with fluid viscosity and piping, so for custody grade measurement use the value on the calibration certificate.
Frequently Asked Questions
It is printed on the meter nameplate or the calibration certificate as pulses per gallon or pulses per liter. Individual meters of the same model differ slightly, so the measured value on that specific unit is the accurate one.
Pulses are whole numbers, so volume only registers once each pulse completes, and meter linearity degrades at low flow. A fluid whose viscosity differs from the calibration condition also shifts the effective K-factor.
Yes, and a longer window averages out noise, which suits totalizing. It does slow down the response, so keep the counting window short whenever the number is used for live flow monitoring or control.