Flow Measurement · Free Calculator
Flow Meter Factor and K Factor Correction Calculator
After proving a flowmeter against a reference (prover, master meter or weigh tank), find the meter factor, the error and the corrected K factor for the transmitter or flow computer.
Meter factorProverK factorCustody transfer
L
L
pulses/L
Meter factor MF0.99681
Meter error+0.32 %
Corrected K factor125.801 pulses/L
Pulses counted125,801
How this result was calculated
- MF = Vreference ÷ Vmeter = 1,000 ÷ 1,003.2 = 0.99681
- Corrected K = K ÷ MF = pulses ÷ Vreference = 125.801
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Meter Factor Formulas
MF = Vreference ÷ Vindicated
Knew = Kold ÷ MF = pulses ÷ Vreference
Error = (Vindicated − Vreference) ÷ Vreference
Knew = Kold ÷ MF = pulses ÷ Vreference
Error = (Vindicated − Vreference) ÷ Vreference
Volumes must be at the same conditions (corrected for temperature and pressure where required). A meter factor is either applied in the flow computer (corrected volume = indicated × MF) or used to correct the K factor, not both.
Worked example
A meter reads 1003.2 L against a 1000.0 L prover volume: MF = 0.99681, error +0.32 %. With K = 125.4 pulses/L, the corrected K factor is 125.80 pulses/L.
Key insight: repeat proving runs and use the average meter factor; the spread of the runs shows the meter repeatability, which custody transfer standards limit.
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Frequently Asked Questions
What is a meter factor?
The ratio of the true (reference) quantity to the quantity the meter indicated during proving.
Should I change the K factor or apply a meter factor?
Either, depending on the system, but never both. Flow computers usually apply MF; simpler transmitters need a corrected K factor.
How many proving runs are needed?
Custody transfer practice typically uses several consecutive runs that must agree within a set repeatability, often 0.05 %.
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