Key Instruments: Flowmeter Manufacturing Technical Support

These tables and examples are for correcting a flowmeter given the correct flowrate ONLY if you are using a flowmeter outside of its designed parameter (ie, using a meter at anything other than STP - Standard Temperature and Pressure).

Pressure Effects
• Elevated pressures (above atmosphere)
allow for greater capacity for a
given flowmeter

• To determine the actual flowrate (at the elevated
pressure), the following formula is used:

Actual Flow Rate for Flowmeters

• All pressures are in absolute, not gauge

Temperature Effects
• Elevated temperatures (above standard atmospheric
temperature) decrease maximum flowrate for a given
flow body

• To determine the actual flowrate, the following
formula is used:

Actual Flow Rate for Flowmeter

• All temperatures are in absolute

Pressure Correction Example
• Our flowmeters are calibrated at a standard pressure
  of 14.696 PSIA (which is equivalent to 0 PSIG)

• If a customer is operating the meter at 20 PSIG,
what will the effect be on the flow reading?
       – The actual flowrate will be higher than that
          indicated by the flowmeter
       – How much higher will it be?

Pressure Correction Example

Temperature Correction Example
• Our flowmeters are calibrated at a standard temperature
of 20 °C or 68 °F

• If a customer is using the meter at 30 °C, what will the
effect be on the flow reading?
       – The actual flowrate will be lower than that indicated
          by the flowmeter
       – How much lower will it be?

Temperature Correction Example

Pressure Correction Example

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