Pressure / Temperature corrections

[progasltd]

I'm trying to determine the source and accuracy of two corrections applied for natural gas metering systems. These are used to correct for pressure and temperature effects - in my application for an ultrasonic meter stream.

I believe these may originate from API Manual Petroleum Measurement Standards (MPMS) although unsure of relevant chapters.

I'd be grateful for confirmation of accuracy and equally specification of the relevant documentation required to be obtained from API (or others)

CTSM = 1+3{LinMeter(Tl - Tcal)}
where LinMeter = linear temp expansion coefficient of spool
Tl = live meter temperature
Tcal = Spool calibration temperature

CPSM = 1+3{strain(Pl+Pcal)}
where strain = pressure expansion coefficient for the spool body
Pl = live spool (meter) pressure
Pcal = spool calibration pressure

regards
Neil