We have an oxygen meter that is pressure and temperature compensated. My question is: if the flow meter is calibrated to standard conditions (60 degf and 14.7 psig), then when pressure and temp compensating what values are used as the design pressure and temperature?

Here is our formula compensated flow = F* sqrt(((p+po/rp))*(rt/(t+to)*(rg/g))

F = uncompensated flow
COMPTERM = sqrt(((p+po/rp))*(rt/(t+to)*(rg/g))
P = GUAGE PRESS
rp = DESING PRESS
rt = design temp
to = convert to absolute temp
po = convert press to absolute

 

To compensate a differential flow device, for a gas, using temperature and pressure, you have it correct except for rg/g. I'm assuming they are design and flowing DP and they need to be flipped (g/rg). This is a simplified approach utilizing the ideal gas law, as compared to actually calculating the flowing density using another method, like Van der Waals (which is seldom required).

 

Since you use sqrt, I am assuming you use orifice (or other dp sensor) as Flow element. design pressure and temperature refer to pressure and temperature used when you are sizing the orifice.