# Differential Pressure Flow Rate Formula

I’m just asking to see if anybody can maybe point me to someone who I could ask questions about how to calculate flow rate of a GAS with differential pressure.

These are the only variables that I have to work with.

High Pressure (P1) in Psi
Low Pressure (P2) in Psi
Temperature
Orifice Dia.
Pipe Dia.
Specific Gravity.

Thanks for any help.

You’re looking for Bernoulli’s principle, with either assumptions made about the compressibility of your flow (isobaric/isochoric conditions), or use a suitable equation of state to solve for compressibility (Redlich-Kwong, Peng-Robinson, etc.). It’d probably be more cost effective to just buy a proper flow computer than to take the time to try and implement this yourself.

https://www.yokogawa.com/us/solutions/products-platforms/field-instruments/flow-meters/dp-flow/differential-pressure-flow-tertiary-elements/415-steam-and-gas/

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Thanks for the reply, but that’s not an option. I’m taking over another project and I just need to be able calculate the flow rate with the variables I mentioned.

I 2nd the previous poster, buy the right tool for the job. If you are dead set against using one then you need to research the aga3 flow calculation equation at a minimum, and you will need more info than you provided.

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This type of calculation, which is trivial for liquids, is a whole different ballgame for compressible flow.

I’ve never heard of these folks, but they’re offing a gas flow library in Python which you could possibly integrate into Ignition.

Unless you’ve got a masters degree in fluids/thermodynamics you’re not going to be able to roll your own gas flow calculations with any degree of accuracy.

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Thanks again, I will dive deeper into this matter! I do appreciate the feedback.

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