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Relationship between GPM(Liquid) and SCFH(gases)

2010-11-30

A product catalog details a table of liquid flow rates GPM's and gas flow rates in SCFH's for excess flow check valves. Is a relationship available that relates GPM and SCFH for different liquified products?

You could derive such a table, but it's not as straightforward as your question - as worded - appears to be hoping.  These things depend on densities, viscosities, coefficients of discharge, compressibility, and a host of other component-specific data.  Good resources would be a Control Valve Handbook and Crane Technical Paper 410 / 410M.  With those two references, you could derive relations that get you in the ball park.

I assume you are not concerned with flow undergoing a phase change through the component.  It would get much more involved for multiphase or flashing flow.Crude oil and refined products are always custody transferred at a standard defined by the custody transfer contract.  Great pains are taken to ensure accuracy by calibrating the flowmeters by running a prover loops at the beginning of every shift, significant change in pressure or temperature, significant change in ambient temperature and on every change of product.

No.  You cannot do this.  SCF is a statement of the imaginary volume of gas at an arbitrary set of standard conditions--the term SCF is not defined for any liquid products.  If you want to develop a gpm to ft^3/hr graph for a given liquid, it is easy and linear.

To develop a gas capacity of a check valve, you have to be working in mass flow terms or in volumes at actual conditions, not "standard" mythology.  I can get a LOT more SCF's of Helium through a check valve in an hour at 1,000 psig than I can get of CO2 at 0 psig.  The capacity of the valve is a function of things like fluid velocity, acceptable dP, fluid properties, etc.--none of which are available in an SCF evaluation.


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