Summary of conversions between SI and US valve coefficients

We may convert this equation to SI units by noting the following conversion factors  

The SI conductance ratio, C (dimensionless) is related to the US liquid-gas-coefficient ratio, C ((scf/US gall).(min/h)/psia ) by 

As discussed above, both Cg and Ci are functions of the ratio of specific heats, y. The quoted values of C and C can be expected to be quoted for air, with. y = 1.4. 

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