Vapor flow rating of valves using small pressure reservoirs

Abstract A new method for the determination of valve coefficients for choked vapor flow is presented. The procedure is based on the non-steady equations governing isentropic critical flow of gases from finite sized pressure vessels, and can be extended to subcritical vapor flow. This method has two advantages. A relatively small pressure vessel, i.e., a time dependent upstream reservoir, takes the place of a large continuous flow loop, and only the pressure decay in the vessel need be accurately measured, instead of mass flow rates and stagnation conditions.