Experimental parametric equation for the prediction of valve coefficient (Cv) for choke valve trims

The calculation of nominal choke valve size determines the effective capacity for an oil and gas production system. The degree of restriction for the controlling area in the valve is a function of the surrounding geometry. In an orifice plate this is known as the “velocity of approach” and can be used to determine the meter coefficient (Cm). This paper presents a technique for choke valves, based on the meter velocity of approach parameter, which can be used to predict the Valve Coefficient (Cv) for new trim designs. The prediction method uses a data trend based on a number of flow tests conducted on various trim characteristics. The resultant parametric equation is used to predict the Cv of a new trim geometry. The method relies on experimental data determined per IEC 60534-2-3, with calculations per IEC 60534-2-1. This paper further investigates the effect of varying upstream geometry on Cv for a 4″ nominal valve.