Fluid flow control valve and orifice therefor

摘要

A fluid flow control valve comprises a housing defining a fluid flow passage extending longitudinally therethrough, the housing having opposite ends each defining an opening for flow into and out of the fluid flow passage, and an orifice and diaphragm disposed in the housing. The orifice has a seat at one end thereof facing the diaphragm. The diaphragm has one end face that opposes the seat of the orifice, the seat being configured such that one or more flow control passages are defined between the seat and the one end face of the diaphragm through which the fluid flows. The seat is contoured to include at least two different shapes of channels each promoting localized bending of the diaphragm at a different pressure differential, thereby permitting an expansion of the working pressure range to very low pressure differentials. The localized bending of the diaphragm can be modeled as a simple supported beam bending, which is well understood and readily predicted, thus making the prediction of the diaphragm movement more accurate than prediction of complex diaphragm deflections that occur in many prior flow control valves. Accordingly, the accuracy of the flow control valve can be improved over that of prior valves having complex diaphragm deflection modes.