Constant-rate flow control valve

Abstract

An apparatus to control fluid flow to an approximate fixed rate is disclosed. The apparatus includes a housing (12), an orifice (22), a diaphragm (24), and a cage (26). The housing has two ends, an inlet end (18) having an inlet opening and an outlet end (20) having an outlet opening. The ends are arranged and configured to receive piping (14 and 16). The orifice is disposed within the housing. The orifice has an upstream end and a downstream end with a seat (34) formed in the upstream end. The fluid flows over the seat and through the orifice before exiting the outlet end of the housing in normal flow. The diaphragm is disposed within the housing adjacent and upstream of the seat of the orifice. The diaphragm has an upstream side, a downstream side, and sidewalls. The downstream side of the diaphragm is opposite the seat such that a pressure drop across the diaphragm pulls the downstream side of the diaphragm toward the seat. The cage surrounds at least a portion of the sidewalls of the diaphragm. The cage has ribs (38) projecting toward and contacting the sidewalls of the diaphragm to hold the diaphragm away from the housing and to allow reduced flow restriction between the housing and the sidewalls.