Abstract: A bi-directional flow-control device includes a housing defining a flow passage and first and second orifices installed in the passage, each orifice being tubular and having a seat, each seat having a plurality of circumferentially spaced flow-control channels, the seat of the second orifice being axially spaced from and facing the seat of the first orifice. A resiliently deformable diaphragm is disposed between the seats, whereby flow through the passage in a first direction urges the diaphragm against the seat of the first orifice and flow through the passage in an opposite second direction urges the diaphragm against the seat of the second orifice. The diaphragm in each case deforms into the channels in the seat to varying degrees as a function of pressure differential such that in either flow direction the flow is regulated to a substantially constant volumetric flow rate over a range of pressure differentials.

Abstract: A method and system for producing constant-flow valves having a plurality of different flow rates includes a plurality of orifices each having a seat defining contoured flow control surfaces, the orifices having at least K different configurations of flow control surfaces, where K≧2, and a plurality of diaphragms of identical shape each formed of an elastomeric material having a defined Shore A durometer hardness, the diaphragms having at least M different Shore A durometer hardnesses, where M≧2, each diaphragm being configured to engage the flow control surfaces of the seat of each orifice so as to create flow control passages between the diaphragm and the flow control surfaces, the diaphragm being deflected by pressure differential across the diaphragm so as to constrict the flow control passages as the pressure differential increases.