Patent ID: 6427967
Filing Date: 2002-08-06
Classification: F16K

Abstract:
A valve system comprising:a) a housing having a hollow interior within an outer housing surface, b) a diaphragm extending across the hollow interior and creating a control chamber within the hollow interior, c) a valve seat against which a part of the diaphragm can seal, d) a first conduit leading around at least part of the valve seat, e) a second conduit leading to within the valve seat, f) a diaphragm control means for controlling the flow of fluid into the control chamber, wherein said control chamber is isolated from the first and second conduits, g) an inlet fluid conduit connected to one of the first and second conduits through which fluid can flow towards the diaphragm valve, h) a pressure selection means having an outlet connected to the control chamber, and a plurality of inlets, each inlet being connected to a respective pressure source, one of the inlets being connected to the inlet fluid conduit and another of the inlets being connected to an independent pressure source, each inlet having a pressure responsive means, the pressure responsive means of the inlet connected to the highest source pressure automatically communicating this pressure to the control chamber by way of the outlet.