Patent ID: 6866061
Filing Date: 2005-03-15
Classification: G05D,Y10T

Abstract:
1. A back pressure valve, comprising: (a) a first housing including a first chamber formed therein having a fluid inlet and a fluid outlet for a first fluid, the fluid outlet being an outlet of the back pressure valve; (b) a second housing including a second chamber formed therein; (c) a flexible diaphragm having an outer peripheral edge portion abutting the second housing and closing off the second chamber; (d) a back pressure member moveably disposed in the first chamber of the first housing for controlling fluid flow between the fluid inlet and the fluid outlet, wherein the first chamber is defined by the first housing and the back pressure member; and wherein the flexible diaphragm is fixed onto and moveable together with the back pressure member, whereby pressure in the second chamber determines fluid pressure required to maintain the back pressure member in a steady position; (e) a reference inlet and a reference outlet, for a reference fluid, provide in the second housing, and a control valve means in the second housing connected to the reference inlet and the reference outlet, for controlling the pressure in at least part of the second housing applied to the flexible diaphragm and the back pressure member;