VALVE AND METHOD FOR CONTROLLING PRESSURE AND FLOW

摘要

A variable restrictor valve (48) for use in an intermittent dispensing system (10) having a recirculation loop. The restrictor valve (48) establishes a more linear relationship between the amount of adjustment made thereto and the resulting pressure drop over the restrictor valve (48) in the recirculation loop. A first embodiment of the restrictor valve changes the length of the flow path created by a helical groove (136a) to thereby adjust the flow resistance through the valve. A second embodiment uses a valve member (146) in the form of a perforated cylindrical tube which is adjustable to present a varying number of perforations (146a) as the inlet to the tube and thereby allow adjustment of the flow resistance. A third embodiment utilizes a helical spring (156) as a valve member in which adjustable spacing (156a) between the coils of the spring (156) provides adjustability of the flow rate through the spring (156).