Automatically venting backpressure valve for use with fluid metering pump, e.g. solenoid driven liquid metering pump has valve body including gas by-pass orifice

摘要

An automatically venting backpressure valve comprises (a) a valve body having a lower inlet opening, an opposed upper outlet opening, a side opening, a stepped recess, an inlet and product outlet passageways, and a gas by-pass orifice; and (b) a spring-loaded pressure diaphragm against the bearing surface and covering the side opening. An automatically venting backpressure valve (40) comprises a valve body and a spring-loaded pressure diaphragm assembly (44). The valve body has a lower inlet opening (48), an opposed upper outlet opening (50), a side opening (56), a stepped recess (58), an inlet (70) and product outlet (74) passageways, and a gas by-pass orifice (82). The lower inlet opening is sealably connectable to a product discharge outlet of a fluid metering pump. The stepped recess is disposed inwardly adjacent the side opening to define a bearing surface (60). The bearing surface has an annular recess (62) defining a central cylindrical portion (64). The central cylindrical portion has an end sealing surface (66) with an exit opening (68). The end sealing surface is spaced inwardly from the bearing surface. The inlet passageway extends from the lower inlet opening to a first opening in a lower portion of the annular recess. The product outlet passageway extends from the opening in the end sealing surface to the upper outlet opening. The gas by-pass orifice extends between a second opening in an upper portion of the annular recess and the product outlet passageway. The spring-loaded backpressure diaphragm assembly is disposed against the bearing surface and covering the side opening. The backpressure is movable in response to increasing pumping fluid pressure in the product inlet passageway between a normally closed and open positions. The back pressure abuts the opening in the end sealing surface to close off the product outlet passageway in the normally closed position and is spaced from the opening in the end sealing surface to open the product outlet passageway in the open position. The gas by-pass through the orifice with a diametrical dimension so that gases pass through the orifice but not the liquids. Preferred Features: The backpressure valve also comprises a manual override lever connected to the backpressure assembly that is manually manipulatable to override the spring to maintain the backpressure assembly in an open position.