Anti-contaminant diaphragm valve

Claim 1

A solenoid valve comprising a valve body having an annular inlet and an outlet centrally located relative to the inlet, a diaphragm mounted in the body overlying both the inlet and the outlet, a valve seat between the inlet and the outlet and having a resilient face adapted to close on said seat, a rigid insert molded in the diaphragm, a central vent hole through the diaphragm and insert, a solenoid assembly including a watertight plunger guide and a coil surrounding the guide, the guide cooperating with the diaphragm to define a chamber the contents of which may flow through the vent hole when the hole is open, a plunger slidable in the guide and having a valve portion normally closing the vent hole but movable upon energization of said coil to open the vent hole, a bleed hole in said insert outside the portion overlying said valve seat, a groove in said resilient face communicating with said bleed hole whereby fluid may flow from the inlet through the groove into the bleed hole and then into said chamber, the width of said groove being less than the diameter of the bleed hole whereby entrained particles which pass through the groove will pass throuogh the bleed hole while larger particles are rejected or lodge in the groove.