Diaphragm valve with flow control stem air bleed

A valve, comprising:

• a diaphragm assembly;
• a valve housing having an inlet passage and an outlet passage, the diaphragm assembly being reciprocable back and forth within the valve housing to thereby connect and disconnect the inlet passage and the outlet passage, the valve housing having a lower inlet chamber below the diaphragm assembly, an upper pressure control chamber above the diaphragm assembly, and a bore communicating with the upper pressure control chamber;
• a pilot valve operatively associated with the upper pressure control chamber for selectively venting pressurized water therefrom;
• the diaphragm assembly normally sealing the inlet passage from the outlet passage and being moveable in a first direction to connect the inlet passage with the outlet passage upon release of a sufficient amount of pressurized water from the upper pressure control chamber via the pilot valve;
• the diaphragm assembly including means for metering water from the lower inlet chamber through the diaphragm assembly into the upper pressure control chamber;
• and
• means connected to the diaphragm assembly for selectively venting air trapped in the upper pressure control chamber including a flow control stem vertically reciprocable in the bore of the valve housing.

A method of bleeding air from a diaphragm valve to ensure optimum operation thereof, comprising the steps of:

• providing a valve housing with a bonnet and a base section, the base section having an inlet port and an outlet port, and the bonnet having a neck in an upper central region thereof defining a bore;
• mounting a diaphragm assembly inside the valve housing to define a lower inlet chamber and an upper pressure control chamber that communicates with the bore, the diaphragm assembly being moveable vertically to seal and unseal a liquid flow path between the inlet port and the outlet port and including a metering body for permitting liquid to gradually flow from the lower inlet chamber through the diaphragm assembly to the upper pressure control chamber;
• coupling a pilot valve to the upper pressure control chamber;
• mounting a flow control stem in the bore, the flow control stem being connected to the diaphragm assembly and being moveable from an upper extended position in which it seals the bore to a lower retracted position in which air trapped in the upper pressure control chamber can be bled out through the bore;
• and
• momentarily depressing the flow control stem to move the stem to its lower retracted position to allow trapped air to escape through the bore.