Diaphragm valves, such as diaphragm gas valves and diaphragm liquid valves, have long been used to control fluid flow in a wide variety of home and industrial applications. For example, diaphragm gas valves are used with atmospheric boilers, commercial water heaters, duct furnaces, makeup air and rooftop heaters, to name but a few.MUD VALVES In conjunction with these various applications, diaphragm gas valves are typically suitable for controlling liquefied petroleum (LP), natural, and manufactured gases.

Generally speaking, diaphragm gas valves are designed to regulate gas flow, and/or serve as safety shutoffs. Depending upon size and operating conditions, diaphragm gas valves are normally rated for use with gas line pressures in the range of 0.5-5 psi (3.4-34.5 kPa). As described below, certain inherent design constraints prevent diaphragm gas valves of conventional design from being used in higher pressure applications. For high pressure gas flow control, a motorized gas valve is generally employed. Motorized gas valves, while effective, are more complex, and therefore expensive, than diaphragm gas valves.

Regardless of the exact application or function, diaphragm valves share a relatively standard component configuration and arrangement. Safety valves A diaphragm valve normally includes a valve housing, a flexible diaphragm and a control assembly. The valve housing is defined by an upper housing section and a lower housing section that mate with one another, forming a fluid inlet, a fluid outlet and a valve seat. The valve seat is positioned between the fluid inlet and the fluid outlet such that fluid flows from the fluid inlet, through the valve seat, to the fluid outlet. The diaphragm is sealed between the two housing sections, adjacent the valve seat. This arrangement creates an upper control chamber above the diaphragm (i.e., between the diaphragm and the upper housing section) and a lower working chamber below the diaphragm (i.e., between the diaphragm and the lower housing section). Finally, the control assembly is associated with the valve housing and controls movement of the diaphragm. One typical form of a control assembly is a pilot operator valve that includes a fluid connection to the working chamber for sampling fluid entering the valve housing, a fluid connection to the control chamber for directing movement of the diaphragm via the control chamber, and a bleed port fluidly connected to atmospheric pressure. Cast Steel Valves A solenoid pilot valve closure assembly or similar mechanism within the control assembly dictates a valve open or valve closed state of the diaphragm valve.

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