A diaphragm valve is provided with an improved sealing surface and a mechanical flow regulator for precise flow control.REDUCING VALVES The valve has a body with an inlet chamber and an outlet chamber. Passages extend from both chambers to at least one side of the body. The passages are covered by a diaphragm which in turn is covered by a cap. The cap and diaphragm define a control cavity which may be pressurized to force the diaphragm against the side of the body, thereby closing the valve. The openings from the passages are surrounded with ridges, which reduce the effective sealing area against which the diaphragm presses. The cap also supports a mechanical flow regulator which presses the diaphragm towards the body of the valve between the passages from the inlet chamber and the passages to the outlet chamber.

Diaphragm valves are used in a variety of fluid flow systems because they can be made to withstand corrosive conditions and because they can handle abrasive fluids. Forged Steel ValvesOne common type utilizes a body with an inlet port or chamber, an outlet port or chamber and a number of small passageways from both ports to at least one side of the body. A diaphragm is pressed by fluid pressure behind the diaphragm against the side of the body to close the valve, and permitted to flex away from the side of the body to permit fluid to flow from the inlet port through the small passageways to the outlet port. Valves of this type are shown in U.S. Pat. Nos. 2,786,642; 2,818,880 and 3,092,144.

Since the diaphragms in valves of this type only have to bridge small openings, the need for rigidity and strength in the diaphragms is reduced.Forged Steel Valves As a result, these valves offer better seals and less likelihood of diaphragm rupture. However, in this type of valve, the sealing surface, i.e., the area against which the diaphragm is pressed, is relatively large. As a result, the pressure needed to seal the valve is higher than it would be if the effective sealing area were smaller. It is an object of this invention to provide a valve with a smaller effective sealing area.

Another drawback of conventional diaphragm valves of this type is the fact that they are basically on-off devices. It is true that a certain amount of control can be achieved by varying the pressure behind the diaphragm, but the degree of control afforded in this manner is not sufficient to make the valves suitable for close flow control. Another object of this invention is to provide a diaphragm valve that does provide accurate flow control.

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