Manual Diaphragm Valve

Manual Diaphragm Valve

Manual diaphragm valve uses synthetic rubber diaphragm to separate fluid medium and valve element in valve body. When compressed, the diaphragm valve is pushed to the bottom of the valve body to block the flow of medium.

Manual Diaphragm Valve Design

Two typical structures of manual diaphragm valve are straight through structure and weir structure. Weir diaphragm valve and straight through diaphragm valve have similar structure except valve body and diaphragm. There is a painted lip on the valve body which is lifted up to meet the diaphragm. The valve body is self draining, so it is ideal for the food industry. Because the diaphragm can be made of stronger materials, the valve body can also be used for high pressure conditions. 

Straight through diaphragm valve, the bottom wall of the valve body is almost parallel to the fluid, so that the medium can pass through the valve unimpeded without great interference. The elasticity of the diaphragm allows it to move to the bottom of the valve body. 

Above the diaphragm is the compressor, a round part that is shaped like the flow passage of the valve body and connected to the handwheel rod. The diaphragm is installed at the bottom of the compressor to ensure that the diaphragm can be lifted away from the medium when it is in the fully open position. The compressor is a valve part that does not contact with the medium, and the handwheel mechanism is located in the valve cap connected with the valve body by bolts. The diaphragm itself is used as a gasket between the body and bonnet to prevent leakage to the atmosphere.

How Does a Manual Diaphragm Valve Work

The operation of manual diaphragm valve is similar to that of hose valve. Rotate the handwheel to lower the compressor and begin to push the diaphragm toward the bottom wall of the valve body. In throttling state, the manual manipulator rotates to the required flow and stays there. In the on-off state, when the maximum pressure is reached, the two surfaces are tightly sealed. When the diaphragm valve is opened, the rotation effect of the manual manipulator is on the contrary. When the closing element is lifted, the flow area is enlarged. Finally, in the fully open position, the compressor fully retracts into the bonnet and the diaphragm is away from the medium. In this position the valve reaches its full area capacity. In short, diaphragm valves provide inherent equal percentage flow characteristics, which tend to move in a straight line during operation.