| 摘要 |
<p>A normally open non-electric valve includes a flow path through an apertured valve seat. A cavity isolated from the flow path is sealingly closed off adjacent the valve seat by a flexible diaphragm. The diaphragm is sufficiently flexible to be pushed and held away from the valve seat by fluid flowing in the flow path. When it is desired to close the valve, a pressure medium is introduced into the cavity so as to force the diaphragm against the valve seat and interrupt the fluid flow in the flow path. The normally open valve can inexpensively be converted from an inexpensive electric solenoid valve by removing the plunger, spring and coil from the electric valve, closing off the plunger cavity with a flexible diaphragm, and selectably introducing a pressure medium into the cavity when it is desired to close the valve.</p> |
