| 摘要 |
An improved pneumatically operated valve for controlling supply of fluid to a certain apparatus adapted to be operated for an intended purpose using the thus supplied fluid. The valve includes a valve portion on the piston rod and a flow passage of fluid is normally kept in the opened state or in the closed state by means of the valve portion under the effect of a force exerted on the piston in a predetermined direction. When any abnormal fluctuation of pressure of fluid is detected, pressurized air is introduced into the interior of the casing so as to exert its pressure on the piston against the aforesaid force on the piston, whereby the flow passage is shifted from the opened state to the closed state or from the closed state to the opened state. Both a normally opened type pneumatically operated valve and a normally closed type pneumatically operated valve can be constituted using parts and components having the same shape and dimension merely by changing the direction of assembling of a certain member. |
