| 摘要 |
A hydraulic diaphragm valve comprising a housing, an inlet, an outlet, a diaphragm valve seating between the inlet and the outlet, a sealing diaphragm mounted in the housing and displaceable about the diaphragm valve seating, so as to close and open a flow path between the inlet and outlet, a valve control chamber and a command valve comprising a first duct communicating a one end thereof with the valve inlet, and at an opposite end thereof with a first command valve seating, a second duct communicating into one end with the valve outlet, and at an opposite end thereof, with a second command valve seating. A third duct communicates at one end with the valve control chamber and at its opposite end it selectively communicates with the first and second command valve seatings. A flexible command diaphragm is selectively biased into sealing engagement with one or other of the command valve seatings to effect communication between the third duct and the command valve seating not in seating engagement with the command diaphragm.
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