| 摘要 |
A pilot operated sprinkler head comprises a two part housing having an annular diaphragm extending across a chamber between the housing parts, the diaphragm being sealed to a hollow bore main valve member and sealed to the chamber; one side of the diaphragm is exposed to the discharge of a pilot valve assembly for actuating the main valve member when the pilot valve is open; and a drain passage of restricted size to the atmosphere is provided between the housing and the main valve member, sized to insure proper pressure on the diaphragm to actuate the main valve member with the pilot valve open, the drain passage draining water from the diaphragm when the pilot valve is closed to permit the diaphragm and the main valve member to return to their original positions. The drain passage is shown in the form of an annular clearance around the valve member. The valve member is shown with hollow bore axially aligned with the inlet, and telescopically movable about a stationary strainer. The valve member is biased closed with a strong spring which is overcome by the action of water pressure on a large diaphragm area, the latter being vented on its opposite side.
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