| 摘要 |
An automatic water supply shutoff valve for use with a fire protection piping system has a body defining a cavity communicating among a supply inlet connected to a water supply, an ancillary outlet connected to ancillary piping, and a fire protection outlet connected to fire protection piping; and a piston within the cavity defining a piston passageway. The piston moves between a first position connecting the supply inlet and ancillary outlet and a second position connecting the supply inlet and fire protection outlet. The piston moves in response to biasing forces acting against the piston, including a first biasing force from the supply inlet, a second biasing force from the fire protection outlet, and a third biasing force. The first biasing force, urging the piston toward its second or fire protection position, is opposed by a combination of the second and third biasing forces, together urging the piston toward its first or ancillary position. The piston has an inlet communicating between the supply inlet and piston passageway, and a plurality of radial piston outlets, which, in first position, communicate between the piston passageway and ancillary outlet, and which, in second position, communicate between the piston passageway and fire protection outlet.
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