| 摘要 |
A water hydrant defines an elongated flow passage having a water inlet and an air inlet, and a laterally extending water outlet spout disposed therebetween to define an outlet. An elongated rotatable stem is reciprocated within the flow passage, and terminates in an exterior handle. A water inlet valve is connected to the stem for control of flow from the water inlet into the passage and an air valve is connected to the stem to control inflow of air and preclude outflow of water through the air inlet. A first check valve in the spout precludes backflow of water into the passage, movement of the air valve opening the first check valve during operation of the handle. A second check valve in the spout downstream of the first check valve precludes backflow of water into the spout. A drain orifice, open to the atmosphere, extends through the spout between the check valves.
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