| 摘要 |
An automatically-resettable fire sprinkler valve is normally held closed by a piston-cylinder unit in which both ends of the piston are exposed to the high main-supply water pressure, one of the piston ends being of greater effective area than the other, such that the same water pressure acting on the different end areas normally forces a valve member to a flow-blocking position. A normally-closed bleed port associated with the broader-area end of the unit is valved open to a pressure-relieving condition by mechanical response of a thermal actuator to temperatures above a predetermined critical level, whereby the sprinkler valve is forced open by the main-supply pressure; when the temperature decreases to a safe low level, the bleed port is automatically closed by the thermal actuator, and equal pressures on the unequal-area piston ends cause positive reclosing of the sprinkler valve.
|
