| 摘要 |
<p>[PROBLEMS] To provide a preaction running water detector having a running water detecting means and capable of open/close control of a valve element with a signal in which a means for supplying fire extinguishing water to the secondary side through a simple structure when the pressure in the secondary piping lowers is provided furthermore, and the water flow to the secondary side can be interrupted if running water is detected on the secondary side when no fire occurs. [MEANS FOR SOLVING PROBLEMS] At ordinary times, opening of a valve element (10) is obstructed by a lock mechanism, i.e. a piston (12), and can open only slightly. Open/close control of the valve element (10) can be carried out by supplying/discharging fire extinguishing water filling a control chamber (16) having inner wall along which the piston (12) can slide by means of electric control valves (21A, 21B) to move the piston (12).</p> |
