湿式报警阀是湿式灭火系统中的供水控制阀，它使水单向流动，并在一定的流量下报警。

湿式报警阀的工作原理是依靠管网系统侧水压的降低或升高启闭阀瓣，在伺应状态下，供水压力稍有波动时，旁路平衡管的作用使阀瓣上下水压平衡，而阀瓣上承压面大于下承压面，阀瓣不会打开发生误报警，当发生火灾有喷头爆破造成管网系统侧水压下降时，供水侧和系统测产生的压差就会将阀瓣打开向打开的喷头连续供水灭火。

采用湿式报警阀的湿式灭火系统，必须安装在环境温度不低于 4℃的建筑内，以免其因结冰而失去消防功能。

湿式报警阀的标准配置包括：压力表、延迟器、压力开关、水力警铃．以及必要的管件和阀门。

湿式报警阀报警口与延迟器之间的控制球阀伺应状态必须保持全开并锁紧，而试报警控制球阀必须关闭。需要进行试报警时．拆卸报警口与延迟器之间控制球阀的锁紧装置并将其关闭。此时打开试报警控制球阀即可进行报警试验。试验后立即将两个控制球阀恢复至原来状态。

Wet alarm valve is the water supply control valve in wet fire extinguishing system,which make the water flow in single direction and alarm under certain flow.

The working principle of wet alarm valves: relying on the on and off of valves flap caused by the up and down of water pressure from pipe network system, when in the waiting state, a little diviation of water pressure, the balance pipe will balanced the water pressure on the up and down side of valves flap, while the upside pressure bearing area is biger than downside pressure area, the valves flap will not open and wrong alarm will no happen. When fire happens, sprinkler exploded and makes the water pressure down on the side of pipe network system, the pressure difference between water supplying side and system side will open the valves flap and continuously supplying the water to the sprinkler to protect from fire.

When wet fire extinguishing system has adopted wet alarm valve,it shall be mounted in the building with environment temperature no less than 4℃ ,in case losing fire control function by freezing.

configuration of wet alarm valve shall be composed by pressure gauge, delayer, pressure switch, water motor alarm,and necessary pipe fittings and valves.

Ready condition of control ball valve between alarm entrance and delayer of wet alarm valve shall be open and locking,while trial alarm control ball valve shall be close.When trial alarm is under operation,locking device of control ball valve between alarm entrance and delayer shall be dismounted and close.Alarm test can be carried out,by opening trial alarm control ball valve.After the test has been finished,the two control ball valves shall be recovered to their original state.