濕式報警閥是濕式滅火系統中的供水控制閥，它使水單向流動，并在一定的流量下報警。

濕式報警閥的工作原理是依靠管網系統側水壓的降低或升高啟閉閥瓣，在伺應狀態下，供水壓力稍有波動時，旁路平衡管的作用使閥瓣上下水壓平衡，而閥瓣上承壓面大于下承壓面，閥瓣不會打開發生誤報警，當發生火災有噴頭爆破造成管網系統側水壓下降時，供水側和系統測產生的壓差就會將閥瓣打開向打開的噴頭連續供水滅火。

采用濕式報警閥的濕式滅火系統，必須安裝在環境溫度不低于 4℃的建筑內，以免其因結冰而失去消防功能。

濕式報警閥的標準配置包括：壓力表、延遲器、壓力開關、水力警鈴．以及必要的管件和閥門。

濕式報警閥報警口與延遲器之間的控制球閥伺應狀態必須保持全開并鎖緊，而試報警控制球閥必須關閉。需要進行試報警時．拆卸報警口與延遲器之間控制球閥的鎖緊裝置并將其關閉。此時打開試報警控制球閥即可進行報警試驗。試驗后立即將兩個控制球閥恢復至原來狀態。

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.