The wet alarm valve is a key component of the wet automatic sprinkler system. The system pipe network is filled with pressure water, and the system side is kept under pressure due to the function of the check valve of the alarm valve. When a fire occurs in the protected area, the hot air flow rises or the flame burns, the thermal sensitive element of the sprinkler head starts, the sprinkler head continues to spray water, the pressure difference makes the alarm valve flap open, the hydraulic alarm bell alarms, the pressure switch starts, and the linkage starts the pump. Wet system is suitable for ambient temperature of 4~70°C, usually installed in warehouses, hotels, shopping malls, hospitals, office buildings and other high-rise buildings and garages.