Alarm valve is the automatic sprinkler system to turn on or off the water, and start the alarm device. In sprinkler system, the alarm valve is a vital component, its role in three: turn on or off the water, the output alarm signal and prevent the water back to the water supply, and through the alarm valve on the system water supply and alarm Device inspection. Alarm valve according to the system is divided into different types of wet alarm valve, dry alarm valve and deluge valve. 1. Wet alarm valve for wet sprinkler system. Its main function is: When the nozzle is turned on, the wet valve can open automatically, and make the water flow into the hydraulic alarm to send the alarm signal. 2. Dry alarm valve for dry sprinkler system. Its valve flap divides the valve into two parts, the outlet side is connected with the system piping and the nozzle, the compressed air is filled in the inlet, and the inlet side is connected with the water source. Dry valve on both sides of the pressure and water pressure on the valve flap torque control valve flap closed and opened, generally can be divided into differential dry-type alarm valve and closed-type dry alarm valve two. 3. Deluge valve for rain sprinkler system, pre-action sprinkler system, water curtain system and water spray off system. The inlet side of this valve is connected to a source of water and the outlet side is connected to a system line and a showerhead, generally empty, only inflated in the preaction system. Deluge valve open by a variety of fire detection device control.