The alarm valve is the water supply control valve in the wet fire extinguishing system. It makes water flow in one direction and alarms at a certain flow rate.
The working principle of the wet alarm valve is to rely on the reduction or elevation of the water pressure on the side of the pipe network system to open and close the valve disc. In the servo state, when the water supply pressure fluctuates slightly, the function of the bypass balance pipe balances the upper and lower water pressures of the valve disc, and the upper pressure bearing surface of the valve disc is larger than the lower pressure bearing surface, so the valve disc will not open and cause false alarms. When a fire breaks out and the water pressure on the pipe network system side drops due to spraying or blasting, the pressure difference between the water supply side and the system side will open the valve disc to continuously supply water to the opened nozzles to extinguish the fire.
Wet fire extinguishing systems using wet alarm valves must be installed in buildings with an ambient temperature not lower than 4°C to prevent them from losing their fire protection functions due to freezing.
The standard configuration of wet alarm valve includes: pressure gauge, retarder, pressure switch, hydraulic alarm bell, and necessary pipe fittings and valves.
The servo state of the control ball valve between the alarm port of the wet alarm valve and the retarder must be kept fully open and locked, while the test alarm control ball valve must be closed. When a test alarm is required: remove the locking device of the control ball valve between the alarm port and the delayer and close it. At this time, open the test alarm control ball valve to carry out the alarm test. Immediately after the test, restore the two control ball valves to their original condition.