The power of the hydraulic alarm bell comes from a small stream of water flowing out of the alarm valve. Pressurized water is ejected from the nozzle through the conduit from the water pipe, impacting the rotation of the water wheel, so that the rotating shaft and the bell hammer tied at the other end also rotate, constantly ringing the alarm bell and giving out an alarm sound.
Hydraulic alarm bell is characterized by simple structure, durability, reliability, high sensitivity and small maintenance workload. Therefore, it is an indispensable part of automatic sprinkler system.
(2) Pressure switch The pressure switch (pressure relay) is generally installed on the pipeline between the delay device and the hydraulic alarm. When the nozzle starts to spray water and the delay device is filled with water, the water flows into the pressure relay, and the pressure relay receives the water pressure signal, that is, the circuit is connected to alarm and the spray pump is started.
A pair of movable contacts are installed inside the pressure, which are often connected with the output/input module of the alarm system in the system to convert the pressure signal into an electrical signal and send a pressure alarm signal to the fire control room.