Can you briefly analyze the characteristics of the rain alarm valve?

The rain alarm valve is also called the automatic valve of the deluge valve. It can be supplied to the open piping system of the rain system or the automatic water supply control valve of the closed piping system of the preaction system by means of the operation auxiliary mechanism. The flap can be opened electrically, mechanically or otherwise. So what kind of characteristics does it have? The function of the pre-action system is that it can balance both dry and wet systems. In normal pipelines, there is no water. It is linked with the alarm system. Once the alarm is issued, the water can be pre-filled. The nozzle is closed. The system uses a deluge valve. . This system has higher requirements, and the advantage is that there is no water in the pipe, which can prevent accidental spray or cracking. Moreover, the rain system and the pre-action system use different parts, and the designed flow rate and the required water amount are different, which is a big difference. As for the other differences in working principle, it is not too big.