Preacting system is an automatic water spraying and water extinguishing facility that has been developed in recent years. It combines fire detecting and alarming technology with automatic water spraying and fire extinguishing system, thus double-protecting the objects. When there is not fire, the pipelines of the system are full of gas. Therefore, the system has the characteristics of dry system, and meets the requirement of automaticwater spray and fire protection under high-temperature or cold conditions.Once fire happens, the temperature and smoke detectors installed in the protection area will send out fire-alarming signals first; upon receiving fire-alarming signals, the fire controller will send out command signal to open the shower valves; before the closed shower nozzles are opened, the controller supplies water to the pipelines on the system side, so that the system turns into a wet system. Meanwhile, the pressure switch of the system acts and displays that the pipelines are full of water, and the water alarm bells ring. At this moment, if the fire continues, the crystal balls of the open water nozzles break; the water sprays automatically; and the water pumps work automatically. Shower valve facility is widely used in shower system, water film system and water system. On the pipelines on the system side are all open nozzles (water film nozzles, water nozzles, common open nozzles, etc.). The startup of the shower valve facility is controlled by the on-site fire detection system. When fire happens in the protection area, the environmental temperature rises, and the fire detection system acts to open the shower valve facility.