1. Dry sprinkler system: Dry sprinkler system is developed on the basis of wet system to meet the needs of installing automatic fire extinguishing system in cold and high temperature places. The system is composed of closed sprinklers, piping systems, dry alarm valves, alarm devices, inflation equipment, exhaust equipment and water supply equipment. There is no water in the pipeline and nozzle at ordinary times, and it is only in aeration state, so it is called a dry system or a dry pipe system.
The main feature of the dry sprinkler system is that there is no water in the pipeline behind the alarm valve, which is not afraid of freezing and high ambient temperature. Therefore, the system is suitable for buildings and places where the ambient temperature is lower than 4°C and higher than 70°C. Compared with the wet sprinkler system, the dry sprinkler system adds a set of inflation equipment and requires the air pressure in the pipe network to be kept within a certain range. Therefore, the management is more complicated and the investment is larger. The sprinkler speed is not as fast as the wet system.
2. Pre-action sprinkler system: The pre-action system organically combines the automatic fire detection and alarm technology with the automatic sprinkler system, and plays a dual role in protecting the object. The pre-action system consists of closed sprinklers, piping systems, deluge valves, fire detectors, alarm control devices, inflatable equipment, control components and water supply facilities. This kind of system is usually dry, and can realize the initial warning of the fire when a fire occurs, and immediately fill the pipe network with water to convert the system to wet. This transition process of the system contains the function of preparatory action, so it is called a pre-action sprinkler system. The system is in the pipeline behind the deluge valve and is usually filled with low-pressure gas. When a fire occurs, the temperature and smoke detectors installed in the protection area first send out the fire alarm signal, and the controller turns on the alarm signal while displaying the sound and light. The deluge valve allows water to enter the pipeline and completes the water filling process in a short time, turning the system into a wet system. The subsequent actions are the same as the wet system.
3. The main features of the pre-action system are:
(1) Compared with the wet system, this system usually does not fill water in the pipe network after the pre-action valve, but is filled with low pressure air or nitrogen, or dry pipe. Only in the event of a fire, the fire detection system automatically opens the pre-action valve to fill the pipe with water and become a wet system. The pipe network is usually without water, which can avoid water damage caused by system damage.
(2) In addition, this kind of system has an early warning device, which can alarm in time before the sprinkler moves, so as to organize an early rescue. In contrast, the wet system must give an alarm after spraying water.