When the fixed temperature release (1) is activated by fire pressure in the release system escapes from the open device allowing the pneumatic actuator to open. The release pressure from the priming chamber of the deluge valve (2) allowing the valve to open. Water flows in to the system piping (3) and to the alarm device, pressurizing the pressure switch to activate an electric alarm and operating a mechanical water motor alarm. Water flows from all open sprinklers or nozzles (4). When the deluge valve operates is a pressurized closed, closing the supply of water to the priming chamber latching the deluge valve in the open position.
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Deluge systems are used where conditions of occupancy or special hazards require quick application of large quantities of water. These systems are used to create a buffer zone in high-hazard areas or in areas where fire may spread rapidly, and they can also be used to cool surfaces to prevent deformation or structural collapse or to protect tanks, process lines, or transformers against explosion. Other examples include storage or process areas containing substances having a low flash point; tanks containing combustible solutions, equipment pits or product handling systems. When designing a deluge system, efforts should be made to acquire specific information regarding the hazard to be protected.
Foam-water deluge systems are those using foam-water sprinklers or spray nozzles and an air-foam concentrate which is introduced into the water at controlled rate on the system side of the deluge valve. Foam water systems are used to control and/or extinguish fires which require a smothering and cooling agent. Examples are: extraction plants, aircraft hangars and areas where flammable-liquid spill fires may occur.
A Deluge System is a fixed fire protection system in which the pipe system is empty until the deluge valve operates to distribute pressurized water from open nozzles or sprinklers. Deluge systems are more complex than wet pipe and dry systems because they contain more components and equipment. The deluge valve is activated by operation of a fire detection system installed in the same area as the sprinklers. Various types of detection systems may be used, including smoke, heat, ultraviolet (UV), or infrared (IR) detection. The deluge system can be activated by a hydraulic, pneumatic, electric, or manual release system or any combination of these release systems. But, in all cases, the deluge valve itself is activated hydraulically. When the detection device is activated, the deluge valve is tripped and water flows into the piping system, discharging through all spray nozzles or sprinklers simultaneously.
Section 7.3 of NFPA 13-2007 provides the installation rules and characteristics that are unique to deluge systems. Also, refer to NFPA 72 National Fire Alarm Code for specific requirements on the design of hydraulic, pneumatic, and electrical detection systems.
Deluge systems are required to be hydraulically calculated. Since all sprinklers are open, every sprinkler on the system discharges water simultaneously when the deluge valve operates. Note: The system’s area of operation is easy to determine; it is the entire area protected by the deluge system. Chapter 22 of NFPA 13 discusses the procedures for calculating the hydraulic demand of the sprinkler system and for verifying whether the available water supply will meet the requirements.