A deluge fire sprinkler system is similar to a pre-action system except the sprinkler heads are open and the pipe is not pressurized with air. Deluge systems are connected to a water supply through a deluge valve that is opened by the operation of a smoke or heat detection system. The detection system is installed in the same area as the sprinklers. When the detection system is activated water discharges through all of the sprinkler heads in the system. Deluge systems are used in places that are considered high hazard areas such as power plants, aircraft hangars and chemical storage or processing facilities. Deluge systems are needed where high velocity suppression is necessary to prevent fire spread.
Deluge Fire Sprinkler Systems differ from conventional Fire Sprinkler Systems in the sense that all nozzles employed in the system are open and when water is released into the system it flows from all discharge devices. As such, this special type of system is generally found within industrial type hazards that require the application of water over a large hazard or area. The control of water is accomplished by the use of a Deluge Valve which is a device that prevents water from entering the system piping until required. A detection system which may incorporate the use of heat, smoke, or flame detectors is used to open the Deluge Valve when a fire or its products of combustion are detected. All system piping is filled with water which discharges from the open sprinklers and nozzles used in the system. In addition to the application of water some deluge systems will incorporate the use of a foam concentrate to mix with water and form a foam solution which can then provide a protective blanket of foam to help control the development of a fire.
Deluge Fire Sprinkler systems protect extra hazard occupancies that require significant amounts of water to cool and control the growth or development of a fire. Typically they are employed on hazards that contain low flash point flammable liquids or hazards with large amounts of combustible liquids. These types of hazards may include, oil extraction processes, transformers, tank or vessel protection, distillation processes. Water or Foam Deluge systems are used in the protection of large Aircraft Hangers as one primary means of fire protection.