What is meant by deluge fire fighting system and when it is used?

Deluge Fire Sprinkler System

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.

In these systems, sprinklers are open at all times.

They are connected to a dry pipe that is connected to a main water supply. A fire detection device controls the main valve.When it is activated, the valve opens, allowing large amounts of water to flow through all of the sprinklers. The purpose of a deluge system is to quickly wet down an entire hazard area to prevent a fire from spreading. They are usually used in facilities that contain hazardous materials such as: flammable liquids,chemicals, and explosives.

 

Rooms with high ceilings sometimes use deluge systems, as it is difficult to direct water over the burning area from such a distance.

In Deluge systems, we use open sprinklers or nozzles and a deluge valve to control the fire.
when a fire is detected (by means of a fire detector) a signal is sent to the deluge valve to open.
When it opens, water flows into the piping system and discharges from all sprinklers at once.
Deluge systems are used where large quantities of water are needed quickly to control a fast-developing fires.

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deluge system : open sprinklers at all times without glass bulb or heat sensitve element 

Used in expensive commodities and industrial application 

Deluge fire fighting system is quite a rare system to evidence.

However I am lucky enough to work on installation of deluge water fire fighting system.

First of all deluge fire fighting system can be used along with wet sprinkler system.

Secondaly in deluge system a special kind of sprinkler is used known as deluge sprinkler which is always open and pipe remains empty. Water is stopped by a deluge valve which can be actuated pneumaticaly, electricaly or hydraulically.

During fire, Smoke/heat detector detects the fire and help actauting the deluge valve.

Once activated and used deluge valve can be easily reset to normal operation by draining the water inside the pipe and body of valve through drain valve provided in deluge valve arrangement and restoring the detector by cleaning.

Deluge system is used where quick response and high intensity of water required.

We have installed deluge water system in NOC room of a data center. 

I experienced deluge system with Infra red (IR) & Ultravoilet (UV) detectors, found highly effective & quick responsive for any type of fire.