Operation and Deluge system

Deluge

"Deluge" systems are systems in which all sprinklers connected to the water piping system are open, in that the heat sensing operating element is removed, or specifically designed as such.These systems are used for special hazards where rapid fire spread is a concern, as they provide a simultaneous application of water over the entire hazard.They are sometimes installed in personnel egress paths or building openings to slow travel of fire (e.g. openings in a fire-rated wall).Water is not present in the piping until the system operates.Because the sprinkler orifices are open, the piping is at atmospheric pressure.To prevent the water supply pressure from forcing water into the piping, a "deluge valve" (a mechanically latched valve) is used in the water supply connection.It is a non-resetting valve, and stays open once tripped.Since the heat sensitive elements normally present in automatic sprinklers have been removed (causing the sprinkler heads to open), the deluge valve is opened by a signal from a fire alarm system using fire detectors. The type of fire alarm actuating device is selected primarily based on the hazard (eg pilot sprinkler, smoke detector, heat detector or optical flame detector).The triggering device signals the fire panel which in turn signals the deluge valve to open.Can also be activated by an electric or pneumatic fire alarm pull station which signals the fire alarm panel to open the deluge valve.

Pre-action 

Pre-action sprinkler systems are designed for use in places where accidental activation is particularly undesirable,such as in museums with rare works of art, manuscripts, or books; and data centers, to protect computer equipment from accidental water discharge.Pre-action systems are hybrids of wet, dry, and deluge systems,depending on the exact system goal.There are two main sub-types of pre-action systems: single interlock, and double interlock.The operation of single interlock systems are similar to dry systems except that these systems require that a "preceding" fire detection event, typically the activation of a heat or smoke detector takes place prior to the "action" of water introduction into the system's piping by opening the pre-action valve which is a mechanically latched valve (i.e. similar to a deluge valve).In this way, the system is essentially converted from a dry system into a wet system.The intent is to reduce the undesirable time delay of water delivery to sprinklers that is inherent in dry systems.Prior to fire detection, if the sprinkler operates, or the piping system develops a leak, loss of air pressure in the piping will activate a trouble alarm. In this case, the pre-action valve will not open due to loss of supervisory pressure, and water will not enter the piping.Double interlock systems require that both a "preceding" fire detection event, typically the activation of a heat or smoke detector, and an automatic sprinkler operation take place prior to the "action" of water introduction into the system's piping.Activation of either the fire detectors alone, or sprinklers alone, without the concurrent operation of the other will not allow water to enter the piping.Because water does not enter the piping until a sprinkler operates, double interlock systems are considered as dry systems in terms of water delivery times, and similarly require a larger design area.

Electronic

An electronic sprinkler system is a system that includes sprinklers in which the thermally sensitive operating elements are replaced by electronic sensing and electronic trigger actuation.Sprinkler operation is usually controlled by an algorithm that determines which sprinklers will operate when.These systems are often used in scenarios requiring fast response and controlled spray operation, such as high-ceiling pallet racks for storing fast-burning commodities or dense storage applications.

Foam water

A foam water fire sprinkler system is a special application system that discharges a mixture of water and low expansion foam concentrate, causing the sprinklers to spray foam.These systems are often used in special hazard locations associated with highly challenging fires, such as flammable liquids and airport hangars.Operation as described above, depending on the type of system in which the foam is injected.

Water spray

"Water spray" systems are operationally identical to a deluge system, but the piping and discharge nozzle spray patterns are designed to protect a uniquely configured hazard, usually being three-dimensional components or equipment (i.e. as opposed to a deluge system, which is designed to cover the horizontal floor area of a room).The nozzles used may not be listed fire sprinklers, and are usually selected for a specific spray pattern to conform to the three-dimensional nature of the hazard (e.g. typical spray patterns being oval, fan, full circle, narrow jet).Examples of hazards protected by water spray systems are electrical transformers containing oil for cooling or turbo-generator bearings.Water spray systems can also be used externally on the surfaces of tanks containing flammable liquids or gases (such as hydrogen).Here the water spray is intended to cool the tank and its contents to prevent tank rupture/explosion (BLEVE) and fire spread.

Water mist

Water mist systems are used for special hazards applications.This type of system is typically used where water damage may be a concern, or where water supplies are limited.NFPA 750 defines water mist as a water spray with a droplet size of "less than 1000 microns at the minimum operation pressure of the discharge nozzle".The droplet size can be controlled by adjusting the discharge pressure through a nozzle of a fixed orifice size.The fire suppression mechanisms provided by water mist systems include cooling, local flame oxygen reduction, and radiation blocking.In operation, water mist systems can operate with the same functionality as deluge, wet pipe, dry pipe, or pre-action systems.The difference is that a water mist system uses a compressed gas as an atomizing medium, which is pumped through the sprinkler pipe.Instead of compressed gas, some systems use a high-pressure pump to pressurize the water so it atomizes as it exits the sprinkler nozzle.Systems can be applied using local application method or total flooding method, similar to Clean Agent Fire Protection Systems.