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dimanche 2 novembre 2014

Abcs Of Fire Sprinkler Hydraulic Calculations

By Young Lindsay


Many types of sprinklers that can be classified according to its activation temperature, fast opening, orifice size of sprinkler discharge or flow rate, type of fuse element, jet application form, coverage area waterjet among many other factors involved in risk analysis and project design by the specialist (fire sprinkler hydraulic calculations).

Automatic sprinklers have an outlet for releasing water, a firing mechanism and a deflector to convert the output stream in a spray of water in area where there is fire. The trigger sprayer can be done by two mechanisms: a thermo-sensitive element or a flame detector. In this type of sprayer, the jet has a stopper that prevents the leakage of water and a stopper device releasing the trigger mechanism in this case is a device for releasing the plug.

It consists of a thermo-sensitive element that is designed to destroy at predetermined temperatures, automatically causing the release of plug and the outlet of a water spray, which should extinguish the flame right in area where it has started. This device can be of two types: side of a disassembled sprayer without bulb or fuse Vista.

The spray outlet is somewhat less sharp slope of the teeth to its plane and a little more in diameter; glass valve polished, chamfered and sprinklers have higher gate outlet. For some time, some of the sprinklers manufacturers to reduce the cost structure used as a sealant rubber gasket. Thus it was not taken into account that over time the elastic properties of rubber deteriorates, and can result in loss of containment. But the worst thing that can happen to the adhesion of rubber sealing surfaces.

Thermo-sensitive bulb. The most common sprinkler glass bulb holds the cap in place and containing therein a liquid that does not fill the bulb, leaving a gap. When heat from a fire acts on bulb, the liquid boils and vapor pressure breaks the glass stopper and then releases the pressurized water contained pipe network, download and poured over the baffle forming a jet sprayed water mist.

According to statistics in case of activated fire sprinkler-systems 40% of the time the fire was extinguished by sprinklers, 80% of flames is extinguished when triggered no more than 10 sprinklers. On this basis, taking into account the area, protected by a single sprinkler (12 square meters is determined by the area, which is needed to irrigate the maximum flow of water sprinkler-system. For the first group space area is 120 square meters.

Fire-extinguishing system is maintained in working order. Sprinklers should be regularly inspected for mechanical damage, corrosion, coating damage, obstructions irrigation. Damaged sprinklers must be replaced. Even small leaks require immediate replacement of the sprinkler. To do this, have an arsenal of spare sprinklers and constantly replenish it. Sprinkler who have been exposed to heat of combustion products exceeds the value of maximum allowable operating temperature must be replaced.

First installation started in late XIX century, after the Englishman Stuart Harrison in 1864, has developed a sprinklers. Further development of sprinkler systems associated with the names of Americans Henry Parmelee and Frederick Grinnell. By 1882 in the United States for 200 enterprises was established about 200 thousand. Sprinkler-design Parmelee. During the same year in England the first such installation was witnessed.




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