Wednesday, 29 October 2014

Guide To Fire Sprinkler Hydraulic Calculations

By Young Lindsay


Water-sprinkler systems appeared during the end of XIX century. Favorable results of protection forced inventors to pay serious attention to this kind of firefighting. Before the revolution of liability insurance, companies recognized the impact of fire sprinkler hydraulic calculations in factories to reduce losses.

In 1902 Frederick Grinnell patented the design Grinel alarm check valve. Water system Grinnell. A - short tube diameter of half an inch, screwed into a water pipe and closes flat bottom valve b; valve lever is held and backup c d. Backup d attached to the copper arc e apparatus with a weak solder which melts at a temperature of 73 degrees C.

There are other automatic, instead of the capsule are connected to a fire detector which sends an automatic valve that opens when the detector knows of a fire. When quenched, the switch closes the valve and, if applicable, would open again if the fire is revived. Systems differ from sprinklers sprayed water on the element that disperses the water these last is a mouthpiece designed to offer an angle of fog.

Fuse trip. The plug is held in position by a mechanism formed by two metal plates joined with a weld, with a melting point of carefully calibrated. In a blaze, the heat generated softens the solder, causing the water pressure acting on the cap and then disarm the system to skip the plug, allowing the escape of liquid. The water goes through the hole and strikes against a sheet, designed to distribute the jet way to rain (deflector). Each spray has its own fuse, so that only those sprinklers that are in zone of influence of trigger.

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.

These processes may take more or less depending on rate of release of surrounding heat to spray, the distance between the sprinkler and ceiling, the distance between the spray and the floor, the roof slope and other factors that have been extensively studied by the NFPA (National Fire Protection Association), UL (Underwriters Laboratories), FM (Factory Mutual), among other research and development in flame protection systems.

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.

Triggered sprinkler repair and re-use are not subject. They must be replaced with new sprinklers. Temperature rating of sprinklers can be identified by the color of bulb. Before replacing the installed sprinkler-fire extinguishing system must be disconnected completely relieve pressure in piping, drain systems for wet or dry pipe bled for. Followed to dismantle the old sprinklers and install a new one, making sure that its design, temperature and operating time correspond to those indicated in project. After replacing the sprinklers should be installed fire-extinguishing system in standby mode.




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