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.

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.

Therefore, in case of fire, after the destruction of temperature sensor, the lid remains tightly spray glued to the hull and the water from the system is not received. Such cases were reported in the fire at many places in USA. After that, the producers was conducted large-scale action to recall and replace all sprinklers with rubber sealing rings. In some countries the use of sprinklers with a rubber seal is prohibited.

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.

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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