Wednesday 5 November 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.

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.

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.

Sprinkler is a component of fire-fighting system, irrigation head mounted in sprinkler installation (network of water pipes, which is always water or air under pressure). The spray outlet closed heat or thermo-sensitive bulb lock having a temperature of up to 343 degrees C. Upon reaching room temperature a certain value, locking the system soldered or bursts flask, and water begins to irrigate the protected zone. The disadvantage of such a system is relatively large inertia - head opened after about 2-3 minutes after the temperature rise.

The response time of these systems shall not exceed 300 seconds for low-temperature sprinklers (57 and 68 degrees C) and 600 seconds for the highest-temperature sprinklers. In 1806, an automatic fire extinguishing installation was patented by Englishman John Carey. He proposed to build in the protected area network of pipelines from the water head tank, and on the network to install sprinklers with small holes.

Another way to activate a sprinkler is associated with flame detector which opens the closed spray, which in this case is a solenoid valve (solenoid valve) when a flame occurs in area protected by the sprinkler. The advantage of this system is that, once the blaze is out, the water outlet is cut and, if reignite, reopens. With the system of sensitive element, it would take someone off the water supply or water damage could exceed those caused by the inferno.

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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