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| 03 July 2008 | |||||
FIRE PROTECTION SYSTEMS FOR
HIGH RISE BUILDINGS
Due to scarcity of land in urban areas, the trends of high rise buildings in the form of apartments, shopping complexes, hotels, industrial and institutional buildings, underground and multistory parking towers, intelligent buildings, railway stations linked with tunnels, stadiums and museums etc. are increasing day by day. The buildings having height more than 15 meters come under the category of high rise buildings. Such buildings are more prone to fire disasters. The proprietors of such buildings have the liability to construct such buildings in accordance of fire protection norms stipulated in the National Building Code of India 1983. Such buildings are required to be constructed in such a way so that no part of any building should remain 30 meters away from the staircases proposed in the building blocks. If building blocks are supported by the water sprinklers, then the said distance from the staircase may be kept as 45 meters. At least, 6 meters wide open spaces are required to be kept open around the building blocks for free movement of the fire tenders. In addition, provision of lifts is necessary for buildings having more then 4 storey buildings. The building plans of such buildings are required to be approved from the concerned District Fire Officer. The proprietor of the building has to install fire detection and suppression system, water sprinkler system in the building as per National Building Code Of India, 1983.
Sprinkler Systems Sprinkler systems are the oldest and most widely used type of automatic fire extinguishing systems. When an unforeseen fire starts, these systems immediately and automatically generate a fire alarm and extinguish the fire.
1. Wet Sprinkler Systems
The pipes are kept filled with pressurized water in order to spray out water as soon as the sprinkler heads open, so this is the most widely used type of system. The configuration of this system are described as below.
2. Dry Sprinkler System
The dry system water flow detection unit is filled with pressurized water up to the primary side, and the secondary side piping is filled with pressurized air, so when the air pressure in the secondary side drops when a sprinkler head opens, the dry system water flow detection unit opens to release the water. This type of system is used in frigid areas where there is a danger that the pressurized water in the dry system water flow detection unit secondary side piping could freeze. The basic system configuration of this system is described as under. 3. Pre-operation Sprinkler System
The water flow detector unit's primary side is filled with pressurized water and the secondary side piping is filled with compressed air. When a fire occurs, the fire detector uses the fire signal it has caught to first open the pre-operation water flow detector unit to cause the primary side pressurized water to flow to the secondary side. This pressurized water operates the pressure switch, which generates a fire alarm, and the decrease in pressure in the primary side piping causes the pump to operate and begin spraying water when a sprinkler head is opened by a heat sensor. The characteristic of this device is that water will not be sprayed unless both the fire detector and a sprinkler head operate to prevent water from accidentally being sprayed and causes water damage when there is no fire. The configuration of this system is described in the following
4. Open Sprinkler System
5. Foam Fire Extinguishing Systems Foam fire extinguishing systems are installed based on the technical standards of the Fire Service Law, etc., and are used to protect parking areas, automobile service garages, airplane hangers, semi-hazardous materials, special flammable materials storage areas, handling areas, etc. Foam fire extinguishing systems are fire extinguishing systems that automatically opens all the foam heads in batch, starts up the fire extinguishing pump, and sprays the fire extinguishing agent when a fire is detected by a sensor head installed in the protected area. 3% fire extinguishing agent is mixed with the force fed fire extinguishing water from the fire extinguishing pump to generate a large amount of fire extinguishing foam from the foam heads. This foam covers the surface of the burning material and extinguishes the fire using the cooling effect of the moisture in the foam and the synergistic effects of cutting off the oxygen supply to and sealing off the burning materials provided by the foam covering. In addition, both wet and dry type systems can be used depending on the local conditions.
6. Powder Fire Extinguishing Systems
Powder fire extinguishing systems extinguish fires faster and more effectively than other chemical fire extinguishing agents.
The fire extinguishing principles of powder fire extinguishing agents are the suffocation, cooling action, and combustion chain reaction prohibition of the carbon dioxide and water generated by the decomposition of the agent due to the compound actions of the negative catalys. The powder fire extinguishing system consists of a powder container, pressurized container (N2 gas), set pressure operation valve, powder discharge valve, spray heads, startup unit, operation unit, and the piping and wiring that connect them. The system types are largely divided into a fixed type that uses piping to hold the heads in a fixed position, and a mobile type that uses nozzles and hoses.  By
B.N. Sharma
Retd. Senior Town Planner of
Haryana Government
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