FIRE SAFETY IN HAZARDOUS BUILDINGS (GROUP J CATEGORY)
As per the NBC (National building code) 2016, hazardous buildings are classified under GROUP J category, these category buildings include.
a. Buildings in which storage, handling, manufacture or processing of highly combustible, explosive materials or products which tend to burn with extreme rapidity and produce poisonous fumes or explosions like highly flammable liquids, liquefiable gases like LPG, rocket propellants etc
b. Buildings in which storage, handling, manufacture or processing of highly corrosive and toxic chemicals like acids, alkalis and other organic solvents which tend to produce corrosive, poisonous gases like chlorine phosgene, sulphur dioxide etc when stored under pressure and in quantities exceeding 70 m3
c. Buildings in which storage, handling, manufacture or processing of explosive mixtures of dust which results in spontaneous explosions due to fine nature of dust like artificial flowers, synthetic leather, ammunition, explosives and fireworks.
FIRE SAFETY REQUIREMENTS FOR “J” CATEGORY BUILDINGS:
These category buildings come under “FIRE ZONE 3”, hence certain fire safety requirements are to be followed like
1) Automatic sprinkler systems: All high hazard industrial occupancies should be having automatic sprinkler protection or any other protection required for that particular hazard, designed to minimise danger to occupants in case of fire or other emergencies before they have time to utilize exits to escape.
2) Exits: From every point in every floor area, there should be at least two exits accessible in different directions, if rooms are present then there should be two exits accessible in different directions in that rook.
3) Fire detection system: All high hazard industrial occupancies should have vapour/flame/ ember/spark detectors and explosion suppression systems depending on the type of fire hazard involved.
4) Gas Safety: Each building where gas is employed for any purpose shall be provided with an approved outside gas shutoff valve conspicuously marked.
5) Heating plant: Each boiler room or room containing a heating plant should be separated from the rest of the building by a separating wall also rooms containing high-pressure boilers, refrigerating machinery, transformers or other service equipment subject to possible explosion shall not be located directly under or adjacent to exits. All such rooms should be cut-off from other parts of the building and shall be provided with adequate vents to the outside air.
6) Flameproof enclosure: Devices which generate a spark or glow flame capable of igniting flammable substances should be enclosed in a flameproof enclosure, flammable substances generate a lot of vapour, which catch fire easily, hence proper flameproof enclosures should be installed where ever required.
7) Restricted chemicals: The usage, handling, storage and sale of gasoline, fuel oil and other flammable liquids shall not be permitted in “Group J” occupancies unless such use, handling, storage and sale is as per appropriate legislation in force.
8) Vents: All openings in exterior walls except wall vents shall be protected by a fire stop assembly and they shall be fixed, automatic or self-closing.
9) Automatic fire extinguishing system: When a machine requires cleaning with flammable liquid, it should be provided with an adequate system such that an agent is automatically released to the machine whenever an explosion occurs due to tendency of the flammable liquid to catch fire. This is so more in dry-cleaning establishments.
10) Dust collection and exhaust system: Adequate dust collecting and exhaust system to be provided for all kinds of machinery and equipment which generates or emits combustible or explosive dust and the potential to ignite, the exhaust ducting system should be provided with spark detector and arrest system. Hazardous buildings shall have vapour/flame/ ember/spark detectors and explosion suppression systems depending on the type of fire hazard involved.
GENERAL PARAMETERS REQUIRED FOR “J” CATEGORY BUILDINGS:
1) OCCUPANT LOAD: It is the Maximum number of persons that might occupy a building or portion thereof at any one time. The occupant load factor in “J” category buildings is 10(m2/Person).
2) HEIGHT OF BUILDINGS: Buildings above 15-meter height cannot be permitted under “GROUP J CATEGORY”
MINIMUM REQUIREMENTS FOR FIRE FIGHTING IN “J” CATEGORY BUILDINGS:
· Fire extinguisher: It is a portable device which is also called as first-aid fire extinguisher which discharges water, foam, gas or other materials to extinguish the fire.
· First aid hose reel: It is a piece of equipment consisting of the reel, water inlet pipe, shut off nozzle, stop valve with hose reel tubing to provide the most effective firefighting facility.
· Wet riser: It is an arrangement for firefighting within the building by means of vertical rising mains not less than 100 mm nominal diameter with landing valves on each floor/landing for firefighting purposes and permanently charged with water from a pressurized supply.
· Down comer : (not required up to 15 meters height and if it is a single storey building): It is an arrangement of firefighting within the building by means of down-comer pipe connected to terrace tank through terrace pump, gate valve and a non-return valve and having mains not less than 100 mm internal diameter with landing valves on each floor/landing. It is also fitted with inlet connections at ground level for charging with water by pumping from fire service appliances and air release valve at roof level to release trapped air inside.
· Yard hydrant: This is a distribution system connected to a water supply system for firefighting and which is having a network of piping installed underground or aboveground around through inside of a building with internal and external hydrants fitted with landing valves at regular intervals according to the occupancy.
· Automatic sprinkler system: This is an automatic fire suppression system that uses water as the main firefighting media. It is a system of water pipes fitted with sprinkler heads at suitable intervals and heights and designed to actuate automatically, control and extinguish a fire by the discharge of water at pressure.
· Automatic Detection and alarm system: A system comprising components and sub-systems required for automatically detecting smoke, heat or fire initiating an alarm and other actions as appropriate. This system also includes a manually operated electronic fire alarm system (MOEFA)
The underground static water storage tank combined capacity for wet riser, yard hydrant and sprinklers set of pumps should be so designed that during firefighting the minimum requirement of 240 minutes minimum supply of uninterrupted water should be met.
Article by PJ Mohan
Sr. Faculty, NIFS
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