Making passive active
INTERVIEWED BY JAYASHREE MENDES
The use of sub-standard fire safety systems is rampant across the country.
What are some of the reasons? How can one educate developers?
Over the last five years, a staggering 23,942 incidents of fire and 57,192 other rescue calls from across the city kept the Mumbai Fire Brigade on its toes. Together, these have claimed 1,281 lives, of which over 150 were lost due to fire breakouts alone.
Effective firefighting has been hampered by the increasing vertical development of the city, denser slum pockets, cramped market places, and a perennially choked road network. It’s disheartening to note that, for a vast majority, fire safety and security is not a priority in India. I think developers need to look at this as a life and property saving measure and not as an investment. Of course, there’s a cost factor involved, which over time is worth the investment.
Fire prevention includes minimizing ignition sources, as well as educating the occupants and operators concerning operation and maintenance of fire related systems for correct function, and emergency procedures including notification for fire service response and emergency evacuation. A fire brigade carries out scrutiny of buildings in two ways — passive and active firefight-Making passive active ing — and in two stages —no objection certificate (NOC) at the time of planning and another NOC at the time of occupation.
Passive fire-safety features of a building include escape routes, fire lifts, fire-exits, refuge area and space around the building. Active firefighting features of a building include smoke detectors, alarms, riser systems, sprinkler system, functional hose-reels and a water tank.
Most of the time fire officials in today’s scenario rely heavily on external firefighting because internal firefighting systems are inadequate. Most fires can be prevented from escalating if internal fire safety systems are in place. The hose-reel pipes are supposed to throw water at a pressure of at least 3.2 kg/ sq cm if a fire has to be extinguished.
However, due to ill-maintenance of the pipes, water comes out with limited force, rendering the system useless.
How do passive fire protection (PFP) systems work in case of a fire?
PFP is a range of measures designed to prevent, contain or slow the spread of fire from the area of origin to other areas. PFP limits damage and provides time to the occupants for emergency evacuation. PFP is one of the three key components of structural fire protection in area. The other two components are active fire protection and education.
The aim of PFP is demonstrated in fire testing and involves live fire exposures upwards of 1,100°C, depending on the fire-resistance rating and duration one is after. To accomplish this, different types of materials are employed in the design and construction of systems.
PFP, despite its name, is always at work.
Based on preventing collapse through structural fire resistance, when properly installed and maintained, a building’s passive fire protection can save lives and assets, and the building itself. Measures such as fire stops, fire walls, and fire retardant coatings do not typically require electric or electronic activation or a degree of motion.
Could you explain the state-of-the-art systems used in PFP systems?
There are four main PFP methods: cavity barriers, boarding systems, fire resistant glass, and flame retardant coatings.
Cavity barriers are designed to prevent the spread of smoke and fire through walls, floors and cavities in building. This is done by installing a range of PFP products that resist the movement of smoke and fire inside spaces.
PFP via boarding systems involve encasing structural steelwork in rigid and semi-rigid boards to protect the structural integrity of steel work in the event of a fire.
Fire resistant glass uses intumescent technology that becomes viscous on temperature increase and forms a dense, heat insulating material that halts the spread of fire and chance of window blow outs.
Flame retardant coatings are of two types: fire retardant coatings of intumescent fire protection; and vermiculite fire protection.
Intumescent coatings are applied as an intermediate coat in a coating system. Because of the relatively low thickness of this intumescent coating (usually in the 350- to 700-mm range) and anti-corrosive nature, intumescent coatings are preferred for aesthetic reasons not to mention performance- wise. Intumescent fireproofing is a layer of paint applied along with the coating system on the structural steel members. The thickness of the intumescent coating is dependent on the steel section used.
In vermiculite coatings, the structural steel members are covered with vermiculite materials as a thick layer.
This is a cheaper option as compared to an intumescent one, but is aesthetically unpleasant. Moreover if the environment is corrosive in nature, then the vermiculite option is not advisable, as there is the possibility of water seeping into it (because of the porous nature of vermiculite).
In the eventuality of a fire, the steel structure will collapse once it attains the critical core temperature (around 550o C). The PFP system can delay this by creating a layer of char between the steel and fire. Depending upon the requirement, PFP systems can provide fire ratings in excess of 120 minutes. They are recommended in infrastructure projects. Intumescent coatings can be applied on a variety of substrate such as paper, fabrics, wood, leather, plastics/ SPU foams and metals.
What are the numerous materials that go to make up PFP systems?
Based on compartmentalisation of the fire to prevent collapse through structural fire resistance, when properly installed and maintained, your building’s passive fire protection can save lives and assets, and the building itself.
Interior finish: Some of the interior finish materials used are plaster, gypsum, wood and plastics.
They serve several functions. Some functions are acoustical and insulation, as well as protective against wear and abrasion. Materials that exhibit high rate of flame spread or add fuel to the fire or produce hazardous quantities of smoke and toxic gases would be undesirable.
It is observed that the injuries during any fire accident are due to inhalation of toxic fumes, suffocation, panic and stampede. Therefore selection of eco-friendly fire retardant coatings is relevant.
Explain the salient features of fire retardant coatings along with the products that fall under the series and their use in new constructions.
Because almost anything will burn, the objective of a flame retardant is to increase the resistance of a product to ignition and to reduce flame spread.
In India, Anantco offers Flamebloc technology through its tie up with Buckman Laboratories Inc, USA. They are environmentally friendly water based, non-toxic, non-allergic, non-hazardous, non-halogen based clear liquids and free of PBDE’s (Polybrominated Diphenyl Esters) or any other restricted chemicals.
Off-gassing: During the first moments of fire exposure, water vapour and carbon dioxide are released to displace oxygen from the surface so flaming cannot occur, providing time for adequate char to form and take over after the ‘off-gassing’ phase.
Temperature control: For a period of time (depending on the amount of chemical used), the protected material is maintained at a temperature of 104o C or less, due to water within the coating converting to vapour.
This chemical action will not allow the material to rise above that temperature until all the water is gone. Since ignition temperatures for cellulose is typically over 212o C, this provides a powerful resistance.
Charring: Char is formed as a barrier between the fire and the protected material, converting the outer surface of the material to non-flammable char, and/or building up layers of carbon char foam, as an insulation that continues to separate the fire from the protected material for an extended period of time.
Intumescent: The layer of carbon char continues to form and expands up to 100 times the original film thickness.
This provides an insulation and thermal barrier and the substrate is protected from the effects of the fire.
Flamebloc GS fire retardant coatings can be used for a variety of substrates, such as paper, natural and synthetic fabrics, wood, plastics and cables, FRP and even metals.
Fire regulations in India are based on National Building Codes. How product or application-specific are they?
The National Building Code of India (NBC) is an instrument providing guidelines for regulating construction activities.
It serves as a model code for adoption by all agencies involved in building construction. The code specifies the demonstration of fire zones, types of building construction according to fire resistance of the structural and non structural components and requirements necessary to minimise danger to life from fire, smoke fumes or panic before the building can be evacuated.
Absolute safety from fire is not attainable in practice. The codes specify measures that will provide that degree of safety from fire that can be reasonably achieved. A part of the revised code does cover aspects pertaining to design and construction of buildings on passive fire protection measures, also describing the various types of building materials and their fire rating.
What are some the international products/technology available in countries outside India in passive fire protection?
Fire-resistance rated walls, fire resistant glass, fire-resistance rated floors, closures (fire dampers), cable coating, fireproofing cladding (materials include perlite, vermiculite, calcium silicate, gypsum, intumescent epoxy, Durasteel), MicroTherm; enclosures or the provision of circuit integrity measures to keep electrical cables operational during an accidental fire; and passive fire protection, which includes compartmentalisation of the overall building through the use of fireresistance rated walls and floors.