[pull_quote_center]Passive fire protection consists of non-mechanical, but stationary systems built, bolted or coated to a building, to contain the swift spread of fire, thus securing valuable time to save lives and valuable structures.[/pull_quote_center]
Cable trays, which power a building, generally spread horizontally above ceilings, up through floor slabs and then again out, around, and above the ceilings of the floor above.These can be likened to veins which carry blood throughout the human body.
Should a fire start at any point in this network of cables, it generally runs very fast above the ceilings and then vertically through cable ducts to the top of the building and on every floor. Very quickly, burning material starts setting the ceilings themselves alight.
The burning material then falls onto the carpets, curtains and furniture below and, well, there is your typical high rise fire! Given that fire spreads above ceilings and up hidden ducts, it can be well established before it is discovered.
Passive Fire Protection
Traditionally, fire protection for buildings has relied almost exclusively on passive fire protection. Passive fire protection consists of non-mechanical, but stationary systems built, bolted or coated to a building, to contain the swift spread of fire, thus securing valuable time to save lives and valuable structures.
With the advent of active fire protection systems however, the importance of passive systems for reducing smoke and fire spread through compartmentalization has slowly diminished. In fact, active fire protection features are being used more and more in lieu of non-combustible fire resistive construction.
Designers are reducing or trading off the amount of passive fire protection in buildings by implementing additional active features. Still, passive systems remain essential in minimizing damage to one’s property enabling use of a structure even after a fire.
We look at one way of fireproofing passively – fireproof coatings.
Fireproof Coatings
Fire retardant coatings insulate a surface from heat by expanding to form a tough char barrier which fire cannot penetrate; deprived of fuel, the fire quickly dies.
Alternatively, the char barrier reacts to form a thermal barrier that reduces the temperature increase on structural steel either avoiding or delaying the time it takes for the steel to heat up to the point that it loses structural integrity.
Fire proof paints are formulated to release a flame extinguishing gas on contact with fire. They assist in the control of fire hazards caused by combustible materials, such as wood and derivative construction materials.
They can be used either as a decorative finish over intumescent coatings or used on their own for a decorative topcoat that is deemed to provide adequate fire protection. These paints are also suitable for use directly on bare surfaces or on sound previously painted non-combustible walls and ceilings.
Hybrid Inorganic Polymer System (HIPS)
The Hybrid inorganic polymer system (HIPS) is a fairly new fire resistant coating material that can withstand temperatures of up to 1000 degrees centigrade unlike commercial coatings – used on building materials and structures – which breakdown at 150 to 250 degrees centigrade.
HIPS coatings contain an inorganic geopolymer resin and a small component of polymer additives. Geopolymers, an emerging class of ceramic like inorganic polymers produced at room temperature, are fire blast and acid resistant.
They are cost effective and made from readily available raw materials; they can be derived from industrial by-products such as fly ash and blast furnace slag.
Geopolymers can also be cheaper than organic resins and can be coloured with pigments or dyes. The polymer additives in HIPS improve flexibility and waterproofing properties and provide for stronger adhesion, an important property for any coating.
Applications of HIPS
Adhesive and Coatings
In adhesive and coating applications HIPS is applied to the surface of one or more substrates and cured by elevated temperature or a combination of pressure and elevated temperature.
HIPS cures from ambient temperature to below 90 degrees centigrade. HIPS may be used to produce laminates and plywoods, and to bond a variety of materials together. The HIPS may be applied as a coating on, for example, timber, timber-based products and metals such as structured or galvanized steel.
When wood is exposed to a naked flame volatile and combustible substances present in the wood are released and these contribute to flame ignition and propagation.
This results in a rapid and significant release of heat. However, when the wood is coated with an hybrid inorganic polymer, release of volatile substances in the wood is inhibited with the result that flame propagation (and thus burning of the wood) is reduced.
In other words, the hybrid inorganic polymer is believed to seal in the wood those volatile substances that contribute to (fuel) flame propagation.
It is also believed that the HIPS coating may provide intumescent properties derived from the inorganic polymer backbone structure which both insulates timber and suppresses flammability.
The composition of HIPS to be used to coat wood must have a suitable viscosity. If the composition is too viscous there will be minimal penetration of the surface of the wood.
Some penetration is needed to achieve a good bond. If the composition is too thin (not viscous enough), it may not be possible to form a suitably thick layer on the wood surface (although this may be remedied by the application of multiple coatings).
In practice the viscosity of the composition should typically be of the order of 1500-2000 centipoise at room temperature.
The viscosity of the coating may also influence the way in which the composition is applied to the wood. A variety of techniques may be possible here including brushing and spraying of the composition onto the wood, and dipping of the wood into a reservoir of the composition.
Another useful application of the HIPS is the manufacture of wooden furniture. Conventionally, the joints in furniture may be bonded using phenolics adhesive.
However, these tend to be expensive and have a high volatiles content leading to safety implications. In contrast, HIPS resins may be employed with similar or even superior bonding performance and with associated benefits of reduced cost and reduced volatiles content.
In fireproofing structural steel, HIPS allows it to maintain its integrity long enough for people to evacuate a building and allows the building to remain firm and standing long enough for a fire department to put the fire out.
HIPS coatings will be free of volatile organic compounds, will not burn or produce heat and will not release smoke or toxic chemicals at temperatures of up to 1200 degrees centigrade.
Bindings
When used as a binder the HIPS components are blended with a functional additive, which may be a powder, granule or fibrous material, shaped and then cured by the action of heat, or a combination of heat and pressure, to form a monolithic product.
During curing, co-condensation reactions result in formation of a thermally stable composite product. The thermal stability of such composite products may be enhanced by inclusion of functional additives that have good high temperature stability (oxidation resistance). Such additives include natural fibres and graphite, for example.
The nature of the functional additive and the proportion included in the composite will dictate the end use of the composite. Typical uses of such composites include automotive, rail, marine and aviation products such as brake and clutch components, engine moulds, tyres and lining materials (such as vehicle cockpit linings, parcel shelves etc).
Such linings typically use paper or natural or synthetic materials (e.g. cotton, glass) in fibre or yarn form, as the additive.
The HIPS may also be used to form foundry moulds for high temperature casting applications. The strength of HIPS materials is comparable with that of phenolic resins in heat sensitive applications. HIPS however retains higher strength at higher temperatures. Its formulations are tailored to be interchangeable with phenolic resins and have higher fatigue resistance than normal phenolics.
HIPS technology exhibits potential where the manufacture of fireproof wood composites and fire seals is concerned promising to revolutionize the fire proofing industry.
HybridSil™
Nanosonic’s HybridSil™ is a new coating technology that provides fire, blast and ballistic protection to various types of structures from ships to buildings. The unique property of the coating is its ability to combine flame and blast protection.
A handful of materials provide either feature but not both since the properties are mutually exclusive with currently available material technologies. Commercial applications for the flame and blast resistant material include safer, protective coatings for buildings and vehicles.
Other future uses could include furniture and clothing manufacturing industries. The material may be tailored for 20 to 60 minutes at room temperature followed by curing within 24 hours in shipyard environments. It can be incorporated into a product such as a ship’s hull in several ways, including painting or using an airless spray technique.
The product was developed in response to the U.S. Navy’s request for better blast protection of its military fleet without the concerns of flammability and smoke toxicity that challenge current products. HybridSil™ has also been named as one of the 100 most technologically significant products introduced worldwide during the past year by American Research and Development (R&D) magazine.
Albi Clad 800
Albi Manufacturing’s Albi Clad 800 intumescent coating is applied to protect both internal and external structural steel, concrete and other construction materials from fire. Its superior resistance to weathering and abuse makes it the universal material for severe environments.
Albi Clad 800 is UL classified for one to three hour protection under E-119 and UL 1709 High Rise, Hydrocarbon fire test criteria. Other beneficial properties of Albi Clad 800 include its lightweight, hammer-hard, thinfilm application that follows the contour of substrate, outstanding wear resistance, its ability to eliminate dusting, flaking, cracking and delamination and its outstanding fire protection even after years of extreme exterior weathering, abuse and vibration.
This coating also has high resistance to ultraviolet exposure, has asbestos-free formulation and comes as single-component, factory formulated to eliminate job-site blending not to mention its aesthetic, architectural finish. It has been approved by major building codes and insurance underwriters.
List of Contributors:
Contego Fire Barrier Solutions
Alan Lancaster Email [email protected]
Website: www.contegofirebarrier.com
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Dr Dilip Manuel
Business Development Manager
Email: [email protected]
Website: www.csiro.au
NanoSonic
Lynn Nystrom
Director of Communication
Email: [email protected]
Website: www.nanosonic.com
Active Fire
Jeffrey Brown
Email: [email protected]
Website: www.activefireprojects.com
Xtinguish
Maxwell Okello
General Manager
Email: [email protected]
Website:www.xtinguish.co.ke
