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Drainage innovations provide built-in fire and smoke protection

20 Sep 11 Peter Jennings, Technical Director for ACO Building Drainage, looks at how poor planning of drainage systems can contribute directly to the spread of fire in large buildings.

Drainage systems, by their very nature, are fundamentally open systems that safely remove water and liquid wastes away from the inside and outside of commercial and public buildings. However, it is the intrinsically open construction of these channels and gullies that presents a significant problem when in comes to fire protection. This is especially true within buildings and closed spaces, as drainage channels between floors can provide an unobstructed, open passage through which flames, smoke and toxic gases can easily travel from room to room and floor to floor at an alarming rate in the event of a fire. Worse still, the relatively narrow aperture of a drainage channel can actually cause a venturi effect and dangerously increase the speed at which flames and fumes are sucked or blown through and therefore spread.

Indeed, in recent years there have been a number of high profile disasters where public and commercial buildings have been destroyed and lives lost as a direct result of fire and fumes spreading rapidly via conduits and drainage systems. Take for example, the devastating and tragic fire that killed 17 people, mostly due to smoke inhalation, and left over 100 injured at Düsseldorf Airport in Germany on 11th April 1996.

The fire was caused when hot glowing particles from a welding operation dropped onto a part of the roof of terminal A where PVC cables and insulation materials immediately caught fire. As a result, flames, smoke and noxious fumes then broke into the cable ducts and drainage gullies and spread throughout the entire occupied building. On top of the loss of life and casualties, the fire caused hundreds of millions of euros’ worth of damage to the airport, making it, at the time, the biggest public disaster in the history of North Rhine Westphalia.

Critically, the key problem here was caused by the use of PVC, which is extremely flammable and generates huge volumes of toxic gases. However, the point remains that the ducts and gullies running between the floors offered an unobstructed route for flames and fumes to be sucked or blown through.

In the wake of the much publicised tragedy, the building was completely modernised and, most importantly, all the PVC was replaced with alternative materials. The fire also raised public awareness of how a building’s drainage system can cause the problems of a fire to escalate rapidly, ultimately with catastrophic effects. Accordingly, the danger is now widely recognised in Germany and standards have been introduced that make it vital for appropriate gully protection systems to be installed in public buildings, such as hotels and offices.

Although the problem is understood in Germany, in other European countries, including the UK, the dangers are still yet to be fully appreciated. In addition, even though standards have been introduced in recent years to provide design guidance for minimising the risk of flames, smoke and fumes, such as the Regulatory Reform (Fire Safety Order) 2005, Building Regulations Approved Document B Fire Safety, April 2007, BS EN 1366-3:2004 Fire Resistance Tests for Service Installations and BS EN 13501-2:2003 Fire Classification of construction products and building elements, the task of specifying the correct building drainage remains somewhat complex as there is still a lack of widely recognised and appropriate universal standards for companies to work to. This lack of guidance and understanding means that many specifiers are still relying on traditional technologies, such as sprinklers or fire barriers, to prevent the spread of flames and fumes, particularly in older buildings.

Nonetheless, the design and installation of drainage systems is one area that requires considerable thought, particularly when you consider the dire consequences of not doing so. In order to address this issue, some leading manufacturers, such as s ACO Building Drainage, have been working to develop a new generation of innovative technologies, including a series of revolutionary high performance floor gullies that are essentially fire proof and, perhaps most importantly, provide an unparalleled degree of automatic smoke protection. Equally, this leaves contractors rest assured that these systems provide high performance fire protection and meet the associated standards, without compromising the ability to carry out their primary task of water removal.

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Traditionally, drainage products have generally been manufactured using plastic and aluminium, which makes them unable to withstand the high temperatures of up to 1,000°C that are often found in building fires. By comparison, the latest gullies are manufactured with cast iron bodies with a melting temperature of at least 1,120°C. Equally, to prevent the drainage gullies and connecting pipework from providing a path for the passage of fire, smoke or noxious gases, these gullies feature unique fire protection cartridges.

Perhaps most importantly, the latest high performance cartridges are tested and certified to meet BS EN 1366 Part 3 – Fire Resistance Tests for Service Installations – Penetration Seals with up to two hours protection, and are constructed from an intumescent material that expands dramatically when the ambient temperature reaches approximately 200°C. As a result, the rigid cast iron body forces the cartridge to expand inwards causing it to block off the gully outlet entirely from fire and smoke. Furthermore, the fire protection cartridge can easily be retrofitted if the building undergoes a change of use, where fire protection is later required.

In addition, this latest generation of drainage gullies has been designed in accordance with BS EN 1253 Gullies for Buildings meaning that they can be installed without the need for further performance and safety testing. Moreover, they offer specifiers a broad range of grating styles, in either stainless steel or copper alloy for use in solid or suspended concrete floors, and in both new build or refurbishment projects. They are also compatible with a wide range of floor coverings, including tiled, resin, cementitious or flexible sheet flooring applications.

The latest building drainage systems have also been designed to improve the flexibility and ease of use for specifiers and installers still further, making them ideal for multipurpose applications and allowing for easy installation with modern building and construction techniques.

Some of the leading manufacturers, such as ACO Building Drainage, are members of the Association for Specialist Fire Protection (ASFP) and their fire protection drainage systems can be found in the ASFP Red Book, which is the definitive guide to the provision of proprietary materials and systems used for fire stopping and sealing of penetrations to comply with building regulations.

Recent high profile disasters, coupled with the fact that 2008 saw the highest UK peacetime fire losses of all time, has helped to raise awareness of the importance of correctly specified and fitted fire proof drainage systems in order to protect not only public and commercial buildings from damage, but most critically, people. Thanks to the introduction of the new generation of fire resistant gullies, designers and installers can now rest assured that optimum protection against flames, smoke and poisonous gases, as well as effective water removal will be achieved at all times, maximising safety, comfort and customer satisfaction over a long service life.

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