BSEE
rom the moment our ancestors discovered fire and began using it to heat and light buildings, controlling smoke and extracting it in the most efficient way became a common goal.
F Smoke ventilation
David Mowa, chairman of the Smoke Control Associaon (SCA), charts the history of smoke control and idenfies some of the catalysts for change
The original concept of smoke control took on board the process of hot air rising and the action of an internal house fireplace and chimney where smoke would be drawn upwards and out of the chimney pot through natural buoyancy. This ultimately led to the passive vent systems in use today which utilise automatic louvres or ventilator openings to allow smoke to escape by natural methods, achieved through the creation of a through flow ventilation system comprising of extract at high level and inlet air at low level which replaces the air being consumed and entrained by the rising smoke plume and fire.
The introduction of smoke ventilation can be traced back to early theatre fires in the 1880s and through to the early 1900s. A number of disastrous fires occurred, resulting in a large number of fatalities as people enjoyed the theatre show, unaware that a fire was raging out of control. This led to the introduction of legislation demanding a fire curtain at the front of the stage and also a requirement to install natural ventilation above the stage to allow smoke to escape.
Although rudimentary extractors had been deployed successfully in the years leading up to the Second World War, their use skyrocketed during the blackouts where they were needed to ventilate rooms in towns and cities on lockdown. In the 1950s there were a number of large and disastrous industrial fires in both the USA and UK and these included fires at General Motors in Michigan where a 140,000m2 plant was totally destroyed by fire and the UK had similar large fires at Jaguar Cars and Vauxhall Motors. It was noted by the firefighters that once the roof started to collapse and openings were formed the fire and smoke ventilated and this significantly improved conditions for firefighting purposes as the smoke and heat was allowed to escape.
Essentially, this was the foundation for smoke ventilation systems as we know them today. The introduction of fusible links on natural ventilators allowed them to open in a fire situation and this eventually led to automatic operation, initially controlled by compressed air and more recently by electric motors. Activation was often by linking to a fire detection system or fire alarm or by activation by the firefighters on arrival at a dedicated firefighter’s panel.
Technological advancements
Over time, improvements in our understanding, alongside technological advancements, have resulted in innovative smoke control solutions, both natural and mechanical, being put in place to save lives in an emergency situation.
By the late seventies, in buildings where passive vents were not practical, mechanical means of smoke control were being widely employed. Using high temperate smoke extract fans to force smoke out of the building resulted in clearer escape routes and improved access to fires by the fire brigade. By this point building heights, both residential and commercial, were increasing rapidly and it was also recognised that tunnels and car parks needed appropriate fire safety systems.
Association formation
Over the next 10 years, smoke ventilation and control became a growth industry around the world and in 1987 the Smoke Ventilation Association was formed in order to better protect UK interests in this fast- developing field. At this moment in time Germany and France had taken a lead in developing standards and a single industry body was needed to drive the UK industry forwards and promote the commercial interest of smoke ventilation manufacturers. The association’s priority during the first eight years was to produce technical specifications and guidance documents. Following publication, it worked through the FSH technical committees at BSI to get the specification adopted as ENs. Several of the SCA guidance documents are still used today and often referred to by system designers. The UK now frequently leads the way on smoke control principles and design methods. During the 1980s, mechanical tests were only performed on the electric motor and not the complete fan system. Following the 1999 Mount Blanc tunnel fire, it was recognised that it’s not just the motor that needs to pass a fire test, but also the impeller and wiring. This was then followed up with silencers, T-boxes and AV mounts - in fact anything that was part of a smoke control fan system, thereby giving better security of the complete assembled products working in emergency situations. By the turn of the century, computational fluid dynamics (CFD) was frequently used in the design of
buildings and smoke control systems which resulted a better understanding of how smoke reacts within different building designs and led to more sophisticated control and activation methods. In 2000, the association decided that it should change its name to the Smoke Control Association to reflect more accurately the control aspects as well as the ventilation aspects.
Industry standards
Over the last 20 years we have seen the introduction of key industry standards, including the BS EN12101 compendium of standards, BS 9991 and BS 9999. These document the maintenance requirements for both natural and powered smoke control systems, advising that life-critical equipment should be included in a building services maintenance schedule, as well as ensuring that all smoke ventilation products should be independently tested and certified by a recognised test house. In addition, BS 7346 Part 8 sets out the recognised code of practice for commissioning and acceptance testing of a smoke control system. Further tightening of existing legislation is expected to be just around the corner as we await the announcement of changes to Approved Document B of the Building Regulations.
With the SCA at the forefront, the smoke control industry of today is making great strides in raising levels of competency across the board, bringing in independent testing of products with clearer guidance of system installation. Schemes such as the IFC SDI 19 Certification (mandatory for SCA members involved in installation) have been developed to ensure a suitable level of expertise in relation to fire strategy verification, system design and the installation of smoke control systems.
As understanding, awareness and technology continues to improve, smoke control systems will be increasingly used as part of a wider fire engineering strategy within high rise buildings, playing a vital role in saving lives and protecting property for generations to come.
www.feta.co.uk/associations/hevac/specialist-groups/smoke-control-association 10 BUILDING SERVICES & ENVIRONMENTAL ENGINEER OCTOBER 2019 Read the latest at:
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uImprovements in our understanding, alongside technological advancements, have resulted in innovave smoke control soluons
BSEE 40th ANNIVERSARY ISSUE The evolution of smoke control
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The
introducon of smoke venlaon can be traced back to early theatre fires in the 1880s and through to the early 1900s
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