The LWF Blog
Facilities Management & Fire Safety – Smoke Control – Part 6November 9, 2017 2:58 pm
In LWF’s Fire Safety blog series for those who work in Facilities Management or who have an interest in fire safety, we have been looking at smoke control and how it is used in a building. In Part 5, we discussed how ventilation in lobbies and stairways is used by fire-fighters to extract smoke. In Part 6, we will continue to discuss ventilation and the uses to which it can be put.
When considering large single-storey premises, such as warehouses, smoke ventilation is of use to the fire service as it will aid in keeping the smoke layer at a height which will allow reasonable visibility at head height and below. In some areas of England and Wales, this is a requirement, however it is advisable even in those areas where it is not.
Most commonly, a warehouse ventilation system will be one where vents have a fusible link which, upon melting as the heat rises from a fire, automatically opens the vent. There are other types including vents which become operational when a smoke detection system is activated, or indeed, by manual controls.
While powered extraction vents are available, they require a more complex installation, including fire protected wiring, reliable power source (in case the power is affected by a fire) and fans able to withstand high temperatures. The advantage to such a system over natural ventilation is that it is less vulnerable to external wind pressures.
While the provision of smoke extraction in a warehouse is intended for use post-evacuation, for the fire service, both natural and powered extraction can be found elsewhere and for other applications. Enclosed shopping centres, for instance, or large supermarket superstores might also employ such systems to maintain a smoke free area at head height and below to aid the evacuation of those areas in a fire situation.
Indeed, such systems are most useful to aid evacuation in those buildings where normal travel distances cannot be adhered to and a fire engineered solution has been employed.
Another area where smoke extraction may be used is that of atrium buildings. A system may be installed to aid evacuation, where appropriate, but more commonly it is in use for the use of the fire service. Specific guidance on smoke control and fire control measures in atriums can be found in BS 9999:2017 – Fire safety in the design, management and use of buildings – Code of practice.
While smoke ventilation can be a most useful tool either to aid evacuation or the fire service, it is only really possible when the fire size is known and controlled. Therefore, sprinkler systems are commonly installed to provide fire control. This means that the fire size can be reliably predicted and the rate of smoke extraction accurately calculated.
The next blog from LWF will be Fire & Rescue Service Facilities – Part 1. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact Peter Gyere in the first instance on 0208 668 8663.
Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 25 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.