The LWF Blog
Facilities Management & Fire Safety – Fire Extinguishing Equipment – Part 7
February 15, 2017 11:02 amIn this blog series for those who work in Facilities Management and have an interest in or responsibility for Fire Safety, we have been looking at the different types of fire extinguisher and their uses. In the last few issues, we have covered the most commonly used extinguishers – Carbon Dioxide, Powder, Foam and Water. Today, we’re going to be talking about other types of extinguisher you may come across or need for a particular application.
Until the early 2000s, Halon 1212 (bromochlorodifluoromethane) was a very commonly used fire extinguishing agent. Each canister was likely to contain only a few kgs of gas which made the extinguisher very portable and light. Halon itself was very useful, being effective in electrical fires including delicate equipment and additionally, unlike carbon dioxide, it was also effective on Class A fires and those fires involving flammable liquids.
As Halon was a CFC, meaning that halons deplete the ozone layer, its manufacture was ceased in all countries who were involved in signing the Montreal Protocol, which was an international agreement to phase out use of ozone depleting substances. Halon can still be used in exceptional circumstances, such as on aircraft where there are no suitable alternatives. As it is no longer manufactured, this is achieved through recycling.
While research on suitable replacements continues and has already provided alternatives, the replacements are mainly used in fixed systems rather than portable extinguishers, where there is no significant demand.
Some extinguishing agents are designed for very specific types of fire. In the case of cooking oil fires – Class F, a fire blanket may be sufficient, but in some professional kitchens, the amount of cooking oil in the deep fat fryers might be too great for a fire blanket to be suitable for use. A Class F (saponification agent) extinguisher works by effectively converting the flammable oil into a ‘soap’, the discharge rate is slow to avoid splashing and displacement. The alternatives – a foam extinguisher for example, are not able to sufficiently cool the oil to avoid re-ignition. A foam extinguisher and CO2 can also both cause splashing upon application.
BS 7937 used to be the British Standard which gave performance requirements for such extinguishers, but this was replaced in 2004 by BS EN 3-7:2004+A1:2007.
Special extinguishing agents are also available for Class D fires which involve flammable metals and further information can be found in the British Standards.
In Part 8 of this series, we will lay out the relevant standards for fire extinguishers in Europe and take a look back at how it was in England and Wales prior to those changes. 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.