The LWF Blog
Facilities Management & Fire Safety – Locating Sprinkler Heads – Part 13June 22, 2017 12:06 pm
In this blog series for those who work in Facilities Management and who have an interest in or responsibility for fire safety, we have been looking at fixed fire-fighting systems. A sprinkler system design is usually as individual as the building which contains it. In part 13, we will look at how sprinkler heads should be located.
In the vast majority of cases, if a sprinkler system is present in a building it should be throughout. Partial coverage in any premises is unusual and should be avoided. If you consider a fire that starts in another part of the building not covered by sprinkler protection, spreading to the area which contains sprinklers, the size and intensity of the fire would already be much greater than a fire which starts in a sprinklered area. The system would therefore not be effective against such a fire.
There are certain areas of a building, however, which would have to be left without sprinkler protection for safety reasons. Examples might be rooms which contain electrical switchgear, transformers, molten metal, oil and flammable liquids. In these cases, the unprotected area must be individually compartmented and comprised of materials of adequate fire resistance, usually 120 minutes duration. This would ensure the fire could not spread beyond that area within the 2 hours and give sufficient time for safe evacuation of the premises and for the Fire Service to attend.
In cases where buildings are linked and only one has sprinkler protection, it is essential that the construction is separated with fire resistant materials which have a duration of 120-240 minutes, according to BS EN 12845. This may vary depending upon circumstances and so an individual fire engineering evaluation should take place to ascertain the necessary safety requirements.
The performance of sprinkler systems has been monitored closely over the years and the safety benefits are proven. Studies show that between 95-98% of all fires which are large enough to trigger the sprinkler system will be extinguished or controlled by that system. Of the 3-5% which are not successful, many are due to human error in regards to sprinkler system maintenance and operation.
The likelihood of sprinkler discharge when there is no fire is also very low. Leakage tends to be the result of accidental damage to the system, pipework freezing in extremely cold weather or at the other extreme, high temperatures. Corrosion may also occur in some environments and a system where damage, extremes of temperature and potentially damaging atmosphere occurs should be subject to a more intensive and regular maintenance schedule to overcome the potential for damage.
In the vast majority of environments where sprinkler systems are found, such as office buildings, the systems are extremely reliable and leakage is a very rare occurrence. While a traditional wet sprinkler system can even be seen in use in computer suites, it is often the case that pre-action systems are in use to avoid unnecessary water damage in case of fire.
In Part 14 of this series, we will look at the checks that should be undertaken on a regular basis to ensure the sprinkler system can operate optimally. 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.