The LWF Blog
Facilities Management & Fire Safety – Gaseous Systems – Part 22August 24, 2017 10:21 am
In this blog series for those people who work in Facilities Management and who have a responsibility for or interest in fire safety, we have been discussing recently the use of gaseous systems as part of a building’s fire protection plan.
In part 21, we established that although there are no circumstances in the UK where gaseous systems are a requirement through legislation, if the use of such a system in particular circumstances is proven to offer better protection than sprinklers, the building’s insurers may be able to offer an equivalent premium discount.
In Part 22, we will look at the agents used in gaseous systems currently and give a quick overview of halon, which is a discontinued substance. Up to the early 1990s, the gases which were used most commonly in gaseous systems were carbon dioxide, halon 1211 and halon 1301. Halons had certain advantages over carbon dioxide based systems, as exposure to carbon dioxide in high concentration is lethal to humans and all other animals.
Halons were found to be potentially damaging to the ozone layer in a similar way to CFC gases and European legislation required that all halon-using systems were to be replaced by 2003, with very few exceptions. The exceptions were classed as ‘critical uses’ and one of the few places that a halon system can still be found in use is in the Channel Tunnel, to fulfil the necessity of an effective flooding gas which will not harm any living being who comes into contact with it.
When halon was first phased out, carbon dioxide systems were the only gaseous system alternative, although many were disinclined to use it given the obvious risks.
While carbon dioxide systems are still commonly found, their use in total flooding systems tends to be limited to areas which are rarely visited by personnel, such as transformer rooms. In the main, it is used for local application only, such as directly onto a machine in an otherwise large and oxygen-filled space.
The use of a carbon dioxide system is subject to safety considerations laid out by the Health and Safety Executive and great care must be taken to ensure the circumstances warrant the use of the system and that after use, the building is cleared of CO2 prior to reoccupation.
Effective alternatives to halon are now available and these can be split into two categories – halocarbons and inert gases.
These are clean, gaseous agents which do not have a seriously adverse effect either on living beings or the ozone layer.
In Part 23 of this series, we will talk more about halocarbons and inert gases and how they work. 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.