The LWF Blog

Fire Safety for Facilities Management Personnel – Gaseous System Agents – Part 249

April 22, 2024 11:19 am

Lawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 248, LWF began to discuss gaseous systems and the relevant applications. In part 249, we continue by talking about the specific agents used in gaseous fire suppression systems.

Up to the early 1990s, fixed firefighting systems would most likely contain one of the following gases; carbon dioxide, halon 1211 or halon 1301.

Halon 1301 was particularly popular for use in total flooding applications, such as for computer suites. The gas was extremely effective at suppressing fire and was also low-toxicity and therefore people in the area during or soon after the system was used would not be harmed by the gas.

CO₂ was also used, but in the concentrations necessary for fire suppression systems, would be lethal to persons or animals in the area. Stringent safeguards are required to avoid exposure to occupants. This obviously caused limitations in the use of CO₂ for total flooding applications and it is mainly used in areas such as transformer rooms that are only visited occasionally by trained persons. Despite the obvious issues with the use of CO₂ it remains one of the most frequently used agents for local application systems within a larger volume. As an example, a local application system may discharge onto one localised risk, e.g. a particular machine contained within a larger area.

Around the same time as CFC gases were found to contribute to the depletion of the ozone layer, halons were found to have the same effect. While this discovery benefitted our planet in that environmental controls were introduced, it was a significant issue for many applications in total flooding fire suppression.

European legislation required that all existing halon installations be decommissioned by 31 December 2003, other than in the case of certain critical uses, such as military and aerospace applications. The Channel Tunnel and associated installations and rolling stock are also deemed critical use for which the use of halon is permitted. A fire in the Channel Tunnel without low-toxicity halon gas suppression could result in a significant disaster, although reports from Eurostar and others in the intervening years indicate that some applications have been replaced by newly developed alternatives.

In part 250 of this series, LWF will continue talking about gaseous suppression and total flooding systems. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.

Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 35 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.

 

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.