The LWF Blog

Fire Safety for Facilities Management Personnel – Fire extinguishing appliances – Part 222

October 9, 2023 10:47 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 221, LWF discussed carbon dioxide fire extinguishers. In part 222, we consider some of the other agents used in fire extinguishers, some in current use and some in past years.

Until the mid-1990s, halon 1211 (bromochlorordifluoromethane) was produced widely and commonly used in fire extinguishers. The extinguishers only contained a few kg of the gas and were therefore very portable and light. Halon could be used on live electrical equipment and was also very effective on Class A fires and fires involving flammable liquids.

The manufacture of halons was banned by the EU in 2000 and was implemented in the UK in 2003 because halons deplete the ozone layer. All halon extinguishers should now have been replaced in most premises, but they are permitted for some critical uses, such as on board aircraft and in the channel tunnel, where the extinguisher is essential to protect life and there are no viable alternatives. Halon is reclaimed for the purpose and its use is not illegal.

The search for a halon replacement has been extensive and various fixed systems now operate using the resulting developed gases. They have not, however, found their way into portable fire extinguisher use, as there is no significant demand.

There are various agents used in fire extinguishers for specific applications. For example, fire extinguishers produced specifically for use with Class F fires (those involving cooking oils and fats). While there are other fire-fighting tools commonly used in a kitchen, a fire blanket would not be suitable for the depth of cooking oil in a deep fat fryer. Foam can create a barrier over burning oil to block the fire’s access to oxygen, but the high auto-ignition temperature of the oil is such that the high temperature persists for an extended period and can result in the destruction of the foam layer and re-ignite.

In the case of vegetable oil, once it has ignited for the first time, subsequent re-ignitions are more likely as the auto-ignition temperature is reduced.

The fast and somewhat forceful discharge from CO² extinguishers and foam extinguishers can cause splashing of the burning liquid, which is not safe.

In part 223 of this series, LWF will talk about the agents used in Class F extinguishers before discussing the relevant standards. 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.