The LWF Blog

Facilities Management & Fire Safety – Fixed Fire-Fighting Systems – Part 1

March 30, 2017 2:15 pm

In this Fire Safety blog series for those who work in Facilities Management, we will start to look at Fixed Fire Fighting Systems in this blog.  A fixed fire-fighting system is a system which is permanently installed in a building and is designed to extinguish or suppress fires. It can work either by automatic or manual control.


While there are systems referred to as fixed fire extinguishing systems, it is not necessarily an accurate moniker as the majority of such systems are designed to control or suppress smoke and fire. While a definition of fire extinguishing would be fairly self-explanatory, fire suppression and fire control have different uses and applications of which you might not be aware.


Fire Suppression could be described as the reduction of the heat-release rate of a fire, which results in a lower level of burning.


Fire Control differs in the way that it limits fire growth and protects the structure of the building by the cooling of flammable objects, fire gases and potentially by pre-wetting any combustibles in the area, making them harder to burn.


Fixed fire-fighting systems are usually classified into the appropriate extinguishing agent, e.g. water or aqueous systems/non-aqueous systems, however, this is a broad-brush approach and in order to pinpoint the correct system for any given circumstance, the actual nature of the agent used, or its physical nature and method of application must be considered.


Firstly, using the broad category of Aqueous/Water based systems, there are the following types of fixed fire-fighting system:


Sprinkler – Mainly suitable for Class A fires in buildings


Drencher – Prevents the spread of fire between buildings


Water Spray – Works to extinguish Class B fires which involve liquids with high flashpoints, above 66 degrees celcius. This can also be sub-categorised as ‘High Velocity’. When the water spray is used and sub-categorised as ‘Medium Velocity’ it is suitable to control or extinguish Class B fires on liquids with low flashpoints, below 66 degrees celcius. It is also used to protect plant items from radiation from an adjacent fire.


Fine Water Spray – For the control and extinguishing of Class A and B fires.

Foam – coming in three types – low, medium and high expansion, the first two types of expansion are suitable for Class B fires and high expansion is suitable for Class A fires.


In the next part of this series, we will look at the types of non-aqueous fire-fighting systems. 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.


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