The LWF Blog

Fire Safety for Facilities Management Personnel – Gaseous System Agents – Part 252

May 13, 2024 11:05 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 251, LWF discussed halocarbon and inert gases used in total flooding applications. In part 252, we will continue to discuss inert gases and halocarbons, as well as the relevant design codes.

When considering the safety of building occupants and the use of gaseous system agents used in total flooding applications, as stated earlier in this blog series, stringent safety measures must be in place for the use of CO2 as exposure can cause symptoms ranging from headache, confusion and dizziness through to death by suffocation.

Exposure to other fire extinguishing gases should also be avoided, although their low toxicity is such that they may be kept in automatic mode of operation while people are present in the protected room. There should be an audible warning of impending gas discharge, along with a time delay before the gas is released into the area to allow people to evacuate first. Controls may also be provided where considered appropriate, to allow occupants to manually delay the discharge.

The relevant design code for CO2 systems is BS 5306-4

A suite of design codes for halocarbons and inert gases is published as 15 parts of BS ISO 14520, beginning with BS ISO 14520-1 from which the other standards can be reached.

The components of a typical gaseous extinguishing system are as follows:

  • An agent storage facility
  • A means of automatic fire detection (and a means for initiating gas discharge)
  • Manual release controls
  • A network of pipes and discharge nozzles
  • A means for switching the installation from the auto/manual mode to manual only
  • A means for total isolation of the system

A gas storage facility commonly comprises a central bank of storage cylinders (usually sited outside the protected area, although in some circumstances, namely engineering, containers may be distributed throughout the protected area).  For very large CO2 installations, the gas may be stored at lower pressure in a refrigerated tank.

In part 253 of this series, LWF will discuss the remaining items on the list of components of a typical gaseous extinguishing system. 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.

Share this post