Gas extinguishing fixed firefighting systems

A new tracked changes version of the European standard on gas extinguishing systems has just been published. This blog post looks at what’s covered and what’s changed since the last version of the standard in 2008.

What does BS EN 15004-1:2019 – TC Tracked Changes. Fixed firefighting systems. Gas extinguishing systems. Design, installation, and maintenance do? It mainly supplies requirements and recommendations for the design, installation, testing, maintenance and safety of gas extinguishing systems in buildings, plants or other structures.

Such systems are typically used in places where water, foam or powder extinguishers aren’t effective or where they might cause significant damage. This includes places like IT server and computer rooms, archives, art galleries, laboratories or operating theatres. The standard describes total flooding systems that utilize electrically non-conducting gaseous fire extinguishants that don’t leave a residue after discharge. It also covers the characteristics of various gaseous extinguishants and the types of fire for which they are suitable.

The standard limits itself to extinguishants for which there are sufficient current data from appropriate independent authorities to enable validation of performance and safety characteristics. It doesn’t intend to say that only the extinguishants in the standard are “approved”, as other extinguishants may be equally acceptable.

Also, CO2 is not included as it’s covered by other international standards, and the document doesn’t apply to explosion suppression. At the beginning of the standard, Table 1 lists the extinguishants covered. They are: FK-5-1-12, HCFC Blend A, HCFC-123, HCFC-22, HCFC-124, HFC 125, HFC227ea, HFC 23, IG-01, IG-100, IG-55 and IG-541.

The tracked changes version

What does “tracked changes version” mean? Just that the document comes in two halves. At the back end, you get the full, 2019 standard. At the front end, all the changes between this 2019 version and the 2008 version are highlighted: additions in green and deletions in red. The intention is that users can clearly see what has, and indeed what hasn’t changed.

In the case of BS EN 15004-1:2019- TC, the standard has undergone an extensive overhaul. Some changes are editorial tweaks and some are necessary updates to things like Normative References. However, the substantive changes of interest to users are technical, the most important of which are as follows.

First of all, the terms “lock-off device” and “regulated system” have been introduced, as has a note on environmental properties, so users are aware of the global warming and ozone depletion potential of various extinguishants.

In the Safety section, new content looks at the maximum inert gas agent concentration at the NOAEL and LOAEL limits. Also, the sections on Distribution and Maintenance have been revised.

The other changes impact the Annexes which take up more than half the standard. In Annex B the procedures for flammable liquids and gases have been replaced by procedures for inflammable liquids and gases, and the reporting of results has been revised.

Annex C on test procedures has been extensively revised, including new sections on reporting of test results and new content on extinguishing agent concentration, the cold discharge test, and agent concentration sensors.

Annex E “Door fan test for determining of minimum hold time”, has introduced values for Interface Thickness (It) and Interface Position (Ip) and the method of estimating F has been revised.

In Annex G on safe personnel exposure guidelines, the extinguishants HFC 236fa and CF31 have been deleted. In Annex H, “Flow calculation implementation method and flow calculation verification and testing for approvals” has been revised, including the addition of content on the modular validation process for calculation software method.

This tracked changes version brings the standard up to date and clearly shows what’s new. It will be extremely useful to anyone working with gas extinguishing systems.