The LWF Blog

Fire Safety for Healthcare Premises – Types of Fire Alarm System – Part 118

March 9, 2020 3:03 pm

In LWF’s blog series for healthcare professionals, our aim is to give information on best practice of fire safety in hospitals and other healthcare premises. In part 117, LWF considered the definition of system type given in HTM 05-03. In part 118, we continue by looking at Category L4 and Category L5 Automatic Detection Systems.

A Category L4 system is one which is installed in the parts of escape routes which comprise circulation areas and spaces, such as corridors and stairways. The purpose and importance of a Category L4 detection system is to warn of smoke in escape routes and in doing so, protect the safety of building occupants.

The use of a Category L4 system does not mean that detectors cannot be installed in other areas of the building in addition to circulation spaces and areas.

A Category L5 system is one which is designed to fulfil a specific fire safety objective (other than those satisfied by an L1, L2, L3 or L4 system).

The design of an L5 system is often based on a completed fire risk assessment or is to satisfy the requirements of a fire engineered safety solution created for the premises. It is possible that the fire engineered solution requires a departure from standard guidance and the system is a supplementary installation to ensure fire safety, or it is a part of the operating system for a fire protection system.

A Category L5 system may even be as simple as one automatic fire detector in one room, if the circumstances indicate that if a fire were to start in that area, it could cause significant risk to occupants in the room or elsewhere in the building.

Equally, a Category L5 system could be a comprehensive detection system operating throughout large areas of the building, if the building has a lower standard of fire resistance than is normally provided in buildings of that type.

It is also true that a Category L5 system may incorporate the protection provided by an L2, L3 or L4 system too.

Whichever category a fire detection system falls into, it should be designed for the building, risk assessment and fire safety plan in place for that environment. It is never appropriate to employ a ‘one size fits all’ approach in fire safety, as even slight differences in procedure, staffing or practices can impact on the overall provision.

In Part 119, LWF will begin to discuss System Technology. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.

Lawrence Webster Forrest has been working with their clients for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact LWF on freephone 0800 410 1130.

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.

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