The LWF Blog

Fire Engineering for Healthcare Premises – Fire Severity – Part 45

July 26, 2021 11:29 am

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 44 of Fire Engineering for Healthcare Premises, LWF looked at fire resistance in terms of stability, integrity and insulation. In part 45, we will look at what is meant by the term ‘fire severity’ before beginning to discuss fire detection and suppression.

Fire severity can be described as the quantitative measure of the effects of fire on the surrounding environment; a measure of the impact of fire destruction, the forces and temperature which could cause collapse of a building or part, or cause any other failure.

The severity of a fire can depend on the total amount of heat transferred to the structure in question, or the highest temperature achieved. The expression of fire severity may be in different terms:

Time – the equivalent exposure to a standard fire curve in a furnace

Temperature – the maximum temperature reached by a key part of the structure

Load-bearing capacity – the minimum load-bearing capacity

While such calculations and expressions of fire severity can be useful, a real fire situation will present very different time-temperature curves to the standard curve in a furnace. Most methods do not account well for structural system response to fire exposure. For this reason, expressing severity in terms of equivalent exposure may be difficult. It is preferable to perform calculations from first principles and may be necessary to do so.

Fire Detection & Suppression

A healthcare building’s fire protection strategy will centre on the fire detection and fire alarm systems in use. For life safety purposes, the fire detection and warning must be efficient in order to give sufficient time to enable complete evacuation of the hazardous area (including horizontal evacuation where such methods are in use) before conditions become untenable through breathability or visibility or both.

When a fire is detected by a fire alarm system, this may trigger other fire protection measures such as smoke curtains, smoke control systems or fire suppression systems.

In terms of property protection, rapid fire detection and alert allows prompt attendance by the Fire Service so firefighting can commence at the earliest opportunity and the fire can be extinguished before it grows and spreads.

In Part 46 of LWF’s blog series, LWF will continue to discuss fire detection and suppression. 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.