The LWF Blog

Fire Engineering for Healthcare Premises – Fire Detection & Suppression – Part 50

August 31, 2021 11:14 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 49 of Fire Engineering for Healthcare Premises, LWF began to look at Smoke Detection. In part 50, we consider sprinklers and other common types of system that can be used to suppress fire.

Although many people think of sprinklers as a fairly recent innovation, they have actually been in use since the 1880s, along with relevant rules for their installation. Sprinkler systems are most commonly employed in commercial buildings, although there is increasing take-up in the residential market.

At its simplest, a sprinkler system is a network of pipes containing water with spray heads to distribute the water in a fire situation. An automatic sprinkler system contains temperature sensors within the spray heads. The sensors are often a simple glass bulb or fusible metal link which breaks when a certain pre-determined temperature is reached. The triggering allows the flow of water from the pipework and through the spray head.

The most common type of sprinkler system is described as ‘wet’. This means that the pipework contains water under pressure up to the sprinkler head at all times. Where extremes of temperature can be an issue, ‘dry’ sprinkler systems can be used. The pipework in dry systems does not contain water at all times because it could freeze, expand and damage the pipework.

A deluge sprinkler system does not have sensors in each spray head, but instead is activated by a detector system. The supply of water is then released to the heads which are already open. Pre-action sprinkler systems are those where the pipework is dry until a fire is detected by a detector system, but then the release of water is controlled by automatic heads. With a pre-action system, the initial signal allows the sprinkler system to work, but each head will only operate if the required temperature is reached in that area.

The activation of a sprinkler system in the early stages of a fire can cause issues with evacuation. The cooling of the hot smoke by a water spray can lead to a loss of smoke buoyancy and the smoky layer may mix with the clean layer below, causing poor visibility in escape routes. Sprinklers should be a part of an overall fire safety plan.

In Part 51 of LWF’s blog series, LWF will discuss Fire Service intervention. 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.

Share this post