The LWF Blog

Fire Engineering for Healthcare Premises – Fire Detection & Suppression – Part 46

August 2, 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 45 of Fire Engineering for Healthcare Premises, LWF looked at what is meant by the term ‘fire severity’ before beginning to discuss fire detection and suppression. In part 46, we will continue to talk about fire detection and suppression.

When a fire detection system is able to provide the location of a fire, that information can be passed to staff in the building and/or building occupants depending upon how useful the information could be.

The provision of such information allows people to take appropriate action and to pick an exit most appropriate for leaving the building to a place of safety. Research has shown too that informative fire warnings are taken more seriously by building occupants and their reaction times are correspondingly faster.

Progressive horizontal evacuation also relies on a fire detection and reporting system detailing the location of the fire.

When a fire detection system is designed, the type and location of the detectors is based on various factors, including the anticipated fire type, building usage and the building’s characteristics affecting the movement of smoke. The sensitivity of the detectors will be set in order to achieve the ideal balance between a rapid fire detection time and avoiding unnecessary, disruptive and potentially dangerous false alarms.

There are many different types of detectors available for use as part of a fire detection system and most are suitable only for certain circumstances.

• Ultraviolet Light (UV) between 170 and 290 nm approx.
• Infrared Light (IR) between 650 and 850 nm approx., thermal radiation
• Flame flicker which monitors optical light intensity variations
• Ionisation which detects the number of particles in smoke, most smaller than 0.1 μm
• Optical detectors which detect visible smoke particles, larger than Ionisation detector levels. Single point detectors which detect the light back-scattered from the smoke; beam detectors measure light attenuation.
• Heat detectors which detect high temperatures, approximately between 70 and 100 Celsius.
• Rate of heat rise detectors which detect rapid heat increases
• Line or aspirated detectors which detect smoke particles or specific gases. They draw in samples of smoke which are analysed in a common analyser.

 

In Part 47 of LWF’s blog series, LWF will continue to discuss fire detection and suppression systems and how they work. 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.