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Fire Safety for Healthcare Premises – System Technology for fire alarms – Part 145

September 14, 2020 1:46 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 144, LWF looked at two of the types of addressable fire alarm system available – two state and analogue. In part 145, we finish considering analogue, before discussing the last type of addressable system available, multi-sensor.

Most analogue systems have the facilities to read off the current analogue values of all detectors on the system. This ability assists with enabling identification of any detectors needing to be cleaned or which might be more prone to unwanted fire signals (UwFS) due to high levels of pollutants in that area.

A multi-sensor addressable fire alarm system differs from two-state or analogue in a significant manner. In the past, fire alarm systems had detector heads which were able to sense one of the signs of fire – heat, smoke or flame. This was achieved using a singular methodology such as optical scattering or the use of an ionisation chamber.

A multi-sensor detector fire alarm system has detector heads which incorporate more than one sensor type and can therefore detect more than one of the indicators of a fire. In some systems, by comparing the signals from different sensors it is possible to avoid UwFS. For example, a detector close to a source of steam using an optical device may give an UwFS, but a multi-sensor detector incorporating a heat or ionisation chamber sensor in addition, may be able to avoid a false alarm because both signals were not positive.

The use of multi-sensor fire detectors is still relatively uncommon, but with mounting evidence to show the reduction in UwFS in environments which are prone to them, it is likely their use will continue to increase.

BS EN 54-29:2015 – Fire detection and fire alarm systems. Multi-sensor fire detectors. Point detectors using a combination of smoke and heat sensors is the UK/European standard for multi-sensor systems, released in 2015.

In LWF’s next blog, we will begin to look at HTM 05-03 Part J which is concerned with the application of fire engineering principles in healthcare premises, it will be titled ‘Fire Engineering for Healthcare Premises – Overview – Part 1’. 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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