The LWF Blog

Fire Safety Engineering for Design – Fire Detection & Alarm Systems – Part 156

October 30, 2023 12:15 pm

LWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 155, LWF discussed aspirating systems and what environments they may be suitable for. In part 156, we will look at flame detectors and gas combustion detectors.

Flame Detection

Flame detectors might use optical or infrared technology to detect the presence of a flame. Flame detection is most commonly used for specialist applications, where immediate detection of flames is required – usually, where high-value assets are to be protected – in an aircraft hangar for instance.

They can be used effectively in an area containing materials most likely to produce fast-spreading flaming fires, such as flammable liquids.

The detector has two main types – ultraviolet flame detectors and infrared detectors. The UV flame detector detects the level of ultraviolet radiation within a flame, while the infrared is sensitive to the flickering component of the infrared radiation from a fire.

It should be noted that flame detectors do not detect smoke and would not be able to detect smouldering fires. They are best used either for specialist requirements or to supplement heat or smoke detectors in appropriate areas. They are not suitable for use as general purpose detectors and for most scenarios, have been superseded by video detection.

Gas Combustion Detection

A Gas Combustion Detector uses catalytic bead or infrared sensor technology to measure the amount of combustible gas present in air. Typical combustible gases include hydrogen, methane or natural gas, propane, ethylene and other hydrocarbons.

The most commonly-seen type of gas combustion detector, however, is a carbon-monoxide detector. These are particularly good at detecting a fire where the oxygen supply to the fire is restricted. They are very effective at detecting smouldering fires where the lack of heat or oxygen can mean fire development is fairly slow.

They may be used in residential properties where they act as monitoring devices to gas-fired central heating and there is a risk of air supply to the equipment being restricted or the flue being blocked.

A gas combustion detector is less affected than other types of detector by dust or steam induced false alarms.

In part 157 of LWF’s series on fire engineering, we will explore the disadvantages of gas combustion detectors before exploring video smoke detection. 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 since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 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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