The LWF Blog

Fire Safety for Facilities Management Personnel – Fire Detection & Fire Alarms – Part 188

February 13, 2023 12:19 pm

Lawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 187, LWF began to look at the types of smoke detectors and their uses. In part 188, we continue to discuss smoke detectors.

Smoke detectors are the most generally used type of detectors, being the mainstay for both property and life protection systems. However, they should not be used in areas where processes or environmental influences may cause false alarms. False alarms are not just a nuisance but can lead to dangerous complacency in building occupants when they hear an alarm and assume it is just another false alarm when, in fact, it is a real fire situation.

In escape routes, optical detectors only should be placed and in areas where the earliest possible warning of fire is required, such as server rooms or other sensitive electronic equipment, an equal usage of optical and ionization chamber detectors is often the chosen solution. It is also increasingly common for areas where early warning is required to be fitted with very high sensitivity smoke detection systems, often the aspirating type.

Beam detectors are often the best choice fiscally for large open areas such as warehouses. The efficacy of these systems is based on the transmitter and receiver being appropriately placed and attached to solid construction and ensuring that the beam ‘view’ will not be obstructed, e.g. by forklifts. Beam detectors are also seen in historic and listed buildings where a ceiling mounted detector may not be suitable for installation.

Aspirating smoke detection systems are those where a pump or fan draws in air samples through holes in small bore tubing or pipework within the protected space. The sample is processed by a central smoke detector. The detector itself may be ionization chamber or optical (typically optical) and is very sensitive to even the smallest presence of smoke in the air. It is possible to achieve sensitivity of several hundred times that of a ‘normal’ smoke detector. This level of sensitivity would not be appropriate in all environments, of course, as it may lead to false alarms.

In part 189 of this series, LWF will continue to discuss aspirating smoke detection systems and look at their appropriate usage. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.


Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 35 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.


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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