The LWF Blog

Fire Safety for Facilities Management Personnel – Fire Detection & Fire Alarms – Part 186

January 30, 2023 12:32 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 185, LWF looked at the elements of a fire alarm system. In part 186, we discuss the types of detector and what circumstances they are best suited for use in.

Heat detectors have a typically slow response time when compared to smoke detectors. The response time of a heat detector means that it would not be appropriate for use in an escape route or electronic equipment rooms, where a small fire could result in significant losses.

However, heat detectors are necessary for use in areas where dust, fumes etc. may mean that smoke detectors are not a viable option. In a kitchen, for example, the particulate matter and steam emitted by the cooking processes would result in smoke detectors being triggered unnecessarily and so heat detectors are the preferred option. Heat detectors may also be the preferred option in areas where a fire is likely to cause a high heat output rather than significant smoke, such as can be the case with some flammable liquid fire risks.

Heat detectors may be used in rooms or enclosures formed of fire-resisting construction, where the objective is simply to provide a warning before the integrity of the construction is threatened, however, where smoke detectors would provide more warning, it would seem sensible to use them.

An example of how heat detectors can be used is in rooms which adjoin the escape route. Traditionally a hotel for example, may have placed heat detectors in its rooms rather than smoke detectors to ensure a warning is given before common escape routes are threatened, rather than to provide an early warning to the occupants in the room of fire origin. The reason this decision might be made is that smoke detectors are much more likely to present false alarms and in a large commercial building like a hotel, constant false alarms can be very disruptive to the occupancy. More recently, smoke detection has been used in hotels, positioned better and less prone to false activations has reduced unwanted fire signals. Investigation periods can also be introduced to reduce the likelihood of an evacuation signal.

The standard heat detectors used in most situations are the fixed temperatures/rate of rise point type. However, near ovens or in laundry rooms, for example, fixed temperature detectors should be used to monitor any sudden rise in ambient temperature.

Line heat detectors are used for special applications where the geometry of the space to be protected allies particularly to their design, possible applications include cable tunnels and under escalators.

In part 187 of this series, LWF will begin to look at smoke detectors. 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.