The LWF Blog
Fire Safety for Facilities Management Personnel – Structural Fire Protection – Part 157July 4, 2022 11:17 am
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 156, LWF discussed fire and smoke resistant doors. In part 156, we will continue to look at fire doors. In part 157, we continue to talk about fire resisting doors.
The most commonly-seen method of holding open a self-closing fire door is an energised electromagnet which holds the door open through the use of a metal pad on the door. If a fire occurs, the automatic fire detection system sends a signal which de-energises the electromagnet, allowing the door to swing closed.
Maintenance checks should regularly ascertain that the electromagnet and self-closing device are aligned horizontally, as a failure in this regard could mean the door is subject to twisting forces which could warp it and result in a door which does not fit the frame in which it sits.
Where the door is critical for the protection of means of escape, it should be fitted with a failsafe to ensure it closes in the event of power failure.
There are other types of door-release mechanism which enable doors to be held open on a normal basis and closed if a fire is detected. One such mechanism uses a plunger which holds the door through friction with the floor. The plunger is triggered and lifted by the sound pressure level of the fire alarm system. It is known as an acoustic fire door retainer.
BS 7273-4 suggests that acoustic fire door retainers may not be suitable for use in some situations, where fire doors are classed as critical use. For instance, if the door is to protect a single stairway that forms a part of means of escape from a building or part thereof. In addition, it suggests an alternative may be appropriate in buildings containing sleeping accommodation, e.g. hotels, hostels, care homes etc. This is due to the fact that, should the fire alarm system fail, the doors would not automatically release in a fire situation.
The Regulatory Reform (Fire Safety) Order 2005 also states that self-contained devices which are not directly connected to the fire alarm system, as in the case of acoustic fire door retainers, are unsuitable for use in doors which are designed to protect critical means of escape.
In part 158 of this series, LWF will continue to discuss the self-closing mechanisms of fire doors. 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 25 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.