This is a economical and effective method of retaining fire doors, and is activated to release the fire door when it senses the fire alarm sounding. These are quick and easy to install, and being battery operated do not require any untidy or costly external wiring.
However, it must be noted that this does not replace a hydraulic door closer; and is subject to the alarm sounder functioning properly – if this does not happen the door will not close. One other drawback with this system is the fact that the batteries have to replaced on a regular basis, incurring further costs and hassle.
The standard Magnetic Door Retainer unit is the traditional approved method of holding open a fire door. The units are wired on a dedicated circuit interfaced electrically with the fire alarm, and release automatically if the power supply is removed (i.e. on activation of the Fire Alarm System). These units normally require a return wall for mounting although depending on the circumstances, a floor mounting version and chain mechanism are also available.
This is an advantageous option for a fully compliant system – particularly if the hydraulic door closer’s are already in place – which will release automatically in the event of a power failure, and in this sense is a step above acoustically actuated units. However, it only holds the door in a fully open position, and does not remove the action of a hydraulic door closer, which would have to be installed separately.
Electromagnetic door systems are the total solution to every problem in this area. A single unit, they look very like the standard hydraulic door closer, and combine the functions of a door closer and a door retainer into a single unit. This is obviously much more aesthetically appealing than having additional units on the door and return wall.
In the normal / standby mode, the hydraulic closer function is disabled. In the event of activation of the fire alarm system, the hydraulic closer function is enabled again, shutting the door and containing the fire.
The outstanding advantages are:
1. Two alternative set up modes available as standard;
FreeSwing mode- Removes the hydraulic door closer action so that in stand-by mode the door can be easily opened/closed and the angle of the door can be changed to any position.
2. Hold-Open Mode
Door is held open and only closes on activation of the Fire Alarm System. As the unit is fitted directly to the door, there is no requirement for a return wall.
3. Releases automatically in the event of failure of the mains supply.
4. Incorporates local release switch to enable mechanism to be tested/manually released.
5. Does not require the installation of a separate door closer as with other alternatives.
6. Available in wide range of metallic and RAL colour finishes.
HM Government (Fire Safety Risk Assessment Guide for Residential Care Premises – ISBN-13:978 1 85112 818 1).
Page 126 states as follows:
“In all cases the automatic device should release the fire-resisting door allowing it to close effectively within its frame when any of the following conditions occur:
– the detection of smoke by an automatic detector;- the actuation of the fire detection and alarm system by manual means e.g. operation of break glass call point;- any failure of the fire detection and alarm system;or- any electrical power failure.
Office of the Deputy Prime Minister – The Building Regulations 2000 – Approved Document M
Page 34 states as follows:
Internal doors will satisfy Requirement M1 or M2 if:
– Fire doors, particularly those in corridors, are held open with an electro-magnetic device, but self-close when activated by smoke detectors linked to the door individually, or to a main fire/smoke alarm system;- The power supply fails;- Activated by a hand-operated switch;- Fire doors, particularly to individual rooms, are fitted with swing-free devices that close when activated by smoke detectors or the building’s fire alarm system, or when the power supply fails.
