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BS 7273-4: Actuation of Release Mechanisms for Fire Doors 2007 Tom Welland, Fire Services Manager, Fireco Ltd
BS 7273-4: 2007 concerns the actuation of release mechanisms for fire doors. It was published by BSI and came into effect on the 30 April 2007. The standard makes recommendations for the design of the interface between a fire alarm system and devices that open, unlock or release doors in the event of a fire. It applies to all aspects of the interface between these mechanisms and a fire detection and fire alarm system, including those that utilise acoustic coupling and radio transmission. It does not recommend whether these mechanisms should, or should not, be used in any given premises or in any particular circumstances. The Regulatory Reform (Fire Safety) Order 2005 (RRFSO) requires decisions about most fire precautions to be based on a fire risk assessment, and BS 7273-4 is no different.
The standard is divided into 3 different categories, so, using the findings from an suitable and sufficient Fire Risk Assessment and with reference to BS 5839-1, it should be possible to determine which category of device will suit any specific situation.
BS 7273-4 defines three different categories of actuation, each with a set of criteria for failsafe operation under defined conditions. Category A requires failsafe operation even when there is loss of both the mains and standby power supplies to the fire detection and fire alarm system, as well as various fault conditions on the wiring. Category B is less onerous in that not all of the fault conditions specified for Category A actuation would close held open doors. Category C actuation addresses situations where there is no direct communications path between the fire alarm control & indicating equipment and the release mechanism.
Critical path to application The critical signal path distinguishes the category of installation. It is a means of communication between the CIE and the associated fire door retainers. If the transfer of information between the CIE and the hardware is compromised, the fire door retainer must fail-to-safe. It is important to note that the fire alarm sounder circuits are not deemed to be part of the critical path for acoustically triggered fire door retainers. Fire doors are vital in the protection of means of escape, therefore if a fire door retainer such as a Dorgard is being used it is essential that the actuation of the fire door release is reliable. A fire door retainer failing to release could seriously hinder any evacuation and potentially increase the chance of fatalities.
The 'Kick the Wedge' fire safety survey, commissioned earlier this year by Fireco, revealed that almost 70 percent of premises audited for fire risk by accredited UK fire risk auditors and fire safety officers were found to be wedging open fire doors illegally. This research highlights how it is important that, if specifying a fire door retainer, reference is made not only to BS 7273 as an informative guide, but that a site specific Fire Risk Assessment is carried out. If, after identifying that a fire door that needs to be retained, the decision is made to specify a fire door release mechanism compliant to one category, it is not safe to presume that this category of actuation will be suitable for every location. 'Appropriate' solutions. In addition to BS 7273-4 two recent pieces of fire prevention regulation, relating to non-domestic premises, point to the principle of 'horses for courses' when considering the balance between over or under specification of fire safety equipment.
The RRFSO stresses that in making fire safety arrangements the 'responsible person must make and give effect to such arrangements as are appropriate, having regard to the size of undertaking and the nature of its activities, for the effective planning, organisation, control, monitoring and review of the preventive and protective measures.' Similarly, Approved Document B - Volume 2: Buildings Other than Dwelling houses, which came into force in April 2007, makes the point that 'there may well be alternative ways of achieving compliance' using the approved document, and 'there is no obligation to adopt any particular solution contained in an Approved Document if you prefer to meet the relevant requirement in some other way.' Fire safety regulators are increasingly taking a realistic approach to the economic impact of tighter regulation, considering issues like affordability, non-disruptive installation, and business continuity - all critical factors when determining the technology best suited to bringing about a particular fire safety solution.
An example of BS 7273-compliance In addressing issues of greater flexibility in response to compliance, new cost-efficient technologies are evolving that can be rapidly installed and meet all commissioning criteria, yet still keep costs to a minimum. For example, Fireco's latest generation of stand-alone products based on the Dorgard principle of 'listening technology'. System X uses the same acoustic listening technology in the transmitter unit (TX) as the acoustic Dorgard. Upon verification of a fire condition the TX will transmit a radio signal to the Dorgard X fire door unit to release the fire doors, preventing the spread of fire and smoke. The advantage of System X over the acoustic Dorgard is that Dorgard X units are remotely triggered by the TX unit using radio technology and not locally triggered by sound. System X uses a trigger that cannot be obscured by the ambient background noise.
System X also has the capacity to operate other fire safety equipment such as wireless fire alarms that use vibration technology to alert deaf or hard of hearing sleepers who may be in danger of not hearing a fire alarm. System X exceeds the requirements of BS 7273 Category B and Category C though it should be remembered that automatic Fire Detection is always required where a fire door retainer is installed. Whether Dorgards are self-installed or fitted by a competent engineer, the installation must always be signed off using a commissioning certificate with a maintenance schedule put in place.
Both certificate and maintenance schedule should be included in product/system manuals. Following commissioning, it must be confirmed that the user fully understands the operation of the equipment installed. There also needs to be adequate co-operation and co-ordination between the installer, manufacturer and user with their responsibilities defined prior to installation. With the release mechanism installed and a commissioning certificate completed it is vital that a maintenance and inspection schedule is in place so that preventative measures can be taken to ensure continued reliability. Cost-saving installation System X offers specifiers and installers greater flexibility when managing a building's fire safety. One of its major benefits is that by using wireless technology System X delivers significant savings in time and cost of installation, when compared with hard-wired systems. Disruption to occupants is minimised because System X requires no on-site alterations to the building's fabric. In fact, the cost of a comparable hard-wired solution could be between 150 – 400 percent higher than the installation of a Dorgard X unit. Installers will also understand the advantages of an easy-to-install, standards-compliant system that can be rapidly commissioned, with significant profit margins on every unit installed.
With more than 250,000 units sold in the UK alone, Dorgard offers the simplest, most cost-effective way of legally holding open fire doors safely in any position, automatically releasing them should the fire alarm sound.
For more information contact Fireco on 0845 241 7474, e-mail sales@firecoltd.com or visit www.firecoltd.com.