The choice of audible and visual alarms for use with fire detection systems has grown enormously in recent years. Rowland Davies explains the key drivers for this not-so-silent revolution.
Audible and visual alarm products have not, until recently, been a main focus for development in the fire detection industry. While fire detection technology was evolving to give the industry a choice of conventional or intelligent systems and devices specific to smoke, heat, fire, carbon monoxide or combinations of these key indicators, audible and visual warning devices did not keep pace.
Bells traditionally provided the main means of alerting occupants to a fire incident and it is only gradually that these are being superseded by sounders using an electronically generated tone. Visual warnings were simply not a mainstream requirement.
Within the last three years or so, however, the situation has changed radically. A raft of new legislation and a shift in industry perspective regarding roles and responsibilities have placed more emphasis on fire prevention than ever before. These new regulations include:
– the UK’s Disability Discrimination Act (DDA), which was introduced in October 2004 and requires consideration of the inclusion of visual alarms, as well as audible alarms to take into account those who may have impaired hearing
– the revised Approved Document M of the Building Regulations for England and Wales which stipulates that, in addition to smoke detection, visual and audible devices should be installed in every bedroom and every bathroom in buildings such as hotels and accommodation blocks
– tighter regulation now governing fire protection in houses in multiple occupation (HMOs)
– the Regulatory Reform (Fire Safety) Order, which came into force on October 1st 2006 and applies to virtually all commercial premises in England and Wales. The Fire Safety Order requires the named Responsible Person for the fire detection system in a building to consider everyone who might be on the premises, and asks that particular attention be paid to people who may have a disability or anyone who may need special help. In short, the Fire Safety Order is intended to reduce confusion regarding responsibilities of businesses and individuals under fire safety law.
Taken in combination, these new rules could mean doubling the number of alarm devices in a fire detection system. As well as the obvious rise in cost, the knock-on implications include additional wiring and therefore longer installation time – to say nothing of the increased difficulty in appropriately siting all the necessary devices.
Simplification is key
Increased complexity is not desirable in a life-critical system. Clear and unequivocal warnings must be the overriding aim – particularly in premises that are unfamiliar to occupants, such as a holiday resort, hospital or student accommodation.
To address this issue, some manufacturers have added new warning devices to pre-existing ranges that combine several functions in a single unit. For example, Apollo expanded its AlarmSense range for houses of multiple occupation (HMOs) by adding a sounder base capable of raising a local alarm so that an incident in one dwelling, such as burning toast, can be dealt with by the occupant without raising a general evacuation. The sounder initially gives a local alert for two minutes, during which time it may be cleared by the occupant if it is recognised as a false alarm. If the local alert is not cleared within this time, a general alarm is sounded throughout the building. There are also devices that not only combine the base and sounder functions, but also provide high intensity red LEDs that flash in the event of an alarm, aiding compliance with the Disability Discrimination Act.
Manufacturers are also alive to the possibility that application-specific ranges may need to be linked to other life critical equipment. This has led to the availability of devices like relay modules that enable products such as standard conventional sounders and beacons to be connected to an HMO-specific system. This could be used, for example, to indicate the occurrence of a local alarm to a warden, or to trigger a staff alarm. It could also be used to switch on an external beacon at the premises, to assist fire fighters attending an alarm.
Combining forces
In addition to modifying or expanding existing application-specific product ranges, fire detector manufacturers have also responded by looking at ways in which generic ancillary products can be combined into a single unit without compromising performance. The results include more versatile versions of existing audible and visual alarm devices, as well as hybrid products, like bases with integral sounders, and combined sounder beacons. In Iceland, for example, the Grand Hotel in Rejkjavik was recently equipped with a new intelligent fire detection system that features ancillary base sounders in every guest room. These loop-powered devices are designed to respond to signals from the associated detector to raise the alarm.
Loop-powered beacons are also available. Because it is loop-powered the beacon does not require a separate circuit, which means savings on wiring, interface equipment and installation time. This type of device is ideal for use as a visual warning for the hard of hearing; in areas with high background noise such as machine rooms and engine test bays; or in situations where an audible alarm is undesirable or unnecessary. Examples include hospital operating theatres and intensive care wards, television and radio studios, cinemas and theatres.
The fire detection system at the Mater Dei Hospital in Malta takes full advantage of new sounder and beacon technology. The new
800-bed hospital consists of two main and five satellite buildings, all of which interconnect at ground level. Ranging between five and seven storeys in height, the accommodation includes subterranean accommodation levels and four storeys of underground car parking.
The fire detection system consists of 15 addressable fire control panels networked together. These panels control over 9,000 Apollo Discovery intelligent fire detectors, 2,300 sounders and 1,200 manual call points. All areas are equipped with audible alarms, with the exception of residential wards for the bed-ridden, where the alarm will show only at the nurses’ station to avoid distressing the patients. Plant and service areas, where high noise levels may be an issue, have both audible and visual alarms. Wherever an alert is raised, the information is fed back to the security guard rooms and the nurses’ stations nearest the incident.
An interface between the fire alarm network and the BMS enables complex cause and effect sequences that ensure the evacuation plans for the building are activated correctly. These requirements vary depending on the occupants and use of each area.
As fire and safety regulations become more and more stringent, fire detector manufacturers are really striving to combine the maximum number of functions in a single device, in order to keep costs down and installation simple. A sounder beacon base, for example, combines a loop-powered sounder and beacon with an integral base, so a detector can be fitted to it. The device may also feature an inbuilt isolator, so even a basic model can provide four functions at a single point – audible alarm, visual alarm, detection and short circuit isolation.
Manufacturers are also continuing to refine the features available in the new generation of audible and visual alarm devices. The most recent sounder/beacon bases are capable of being assigned to more than one group of products at a time if required. A single command can now be used to synchronise the sound and light pulses, avoiding confusion. Some sounder beacon bases have the facility to set the volume of each device individually and control the sound and flash independently. In addition to warning of fire, tones can also be used for other purposes, which is ideal for schools – so the old bells we discussed at the beginning of this article are being consigned to history!
Conclusion
Increasing legislative demands regarding warning procedures in life critical situations could potentially have made fire detection systems more costly and complicated. The reassessment and redesign of audible and visual alarm equipment that happened as a result, has lead to the development of more reliable and more sophisticated products. This new hybrid race of sounder/beacons has once again simplified compliance for the designer and installer.
As yet, the influence on the fire protection industry can only be guessed at, but the same qualities that have enabled the industry to adapt to previous change will no doubt ensure that we continue to achieve our ultimate goal – the saving of lives.
Rowland Davies is marketing services manager at Apollo Fire Detectors.
