Fire alarm systems become wireless 3

Today wireless transmission is not only used in intruder alarm systems and in personal protection. Fire detectors are now also available in wireless versions. Furthermore, there is no doubt as to the performance of these battery operated detectors with built in radio transmitters. Their performance is equal to wired units.
But it is of course important from the outset to check the radio environment carefully in the premises where an installation is planned. When this is done – and the detectors are in place – the equipment will function in the same way as any normal fire alarm system. By reducing the use of energy a detector of this kind can keep working for several years before a change of battery is needed.

There are few suppliers offering wireless fire detection
So far there are not many manufacturers of alarm systems that have exploited the potential of wireless fire detectors. However there are a few manufacturers around. Two British companies, EMS and Ziton have jointly developed solutions in this field as well as Siemens of Germany.

Increasing number of features
The first detectors of this kind started to appear as early as 1995, but it is only in the last five years that this development has achieved some momentum. Available in the range of wireless applications today are conventional detectors for heat and smoke, combined detectors increasing the smoke sensitivity one step once increased temperature has been detected and combined detectors with built in sounder as well as detectors with an integral voice alarm.
In addition, one of the manufacturers, EMS, has completed its product range with a wireless manual fire alarm button (a break glass device). In other words the supply of such detectors is not a limitation.

Conservatism a restraining factor
One factor which has to a certain extent restrained development in this field is general reluctance to change amongst installers. It is a well known fact that alarm installation is a business where cables have been pulled for ages - and the cable pulling itself has been a significant source of income.
However there is also some difference in price of the detector itself. Wireless detectors contain a small transmitter which by definition makes them more expensive than traditional detectors. The price difference is however nowadays not major – wireless is usually around 20% more expensive – which makes the total cost of an installation a more accurate comparison when comparing wired and wireless installations.
At construction sites, where major cabling work is carried out anyway it is still cheaper to continue to use wired detectors. On the other hand it can be convenient to use a wireless sub controller when expanding an existing wired fire alarm system – and above all it is swift!

Planning
Installation of a wireless fire alarm system always starts with checking and measuring the environment from a radio transmission point of view at the various detection points in the premises. Often also a number of additional points are measured, particularly if there are reasons to expect future changes to the position like for example in the case of a new partition between rooms.
Sometimes it is discovered already at this stage that the signal from some detectors might be very weak, this would mean that amplifiers between detectors and control units would be installed.

The EN-54 norms applies
In terms of fire detection, manufacturers should follow the existing EN54 norms. However, there is not yet any approved standard available for radio transmission between detectors and the control panel, in spite of the fact that discussions have been ongoing for quite some time within the industry.
Previously there were also some problems with the control panels, as they were not approved for direct connection to the fire brigade. This led to the need to connect the equipment to an approved fire panel. In the majority of cases, however, this problem is on the whole solved today.

The favourite applications
An application where wireless fire alarm systems have become popular is for fire protection of listed buildings. In such environments there are often some rather major restrictions to take into consideration when installing utility devices, phone lines and alarm systems. A similar application is protection of museums. In addition wireless detectors are well suited for environments where the protected objects are spread out like theme parks with a lot of historic buildings.
Another market segment gaining momentum is in situations where there is a need to be able to move detectors from time to time. One example of an extension to an existing system is in common areas of larger blocks of fl ats where an extra level of protection is needed like in the attics.

Choice of radio transmitter
In which situations are installation of wireless fire alarms not to be recommended? This depends to some extent on which kind of radio transmitters are being used in the detectors. It is possible to use transmitters working on frequencies around 868 MHz, but these often require a booster. Another alternative is to use 169 MHz and reduce the output power in order to save battery life. However at this frequency there may be problems with radio absorption in water. Buildings with large swimming pools may thus become a problem.
Thick concrete walls and steel barriers onboard ships may also cause problems for somebody wanting to install a wireless alarm system. However in most cases the radio transmission works as long as it is contained within the shell of a vessel.

Costs are the deciding factor
Neither water nor steel shells create any definite barriers for this technology, as it is always possible to catch and boost a weak detector signal and transmit it on to the alarm panel. But it will of course add to the installation costs.

Optimal solution
If there are no aesthetics or cultural heritage considerations to take into account it is of course the troublesome cabling one wants to avoid.
Then there is of course one strictly fire technical advantage with wireless detectors. They can be placed at optimal points from a fire protection point of view – without any need for wiring considerations or limitations.