New legislation looming for visual alarm devices

The product performance required to meet the new standard has proven challenging for manufacturers to achieve, but with solutions beginning to appear on the market,
the challenge has been passed from the manufacturer to fire system designers, specifiers and installers.

Why introduce new legislation?

Up until May 2010, there was no fire industry standard that determined the light output performance criteria and installation requirements of VADs.
This gave rise to manufacturers specifying the performance of their products in an inconsistent, confusing and often misleading way. In addition, the introduction of the Equalities Act 2010 and the recommendations of BS 8300, which states that an audible alarm may be supplemented with a VAD in any area where the hearing impaired may be left alone, made a case for tighter regulation.

What is EN 54-23?

BS EN 54-23 specifies the requirements, test methods and performance criteria for VADs in fire detection and fire alarm systems. Manufacturers must now present the product’s performance data in a uniform manner so that they can be directly compared and their suitability assessed for particular applications. The standard specifies that all VADs must meet a minimum light output of 0.4 lux. The distance at which this required illumination is met, known as its coverage volume, should be quoted with the product. For example, the manufacturer of a wall mounted
VAD will be required to state a mounting height; which is a minimum 2.4m, followed by the width of a square room over which the VAD will provide coverage.

The specification code with a VAD suitable for a wall application could read: W – 2.4 – 7.5 i.e. mounted at a height of 2.4m the VAD will cover a room 7.5m2. The VAD will therefore be required to cover the volume below its mounting height. Any light going upwards will be wasted as far as this categorisation is concerned. EN 54-23 product categories available EN 54-23 allows for three product classifications: wall, ceiling and open category. If a product has been defined as a wall or ceiling product, the shape of the coverage is defined under the standard. An open class category product’s coverage shape is defined by the manufacturer.

Red or white flash?

The fire market has traditionally used a red flash to denote an alarm condition. This is quite a challenge under EN 54-23, as the light intensity drops as it is filtered through a red lens, requiring more power to achieve the required coverage. This loss can be as much as 80%. Installers and specifiers should be very aware of this when selecting a VAD. If an existing installation has VADs with red flash then the colour of the flash has to remain the same on replacements and further extensions to the system.

Specifying

Room coverage, flash colour and current consumption are the key measures when selecting a beacon. The milliamp per metre specification of a product offers a good guide to selecting the most efficient VAD possible. 
  
As well as specifying the most efficient product for an application, there are also other factors to consider. For example, some VADs, particularly open category devices that have a large coverage area, may actually be unsuitable for particular scenarios such as bathrooms, toilets and bedrooms, by far the biggest market for VADs. This is due to the glare associated with an uncontrolled dispersal pattern. BS 5839-1 2013 section 17.2e specifically warns against this: “The intensity of output of a visual alarm device should be sufficient to attract attention, but not so high as to cause difficulty with vision due to glare.” Consideration should also be given to the location and placement of the VAD; a large intrusive unit is unlikely to be favoured by the building’s architect or owner.

Summary

With the release of EN 54-23, the growth in the use of VADs is set to continue. They offer the reassurance of a visual indication to a fire alarm and help to mitigate the risk to the building occupants. Fully automated and highly reliable, used as part of a comprehensive fire detection system, VADs remove any human error associated with buddy systems that rely on human interaction or the requirement to ensure that portable tactile devices are working and that the batteries are charged. The new standard enforces a specific illumination level, ensuring that any visual alarm is meaningful and inclusive to all.