New legislation for Visual Alarm Devices looming
15Dec
January 2014 saw the introduction of EN 54-23, a new standard for fire alarm beacons.
The standard dictates that all beacons manufactured for fire alarm use and sold for fire alarm applications in the E.U, must be CE certified using the new standard. It will affect architects, building owners, fire equipment installers, risk assessors and anyone responsible for fire system design.
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 BS8300, 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 EN54-23?
BS EN54-23 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 suitability assessed for particular applications.
The standard specifies that all VADs must meet a minimum light output of 0.4lux. 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 7.5m square. 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.
Examples of dispersal and coverage areas for each product category, and their corresponding specification code, are shown below:
Wall category: w- x – y
x is the maximum mounting height (minimum is 2.4m), y is the width in square meters of the square volume coverage (to a minimum level of 0.4lux) when the device is mounted to the wall at height x. A typical example may be: W – 2.4 – 7.5
Ceiling category: c-x-y
x is the maximum mounting height:- 3, 6 or 9m, y is the diameter in meters of the cylindrical coverage volume (note: the protected space sits within the cylindrical volume and ensures that all areas meet the required illumination of 0.4 lux). A typical example may be: C – 3 – 7.5
Open category:
Open class devices do not conform to either the Wall or Ceiling category. However, they still need to meet the required illumination of 0.4lux over their specified area.
Manufacturer’s specification will include: -
• Mounting position and orientation
• A minimum and maximum mounting height
• The shape, dimensions and orientation of the coverage volume
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 per cent. Installers and specifiers should be 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.
Eaton’s Fulleon business has managed to develop a red flash option that performs equally to a white flash, meaning no compromises have to be made when specifying a fire 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. This is due to the glare associated with an uncontrolled dispersal pattern.
BS5839-1 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 architect or owner.
System considerations
If VAD’s are the chosen solution, consideration should be given to any impact they may have on the system driving them. Additional power may be drawn from the circuit wiring and control panel, especially if the VAD is covering a relatively large area. However, these factors can be greatly minimised if a careful design approach is taken. For example, fitting the correct number of VADs to cover an area is highly recommended. Careful placement and positioning will ensure a good coverage, thus reducing the number of VADs required.
Has consideration been given to ambient light levels? Referring to and implementing the multiplication factors in the ambient light tables in COP 0001 can significantly impact on the number of VADs required, and thus the loading on a system. If the ambient light levels are subdued, the number of VADs fitted can be significantly reduced.
Are all VADs placed in areas where they will have a significant benefit? Sanitary accommodation such as toilets, bathrooms and sleeping accommodation may be considered to be essential locations during a risk assessment, but what about other areas? It may be that areas outside these categories could have a reduced number, if not complete omission of VADs.
Are the VAD’s suitably rated?
It is certainly noted that some manufacturers of VADs are going for the ‘mines brighter than yours’ approach. While this may make a good marketing headline, the question has to be asked about why? A VAD only needs to provide the appropriate amount of illumination to be effective. If the coverage is overrated for the requirement, this would simply waste power and put undue loading on the system or control panel and could even possibly lead to issues of glare. A balance and appropriate approach is required to ensure that the system is adequately rated, but not over-designed.
The design of addressable VAD systems certainly requires greater consideration over their conventional equivalents. The current available from an addressable control panel is usually limited by the bespoke addressable protocol. However, it is possible to have a limited number of VADs hooked directly onto the system wiring, and where this is not possible, other solutions can also be explored. Many system designers or suppliers can offer ‘power interface controllers’ that can feed locally sourced power to a device on the address loop. Often, they also have the advantage of being able to supply more than one VAD device and can take a significant load off the fire detection and alarm panel. While this can result in some additional cost to the system, this can sometimes be balanced against the resulting savings, if it allows for the fitting of reduced gauge wiring. However, as lighting technology improves in the next few years, especially surrounding the developments of LED chips, the need for these additional interfaces should be reduced.
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 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.
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