Aico RFD manual Quality & Compatibility, Grade System, Levels of Protection Categories of System

QUALITY & COMPATIBILITY

The quality of equipment installed is a factor that needs to be carefully considered. The Code states that, in general, all components should conform to relevant British Standards and should have undergone type testing to those Standards. Suppliers should preferably have approval to a recognised quality approval scheme such as the relevant BS EN ISO 9000 series standard. If no British Standards apply, reasonable care should be taken that components are fit for the purpose intended.

The Code recommends that all individual system components should be mutually compatible.

Conformance to the relevant British Standard is no guarantee that the components of a system will be compatible. Consequently, this should be confirmed at the design stage.

THE GRADE SYSTEM

Relates to system engineering not level of protection.

BS 5839: Pt.6 grades fire detection systems from Grade A down to Grade F. Generally speaking, the greater the fire risk and the more demanding the application, the more comprehensive the system needs to be.

•Grade A - Fire detection system incorporating control and indicating

equipment to BS EN 54-2, and power supply to BS EN 54-4, installed to BS 5839: Pt.1 with some minor exceptions

•Grade B - Fire detection and alarm system comprising fire detectors (other than smoke alarms), fire alarm sounders and control and indicating equipment to either BS EN 54-2 (and power supply to BS EN 54-4), or to Annex C of BS 5839: Pt.6

•Grade C - System consisting of smoke detectors and sounders (which may be smoke alarms) connected to a common power supply, comprising normal mains and stand-by supply, with central control equipment

•Grade D - System incorporating one or more mains powered smoke alarms (and heat alarms if required) each with an integral stand-by supply

•Grade E - System of mains powered smoke alarms (and heat alarms if required) with no stand-by supply

•Grade F - System of one or more battery powered smoke alarms (and heat alarms if required)

The changes from the previous edition are relatively small: Grade A & B now refer to the latest European Standards and there are minor changes in requirements. Grade C now requires central control of the system. Grades E, D & F now have reference to heat alarms in addition to smoke alarms.

Concerned by problems with battery powered units in Grade F, the prescriptive advice in the Code now recommends a minimum five year battery life and batteries that are secured so that a special tool is required to remove them for use in tenanted single storey properties.

As the overwhelming number of residential applications in the UK will fall into the D to F categories, this is the area on which this guide will naturally focus. If you are particularly interested in unusual grades of protection, you are invited to look further at the relevant clauses of the Code.

Of course, installers and specifiers may install a system with greater safety features than laid down in the letter of

the Code. For example, rather than a Grade E system landlords might think it prudent to install a Grade D system instead. This is especially true considering the many restrictions that apply to the use of Grade E systems.

LEVELS OF PROTECTION

CATEGORIES OF SYSTEM

This was previously referred to as ‘type’ of system. It relates to the level of protection afforded by the system.

Within the A - F grades defined earlier, the Code identifies three different categories of protection:

•LD1 - A system installed throughout the dwelling, incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling, and in all rooms and areas in which fire might start, other than toilets, bathrooms and shower rooms

•LD2 - A system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling, and in all rooms or areas that present a high risk of fire

•LD3 - A system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling

Apart from the change of name, there are no changes to the ‘Categories’ from the previous version of the code.

It is noted that an LD3 type system is intended to protect escape routes for those not directly involved in the fire and may not save the life of anyone in the immediate vicinity of the fire.

The Code also features two grades of protection for property - PD1 and PD2. Briefly, PD1 offers comprehensive coverage of all areas, while a PD2 system includes detectors in only those areas where there has been judged a fire risk. Only by quoting Grade and Category can a meaningful and effective alarm system be specified, e.g. Grade D, Category LD2.

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