Aico Residential Fire Detection RFD - Manual (Page 14)

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The Code also looks at a third type of
alarm - heat. More emphasis is placed
upon the use of heat alarms than
previously. The Code recommends that
they should comply with BS 5446: Pt.2 and
suggests they be used where nuisance
alarms from other sensor types are a
concern. In new build properties heat
alarms are now recommended both in
the kitchen and possibly the principal
habitable room, such as the living room.
Domestic heat alarms require less
maintenance than any other type of unit
and aren’t prone to false alarms caused
by contamination or smoke caused by
cooking. For this reason, heat alarms were
originally specifically designed for use in
kitchens or garages, where other alarms
are less reliable and more likely to go off
accidentally. Fire deaths from fires
originating in the kitchen are sadly
increasing and such fires can often cause
extensive property damage and,
therefore, landlords might consider them
good insurance. Heat alarms are
generally less sensitive than smoke alarms
and must not be used in circulation areas.
BS 5839: Pt.6 recommends that heat
alarms have a role to play in Category
LD2 systems.
The Code acknowledges that a mix and
match approach to systems is sensible,
installing different detector types in areas
where they are most effective.
For more information on the different
types of detection technology
available, please see the product
information section towards the back of
this guide.
CO and Multi-sensor fire alarms are
introduced into the 2004 Code. CO fire
alarms are specifically designed for
detecting carbon monoxide produced
in a fire and can respond quicker than
heat detectors, but are almost always
slower to respond than a smoke alarm.
The type used for detecting CO gas
from faulty appliances etc are
designed to respond at much higher
levels of CO. Consequently, CO alarms
conforming to BS 7860 or BS EN 50291
should not be used as CO fire alarms. It
is not likely that CO fire alarms have a
significant role to play in domestic
dwellings at present.
A Multi-sensor alarm is defined in the
standard as a “fire detector that monitors
more than one physical and/or chemical
phenomenon associated with fire”. An
alarm consisting of an optical sensor and
a heat sensor, or one containing an
ionisation sensor and a CO sensor, would
fit this definition. The benefit of this type of
detector is that a broader response to
different fire types can be achieved with,
often, a reduction in false alarm
problems. At present there are no
suitable types available for use with
smoke alarm systems.
CHOOSING WHICH
ALARMS TO USE
BS 5839: Pt.6 also looks in depth at the
different kind of fire alarm sensors on offer.
Sensibly, it points out that there is no single
type of alarm that is most suitable in all
cases and the final choice of which type
of alarm to use will depend on individual
circumstances.
In general, these circumstances are the
desire to afford the earliest possible
warning of a fire and the need to
minimise false alarms.
This means, in plain English, that the
most suitable alarm should always be
installed - and not just the cheapest
option. This is a point that landlords
cannot overlook in meeting their ‘duty
of care’ obligations.
The Code recommends that optical
smoke alarms should be installed in
circulation spaces, such as hallways
and near kitchens. They should also
be considered in areas where a likely
cause of fire is ignition of furniture or
bedding by a cigarette.
Ionisation alarms are recommended
more for use in living rooms or dining
rooms, where a fast burning fire may
present a greater danger than a slow
smouldering one, though due
consideration needs to be given to the
potential for false alarms. The new 2004
Code does not recommend the use of
ionisation types in escape routes.
SINGLE STOREY DWELLING
Optical or Ionisation smoke alarm as best suited for the particular circumstances
Optical smoke alarm
Smoke or heat alarm as best suited for the particular circumstances
Heat alarm
Do not install smoke or heat alarms in bathrooms, shower rooms or toilets