b. Alarm Types
•
Ionisation (Ion) alarms
are the most common type and provide early detection against
fast flaming fires and other fires. Most suitable for dining and living room areas. Ion
alarms contain 0.9 microcurie of Americium 241, a radioactive material. UK Home Office
and BS5839 Pt6 recommend however, that optical alarms are also used especially in
locations where steam or cooking fumes, from a nearby room could cause nuisance
alarms.
No one type of alarm is considered suitable for all locations
.
•
Optical (Photo-Electric) alarms
are increasingly used and are less prone to nuisance
alarms
from cooking fumes. They are therefore the recommended type in BS5839 Pt6, for fitting
near kitchen areas and on escape routes/circulation spaces.
•
Heat alarms
are for use in areas where Ion or Optical smoke alarms would be unsuit-
able e.g. kitchens, boiler rooms, garages. However, they must always be used intercon-
nected to smoke alarms –
do not use in isolation
. (They will typically go into alarm when
the temperature reaches 57°C.) Suitable for new Building Regulations applicable
1/7/2000 regarding use in kitchens.
4. How to Operate/Test the Alarm
a. Operation and L.E.D. Status
• When your alarm is correctly installed to the mains supply, the green L.E.D. light will be
on. The red L.E.D. will blink every 30-40 seconds to indicate the sensor is operating cor-
rectly. If the alarm senses products of combustion, its 85dB horn will be activated.
The
red L.E.D. will flash rapidly on the alarm sensing smoke/heat.
(Other interconnected
alarms will also sound to warn those in other parts of the property.) This will continue
until the sensor chamber is clear.
In the case of a heat alarm, it will be triggered when the temperature reaches 57°C and
return to its standby mode when the temperature drops to normal levels. On optical
alarms if the red L.E.D. blinks every 30-40 seconds and the alarm chirps inbetween, it
indicates failure of the sensing chamber.
Regularly check and ensure that the green L.E.D. is lit – if not, check the con-
sumer unit/circuit breaker connection. As with previous point above, if in doubt,
consult an electrician or your Landlord.
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