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. 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
unsuitable e.g. kitchens, boiler rooms, garages. However, they must always be used
interconnected to smoke alarms –
do not use in isolation
. (They will typically go into
alarm when the temperature reaches approximately 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
correctly. 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 is a class A2 device and will alarm between 54°C and
70°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
consumer unit/circuit breaker connection. As with previous point above, if in
doubt, consult an electrician or your Landlord.
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