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b. Alarm Types
• Ionisation (Ion) alarms are the most common type and provide early detection,
especially against fast flaming 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
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 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 about once a minute to indicate the sensor is
operating correctly. If the alarm senses products of combustion, it’s 85dB horn
will by 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 it’s 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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