Smoke alarm types

The NSWFB welcomed the Government initiative which provided for the compulsory installation of smoke alarms in all places where people sleep. The legislation provides for a minimum level of protection howeve the NSWFB recommends that a higher level of protection be considered such as a hard wired, interconnected smoke alarm system containing a combination of photoelectric and ionisation type detectors. Where battery powered smoke alarms are installed the NSWFB recommends that a combination of photoelectric and ionisation type smoke alarms be installed. Where only one smoke alarm is installed per level the NSWFB recommend that this be installed between the sleeping areas and the living areas. As this is the path of travel from sleeping areas to egress it is recommended this should be a photoelectric type smoke alarm.

The legislation requires that owners of affected premises ensure that buildings are equipped with smoke alarms that meet Australian Standard AS3786 and therefore are marked as:

Approved to AS3786
Accredited to AS3786, or
SSL (Scientific Services Laboratory) listed. Scientific Services Laboratory (SSL) which is a part of the Australian Government Analytical Laboratories.

The two main ways that smoke alarms detect smoke are photoelectric and ionisation. Research indicates that photo-electric smoke alarms may be more effective at detecting smouldering fires and fires starting in areas remote from smoke alarms, and that ionisation smoke alarms may be more effective at detecting flaming fires. Both types of fires may occur in buildings where people sleep. The NSW Fire Brigades recommends where possible that photo-electric smoke alarms are installed in paths of travel between sleeping areas and exits to the open air or to common corridors.

Some smoke alarms can also monitor levels of carbon monoxide. These alarms generally use sound to alert occupants of fire. Other methods of alerting occupants include alarms with emergency lights, alarms for the Deaf and Hearing Impaired and special models for kitchens and relocatable homes.

Photoelectric
Ionisation
Carbon monoxide
Alarms for the Deaf and Hearing Impaired
Special models for kitchens and relocatable homes
Heat alarms

Photoelectric smoke alarms

Photoelectric smoke alarms 'see' the smoke. They detect visible particles of combustion, eg smouldering cigarette smoke. They respond to a wide range of fires, but they are particularly responsive to smouldering fires and the dense smoke given off by foam filled furnishings or overheated PVC wiring.

Advantages

Good for smouldering fire and dense smoke
Not as prone to cooking nuisance alarms as ionisation alarms
Contain no radioactive material
Suitable for general use

Disadvantages

Slightly more expensive than ionisation alarms
Nuisance alarms can occasionally occur from dust and insects
They must be kept clean

Ionisation smoke alarms

Ionisation smoke alarms 'feel' the smoke. They detect invisible particles of combustion, eg from cooking toast. They activate more quickly for fast, flaming fires with little visible smoke.

Advantages

Slightly cheaper than other types of smoke alarms
Very good with fast flaming fires with little visible smoke
Less prone to false alarms caused by dust and steam
Suitable for general use

Disadvantages

Can be susceptible to nuisance alarms if placed too close to cooking
May be slow to respond to slow smouldering fires
Contain a very small amount of radioactive material

Carbon monoxide alarms

Carbon monoxide alarms are not smoke alarms and do not satisfy the legislation. They may be used in addition to smoke alarms for increased warning.

You can't see it, taste it, or smell it, but low levels of carbon monoxide can make you sick and high levels can kill. Carbon monoxide is a by-product of combustion. Appliances, such as heaters, ovens, and cooktops which burn gas, oil or wood emit carbon monoxide.

While carbon monoxide alarms are widely used overseas to check the safe operations of central heating systems, they are yet to be commonly used for the detection of fire in the home.

Disadvantages

One disadvantage of carbon monoxide alarms is that they are more expensive than photolectric alarms.
Carbon monoxide alarms only have a lifespan of approximately 5 years.

Carbon monoxide alarms are in addition to a working ionisation or photoelectric smoke alarm. They should not be used as the sole smoke alarm.

Alarms for the hearing-impaired

There are specialised smoke alarms available for people who are Deaf or have a hearing impairment. These have a flashing strobe light and/or a vibrating pad that can be placed under the pillow which activate when the smoke alarm sounds and are designed to interconnect with conventional audible alarms in different locations within the home. If one of the alarms senses smoke, all alarms will sound, the strobe will flash and the vibrating pad will operate.

At present there is no Australian Standard (AS) that applies to smoke alarms for hearing impaired people. If the code number AS3786 appears on a smoke alarm for hearing impaired people, it refers only to the smoke alarm sensing unit and does not include the flashing strobe light or the vibrating pad.

People who wish to purchase smoke alarms for the hearing impaired should contact the relevant associations in their state for information on where they can be sourced or visit http://www.betterhearingsydney.org.au/content/view/63/53/

View our Smoke Alarms for the Deaf and Hearing Impaired factsheet

Special models for kitchens and relocatable homes

Smoke alarms specifically designed for confined areas like relocatable homes and kitchens are available from hardware and specialty stores.

Heat alarms

There are some areas in the home where smoke alarms may not be suitable, eg kitchen. In these areas the legislation allows a heat alarm to be used in lieu of a smoke alarm.

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