Do your insureds have the correct smoke detector?

Along with the semi-annual ritual of replacing smoke detector batteries, now your insureds need to know what kind of smoke detectors they have. There are two types of smoke detectors, ionization and photoelectric, and they do not respond the same in smoke or fire situations.

How do smoke detectors work?

A smoke detector is an electrical circuit that can be interrupted by particles in the air. The electricity runs through a chamber where there is a gap between two electrodes. The electricity continually crosses this gap as long as the power source is live. The microchip monitors the flow of electricity. If the flow is interrupted, the microchip triggers the alarm.

A fire or any smoke-emitting situation sends particles into the air that eventually disrupt the electrical flow in the smoke detector and the alarm sounds.

Ionization smoke detectors use an ionization chamber and a source of ionizing radiation to detect smoke. Photoelectric smoke detectors have a light and a sensor positioned at 90-degree angles to one another. Normally, the light from the light source shoots straight across and misses the sensor. When smoke enters the chamber, the smoke particles scatter the light and some amount of light hits the sensor. The sensor then sets off the alarm.

Which smoke detector is best?

Ionization smoke detectors are less expensive and are used in approximately 80% of residences in the United States. A recent study conducted by WTHR channel 13, a television station serving the Indianapolis, Indiana metropolitan area in conjunction with the Indianapolis Fire Department showed that the ionization smoke detector responds much slower to smoldering fires than do the photoelectric detectors.

Tests have shown that photoelectric and dual sensor alarms (the ones which contain both ionization and photoelectric technology) provide up to 26 minutes of extra warning time in smoldering fires. That extra time could allow your insured’s family time to escape before the house is filled with life-threatening smoke and carbon monoxide.

WTHR recently conducted an aquarium test using a 29-gallon glass aquarium, an ionization smoke detector, a carbon monoxide (CO) detector, some polyurethane foam (commonly used in furniture cushions) and a soldering iron in order to create a slow, smokey fire inside the closed aquarium. After eight minutes, the tank was so smoke-filled that the only visible items were those up against the inside wall of the aquarium. At that time the carbon monoxide detector began emitting its alarm. The ionization smoke detector had not sounded after 25 minutes into the test, when the CO detector was at its maximum 999 parts per million, which is a deadly level. At that point, a photoelectric smoke detector was dropped into the tank and it sounded the alarm within five seconds. (The ionization smoke detector was tested before it was placed in the aquarium and after it was removed to confirm that it was a working smoke detector.)

Smoke alarm companies advertise that their smoke detectors meet strict federal standards and that both types of smoke detectors allow consumers time to escape most fires.

How do you tell what type of smoke detector your customer has?

• If you do not see any symbols on the unit, most likely it is the ionization type. Those are usually marked with the letter “I” or other symbols.
• Photoelectric smoke detectors may have the word “PHOTOELECTRIC” printed on them, or the letter “P”, or a “blue symbol”.
• If you see “dual sensor”, that means the smoke detector has both photoelectric and ionization capabilities. This type provides maximum protection and the greatest escape time.
• While you are checking to see what type of detector your customer has, test the batteries.
• Smoke detectors should be replaced every 10 years and batteries should be checked twice a year.
• A smoke detector should have a test button. When the button is depressed, the audible alarm sounds the warning signal. If your insured has a hearing impaired person in their house, recommend the installation of a hearing impaired smoke detector. These are special units that feature a powerful strobe light to alert the hearing impaired in the event of a fire. Some smoke detectors also use the technology of a remote control for testing and/or silencing the unit.
• Recommend installation of a smoke detector in the garage and the attic. Many household fires begin from a electrical wiring (attic) or flammable substances stored in the garage.
• If the home is multi-level, consider recommending the installation of smoke detectors on each level.

It is also a good idea for your insureds to have fire extinguishers and carbon monoxide detectors in their home. Smoke detectors save lives. Photoelectric or dual sensor alarms in your insured’s home provides the most effective resource for survival in a fire.

Carol Liming
Underwriter II
NAMIC Insurance Company
climing@namic.org