Smoke detectors have significant differences

Test shoes photoelectric technology responds faster to smoldering fire

All smoke detectors are not the same. Tests show the type of technology used in the detector can make a big difference in how quickly it sounds in different types of fires.

There are two types of technologies used in residential smoke alarms. Ionization is generally faster at detecting flaming fires, while photoelectric devices are generally quicker detecting slower smoldering fires.

"In my opinion, an ionization smoke detector should never be used alone in a home as a sole mean of detecting fire," said Dr. B. Don Russell, professor at Texas A&M's Department of Electrical and Computer Engineering. "Unfortunately, 90 percent of all the smoke detectors in residences in the U.S. are ionization smoke detectors."

Russell has been testing and sounding the alarm on ionization detectors for years.

"In many of the fires we have staged in a test residence, we have found that the photoelectric detectors will go off 20 minutes, 30 minutes, even 40 minutes or even an hour before the ionization detectors," he said.

Good Morning America worked with the Northeastern Ohio Fire Prevention Association on a demonstration.

They bought six new alarms from two leading manufacturers, including two ionization, two photoelectric and two combination alarms which use both technologies.   They mounted them in a house that was set for demolition.

When they set a contained, fast blazing fire, the ionization detector went off after 45 seconds. The photoelectrics sounded after four and five minutes.

But when they started a smoldering fire in a piece of furniture, the results were very different.

The first photoelectric alarm sounded 12 minutes and 15 seconds after the first sight of smoke.  The other photoelectric sounded a minute and a half later.

The combination, or dual-sensor alarms, went off approximately nine minutes later.

After an hour and ten minutes, the smoke was so thick and the conditions becoming so dangerous, the firefighters called off the demonstration. Neither ionization detector had gone off.

"The real danger to people tends to be at night when people are sleeping, and you have a slow fire that develops and throws off a lot of smoke and a lot of toxic gases," Russell said. "If you have a slow-developing fire in furniture, someone drops a cigarette in a couch as an example, you can fill an entire house full of smoke and toxic gases and many people will die in their beds because they never get a warning."

Russell's advice to consumers is to use both ionization and  photoelectric detectors  or buy combination detectors that have both types of sensors in the same unit.

"People need a lot of smoke detectors in their house," he said. "Don't depend on one or two. Have one in every bedroom, every hallway, use a lot of different smoke detectors."

Homeowners can tell what type of detector they have by either looking at the small print on the packaging or on the back of the detector. The letter, "i" means it's ionization, and the letter "p" means photoelectric.

Two of the biggest alarm manufacturers told Good Morning America that their alarms meet industry standards, but for optimal protection, they recommend consumers use both types of alarms.

For a list of recent stories Marilyn Moritz has done, click here.

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