Trial by Fire: See which smoke alarms work the quickest when seconds count

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Fires break out in more than one thousand homes across the country every 24 hours, killing seven people each day.

Smoke alarms are designed to save lives, by warning us when fires ignite in our homes -- but there are some important things to keep in mind when buying and installing your smoke alarms that most people don't know.

"Having both ionization and photoelectric alarms are essential to our safety," said Einar Jensen, a fire safety educator with the South Metro Fire Department.

As Jensen explains, there are two kinds of fires -- flaming fires and smoldering fires.

Flaming fires are typically caused by open flames igniting household materials, like "a candle igniting a curtain," said Jensen.

On the other hand, smoldering fires, which research shows are the deadliest kind, don't create flames. They are typically caused by smoking materials, like cigarettes, that are improperly put out.

Smoldering fires can also go unnoticed, because they make less noise, and take longer to ignite.

"We have an ionization alarm, which detects flaming fire, and we have a photoelectric alarm, which is better for a smoldering fire," Jensen explains.

The problem is that most shoppers don't know the difference and typically only buy one kind of alarm.

While the biggest smoke alarm manufacturers don't release annual sales, reports indicate that most homes are equipped with only one kind of alarm -- Ionization alarms, which tend to be more popular because they are usually cheaper.

To illustrate the difference in the alarms, we staged an experiment, with the help of the South Metro Fire Department.

We ignited both flaming and smoldering fires, to test ionization and photoelectric alarms, as well as "dual-sensor alarms," which feature both kinds of technology.

For the flaming fire, we set up the three alarms in a structure built meant to simulate a typical room inside a home, with a couch inside. After igniting some paper in a metal bin inside the structure, we started our clock.

As expected, the ionization, flame-detecting alarm went off first -- at 28 seconds.

Then, at 39 seconds, the dual sensor, with both kinds of technology began beeping.

Then, finally at 51 seconds, the photoelectric, smoke-detecting alarm went off.

That all three alarms went off within a minute was a good sign, according to the experts.

"We saw the technology work the way it is supposed to," said Jensen.

To simulate a smoldering fire, we sealed all three alarms inside an aquarium, with a heated soldering iron pressed against a pillow. Once smoke was visible inside the tank, we started our clock.

It took just over five minutes, (5:14) for the photoelectric alarm, designed to detect smoke, to sound.

The dual alarm, with both kinds of technology, went off next -- at five minutes, 58 seconds.

Then, at 6:23, the ionization, flame-detecting alarm rang. That's more than a minute from when the first alarm went off, precious seconds you'll need to get out of your home safely, according to Jensen.

"We need that early announcement that we need to get out," said the fire safety educator.

While the ionization alarm was triggered after about seven minutes during our smoldering fire, in other simulations, it's shown to take much longer before going off.

Einar tells us these results are no surprise, because ionization alarms simply aren't designed for smoldering fires, meaning having both kinds of technology is crucial.

"The takeaway from this is that we need both kinds of technology protecting our families," said Jensen. "We need photoelectric alarms for the smoldering fire; we need ionization alarms for that flaming fire."

"We humans make mistakes and we're careless," Jensen added. "We leave candles burning, we discard cigarettes... When we make bad choices, fires happen, so we need that defense in there, to make sure that when we do mess up as humans, we have technology that's going to help us, help save our lives."