A debate has raged over which type of smoke alarm gives consumers the best protection against fires—alarms that have an ionization sensor or those that have a photoelectric sensor.
Ionization smoke alarms provide earlier warnings during flaming fires than do those that have a photoelectric sensor. Photoelectric smoke alarms provide earlier alerts during smoldering fires. Residents of Maine, Massachusetts and Vermont, as well as a few cities, now are required to install photoelectric smoke alarms in their homes, and sporadic reports indicate that those types are better. However, Iowa requires smoke alarms that have both types of sensors, and we found that only one type of smoke alarm isn’t enough.
“You need both, because you don’t know what kind of fire you’re going to have,” says Judy Comoletti of National Fire Protection Association (NFPA). That remains true despite the fact that photoelectric smoke alarms respond minutes faster in smoldering fires than do ionization smoke alarms but only seconds slower in flaming fires, according to National Institute of Standards and Technology (NIST).
The approval of new UL test standards to certify smoke alarms is about to change the market for smoke alarms significantly. The likely outcome, according to Tom Cleary of NIST, who has been involved in the development process of the new UL test standards, is that smoke alarms that are equipped solely with ionization sensors will disappear after the new test standards take effect. That should happen within 2–3 years.
Such a disappearance will mean that consumers will have to spend more to get fire protection for their homes. Although we found seven ionization models that cost less than $10, you typically have to spend at least $18 to get a photoelectric smoke alarm, and none costs less than $10.
“Low-priced models will be a thing of the past,” admits Karen Yaggie of manufacturer Universal Security Instruments. “None of us will be able to make a $5 smoke alarm anymore.”
Cleary also predicts that the cost to make smoke alarms will go up after the new test standards are enforced. He couldn’t predict, however, whether manufacturers would pass those increased costs on to the consumer.
UL TESTING. Manufacturers could begin to certify their smoke alarms under the new test standards voluntarily before the end of 2016, and the new standards could become mandatory for UL certification within 2–3 years, John Drengenberg of UL tells us. The test standards aim to filter out nuisance alarms that result from cooking and to ensure that all smoke alarms provide early alerts of fires.
To filter out nuisance alarms, Drengenberg explains, the new UL standards test to see how smoke alarms perform when hamburgers are broiled or pan-fried and when bread is toasted. Drengenberg says these cooking techniques produce the broadest variety of particle sizes—big to small. That’s why the new test standards will be a challenge for photoelectric alarms, which are more sensitive to the big particles that are typical of smoldering fires, and ionization alarms, which are more sensitive to the small particles that are produced by flaming fires.
Toasting bread, for instance, produces small particles, which trigger unwanted nuisance alarms more readily in ionization sensors.
Meanwhile, the new early-alert test standards use different techniques to burn polyurethane foam to see how quickly the smoke alarms react. Drengenberg says the tests are designed to reflect the more common use of polyurethane foam in today’s upholstered furnishings, as well as the more open floor plans that are found in new homes, which allow fires to spread faster than when walls between spaces contain the spread of flames.