EmailUnderstanding different types of smoke detectors
Reviewers agree on one thing: The best smoke alarms can sense both types of fires (high-flame and smoky) with equal effectiveness, and that means either buying a smoke detector with both an ionization sensor for flames and a photoelectric sensor for smoke or using two separate smoke alarms to achieve the highest degree of safety and preparedness.
Reviews show that smoke detectors equipped with just a single sensor are not nearly as effective as those with dual sensors. Ionization models -- the most popular (and cheapest) type of smoke alarm -- are very good at signaling the presence of a fire with high flames, but are much slower to detect smoky blazes. Conversely, photoelectric smoke alarms are much more effective at detecting smoky fires, but do not fare as well in high-flame fires.
Ionization smoke detectors use a harmless radioactive source that establishes an electric current in the detector chamber; when smoke enters the chamber, the unit senses the change in electrical current and triggers the alarm. Photoelectric smoke alarms activate when the smoke is dense enough to deflect a beam of light. The best smoke detectors, reviews say, employ a combination ionization/photoelectric sensor that can detect both flaming and smoldering fires with equal speed and accuracy. This is no small matter: Smoke detectors are meant to save lives and protect your home, and experts say they improve your chances of surviving a fire by 50 percent.
The least expensive smoke detectors are built to detect either smoke or fire, but not both, so you'll have to buy two to ensure complete coverage. Dual-detection models avoid this need. Experts say you should look for the following when choosing a smoke detector:
- Choose a smoke detector that uses a combination ionization/photoelectric sensor and is able to detect both flaming fires and slow, smoldering fires with equal speed and accuracy. If you choose not to use a dual-sensor model, you'll need both ionization and photoelectric smoke detectors installed in your home.
- Only consider a smoke alarm that meets Underwriters Laboratory (UL) standards. Most, but not all, models do.
- Smoke detectors should have a test button to ensure that alarms and sensors are operating correctly. This test button should be used at least monthly to test an alarm's electronics and battery.
- Make sure the smoke alarm has a hinged or removable cover for easy cleaning. Too much dust can cause a sensor to fail. Most smoke alarms can be vacuumed out to prevent dust buildup.
- Check that the smoke detector has a feature that allows you to silence false alarms. This can help avoid the temptation to disable the unit.
According to experts, all smoke detectors have a lifespan of about 10 years, so it's important to replace old detectors each decade. Smoke alarms that use nine-volt batteries should get fresh batteries at least annually. Experts suggest replacing the batteries when you change your clocks each year for the start of daylight-saving time.
Experts recommend a smoke detector on each floor of your home and outside each bedroom, or inside the bedroom if you sleep with the door closed.