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HomeMy WebLinkAboutIAFC Smoke Detector Fact SheetIAFC Smoke Detector Fact Sheet Compiled by the International Association of Fire Chiefs Distributed by the Iowa City Fire Department & Housing Inspection Services Is there more than one type of smoke detector, and what is the difference? There are two types of smoke detectors for homes. One type is called an ionization de-tector because it monitors “ions,” or electri-cally charged particles. Smoke particles en- tering the sensing chamber change the elec-trical balance of the air. The detector’s hornwill sound when the change in electrical balance reaches a preset level. The othertype of detector is called photoelectric be-cause its sensing chamber uses a beam of light and a light sensor. Smoke particles entering the chamber change the amountof light that reaches the light sensor. The detector sounds when the smoke density reaches a preset level. Is one type better than the other? The ionization detector responds faster tosmall smoke particles, while the photoelec-tric type responds faster to large smoke par- ticles. As a rule of thumb, fast-flaming fires produce more small smoke particles andsmoldering fires produce more large par- ticles. Thus, the response time of the two types of detectors will vary, depending onthe mix of small and large smoke particlesin the fire. But test results show that the differences in response time are small enough that both types provide enough timeto escape. What is more important, the type of de-tector or the number of them?The number of detectors is more important than the type. Installing several smoke de-tectors of each type will provide better cov-erage in the extreme cases of long-term smol- dering or fast flaming fires. But since bothtypes of detector will respond in time toescape, the most important thing is to in- stall enough detectors in the proper loca- tions. How effective are smoke detectors? Residential fire deaths have decreasedsteadily as the number of homes with smoke detectors increased. Reports from the Na- tional Fire Protection Association on resi-dential fire deaths show that people have nearly a 40-50 percent better chance of surviving a fire if their home has the recom-mended number of smoke detectors. Should I replace my smoke detector?Smoke detectors that are 10 years old arenear the end of their service life and should be replaced. A smoke detector constantly monitors the air 24 hours a day. At the endof 10 years, it has gone through more than 3.5 million monitoring cycles. After this much use, components may become lessreliable. This means that as the detectorgets older, the potential of failure increases. Replacing them after 10 years reduces this possibility. My detectors are wired into my electri-cal system. Do I need to replace them as often as battery-operated detectors? Yes. Both types of detectors are equallyaffected by age. How many detectors should I have?The average sized home or apartment needs more than one smoke detector. The exact number depends on the number of levels inthe home and the number of bedrooms. National fire safety standards recommend a minimum of one detector on each level ofthe home, one detector outside the bed-room area, and one in each bedroom. The detector that is placed outside of the bed-room area should be installed near enoughto be heard at night through a closed bed- room door. continued on other side Detectors are available with both types ofsensors in the same unit, but they are moreexpensive than models with a single sen- sor. If the choice is between having onlyone of each type or having more of thesame type, more detectors is the better choice. My detector goes off when I cook. How can I stop this? Smoke detectors are designed to be verysensitive so they will alert occupants to afire in time for them to escape. If a detector regularly responds to smoke from cooking, there are several options for handling thisproblem. One way is to use heat detectors instead in the kitchen. Another way is to move the smoke detector farther away, giv-ing the smoke a chance to dissipate. Mov-ing a ceiling-mounted detector to a wall can also reduce nuisance alarms. However, thiswill also make it a little slower to respond toa real fire. If the detector is the ionization type, an-other option is to replace it with a photo- electric. This detector is less sensitive to smaller smoke particles and thus is less af-fected by cooking smoke. How can I test my detector?Every smoke detector comes with a testbutton. We recommend that people test their detectors regularly, at least once a month. Should I use real smoke to test my de- tectors? This is not recommended because the burn- ing objects used to create the smoke might cause a fire. Some stores sell pressurized cans of simulated smoke for this purpose. When using this product, follow the manufacturer's instructions. How important is it to clean my detec- tors? Cleaning is important and easy. Just vacuum the detector once a month. This will keep the openings to the sensing chamber free of dust, residue from cooking vapors and insects. What about changing batteries? Smoke detector batteries should last at least one year under normal conditions. The main reason that smoke detectors don’t work is because people remove the batteries, e.g., to stop the low battery signal or a nuisance alarm, and forget to replace them. When a battery reaches the end of its service life, the detector will give a short beep every minute or so. It is easy to remove the bat- tery and then forget to replace it. The best way to prevent this is to replace batteries at the same time each year before the low battery signal begins. The IAFC suggests replacing smoke detector batteries when re-setting clocks for the fall time change. hisadmin\page\detector.p65 Have Questions? Fire Marshal 356-5257 Housing Inspection 356-5130