Are Your Smoke Alarms Keeping You Safe?
By Brian Welch
Inspector/Firefighter
Chaffee County Fire Protection District
Imagine what it would be like for you and your family were to wake up in a house filled with smoke and your smoke alarms are not sounding. After getting to safety and calling 911, you start remembering how, just last month, you changed the batteries and cleaned the alarm. Unfortunately, this situation happens often, and it doesn’t always end up with everyone making it to safety.
Smoke alarms are commonly thought of as the little white alarms that tell you when Dad has burned the bacon. Some will know a little more about these contraptions such as the fact that batteries should be changed twice a year. Or that you should have one in each sleeping room, outside of the sleeping areas, and on each floor of the house including the basement.
Buy, did you know that there are two common types of smoke alarms available to the general public? That’s right, you can choose between Ionization and Photoelectric smoke detection. Please don’t get scared by these big technical words; I will try not to get overly geeky when explaining the very important differences in these technologies.
Each of these types of alarms works best on different types of smoke. Ionization alarms react quickly to smoke from flaming fires, whereas it may never activate when smoke is present from smoldering fires. Photoelectric alarms react very quickly to the smoke from a smoldering fire whereas it may take 2 to 3 times longer than an ionization alarm during a flaming fire.
What do I mean by “different types of smoke?” Sure smoke can have different types of gasses and toxic substances, but it can also have different temperatures thus causing different particle sizes. It is the particle size that is relevant to the smoke detectors.
Let’s think of it in terms of water. What is the difference between water coming out of the tap and water coming from the shower? Temperature. It is all still water, but the particles of shower stream are much smaller than the particles of water at room temperature. Smoke acts the same way. The hotter the smoke, the smaller the particles.
“Hot” smoke particles coming from flaming fires are usually 0.01 – 3 microns in size while the “cold” smoke particles coming from smoldering fires are usually 0.3 – 10 microns. The take-away fact here is that ionization detectors do not react quickly to the larger “cold” smoke particles, and photoelectric detectors do not react quickly to the smaller “hot” smoke particles.
During flaming fires, seconds count when it comes to making it out safely, and photoelectric alarms may not provide you with sufficient notification in these cases. Smoldering fires may take up to an hour before the atmosphere is deadly, and ionization detectors have been known to remain inactivate even under the heaviest of “cold” smoke.
With that said, Chaffee Fire advocates the use of both technologies in the home. If you do not know which type of alarm you have, it should be written on the back label, “P” for photoelectric and “I” for ionization. Please, evaluate the level of safety for you and your family, and make the changes you feel are needed.
