Choosing a Smoke Detector

Here at Prep-Blog, we promote prudent and reasonable preparations for a wide range of possible situations, from ordinary home emergencies to moderate or severe widespread disasters. This prepping post is on the subject of choosing smoke detectors (and my next post will be on fire extinguishers) for your home or office.

There are two ways that smoke detectors detect a fire — that is their main goal, detecting fire, not necessarily smoke. One method uses an ionization sensor; the other uses a photoelectric sensor. The ionization sensor contains a small amount of americium (a radioactive element) which ionizes the air between two metal plates, allowing a small amount of current to flow. When smoke intervenes with the air between the plates, the current is disrupted, and the alarm is triggered. (EPA explanation)

The photoelectric sensor is equally clever. An LED sends light straight down a tube. Another tube connected at 90-degrees contains the light sensor. When smoke enters the straight tube, light from the LED is deflected to the sensor, setting off the alarm.

Each type of sensor works a little better on one type of fire versus another. The photoelectric sensor works best on smoky fires. The ionization sensor works best on fires that have less smoke, because the fumes still react in the sensor, decreasing ionization of the air. Which is better? The U.S. Fire Administration has this to say:

“There are many different brands of smoke alarms available on the market, but they fall under two basic types: ionization and photoelectric. It cannot be stated definitively that one is better than the other in every fire situation that could arise in a residence. Because both ionization and photoelectric smoke alarms are better at detecting distinctly different, yet potentially fatal fires, and because no one can predict what type of fire might start in a home, the USFA recommends that every residence and place where people sleep be equipped with:
Both ionization AND photoelectric smoke alarms, OR
dual sensor smoke alarms, which contain both ionization and photoelectric smoke sensors” (U.S. Fire Administration)

So you might want to get one of each, or spring for a slightly more expensive dual-sensor model.

How will the smoke alarm be powered? Your options are battery or wired. My thinking as a prepper is that power outages can last for days (or weeks), and so I would want an alarm that does not lose power with the electrical grid. Apartments and offices often prefer wired smoke alarms, because they don’t have to worry about batteries being removed or needing replacement. For the home or small office, I think you are better off with batteries.

Some smoke alarms contain a sealed lithium battery, designed to work for 10-years. After 10 years, you are supposed to replace any smoke detector, so you would buy a new one instead of a new battery. From my point of view, that situation is not optimal. What if you are near the end of the lifespan of the battery/detector, and some disaster makes it difficult to obtain a new one? Also, with the replaceable battery, you can always remove the battery if the detector goes off and the little button that is supposed to shut of the alarm fails to work right.

After doing some reading on the subject, and comparing prices and models, I opted for this smoke detector:
First Alert SA320CN Double Sensor Battery-Powered Smoke and Fire Alarm
There are other brands and models that are similar, so I’m not saying this is the best one. But it meets all of my criteria:
* dual sensor
* battery operated
* moderate price

– Thoreau

One Response to Choosing a Smoke Detector

  1. Very timely, one of our smoke alarms (of course theone on the vaulted ceiling) started chirping telling us it needed a new battery. After replacing the battery not once but 2 times the chirping wouldn’t stop. So now a whole new detector seems to be needed. Thanks for the info!!!