Last week we looked at fire safety tips we can implement as we prepare for the holiday season. One of the best ways to prevent injury or death as a result of a fire is proper use of a smoke detector. This suggestion begs the question, is an inexpensive detector just as good as a top of the line model, or are there features being lost on the cheaper model?

My investigation led me to the internet, and to a variety of informational sources. Here is a summary of what I learned and where I learned it, in case you want to read more about the subject.

Perhaps the most remarkable thing about smoke detectors is that they are widely available for less than ten dollars, and that they may very well save your life.

It turns out that the least expensive models, sometimes available for as little as five dollars per detector, do an adequate job of detecting hot, blazing fires. They are reliable and dependable, and in that situation, they can save your life.

But as you look further into the world of fire safety, it becomes apparent that there are several types of fire in the home that can harm you, and not all detector types are equally successful at providing advance notice of that fire.

First, let’s look at the basic units. These contain a sensor that detects smoke using ionization.

In a nutshell, a small amount of radioactive material is placed in a chamber. Particles from that material generate a small, but measurable, current between two plates in the detection chamber. When smoke enters the ionization chamber, it disrupts the current. The smoke detector measures the drop in current and triggers the alarm.

Ionization sensor models are good at detecting high-flame fires, but are less effective at sensing smoky fires, such as smoldering bedding. In addition, ionization type units are prone to false alarms. Routine kitchen or bath activities may cause the alarm to sound. So can spraying nearby windows with common window cleaner solutions.

The second type of smoke detector commonly used today is the photoelectric detector.

The concept here is similar to a chime sounding when you enter store with an electric eye. When you disrupt the beam of light, a bell sounds. Likewise, in a photoelectric sensor, as smoke enters the detection chamber, it scatters light from a beam, and a sensor detects the disruption. The detector then sets off the alarm.

Photoelectric detectors excel at sensing furniture fires, which tend to produce lots of smoke, but few actual flames. That’s why this type of detector is most often recommended for sleeping areas.

I learned a lot about the inner workings of smoke detectors at www.howstuffworks.com and would recommend you visit the site for more details.

Both types, ionization and photoelectric, are effective as smoke detectors. And both types must pass the same rigid tests before they can be certified as UL smoke detectors by Underwriters Laboratories. And in both types of detectors, steam or high humidity can cause condensation on the electronic circuit boards which may cause the alarm to go off accidentally.

As a matter practical usage, no smoke detector can work if it is not powered. So units that are hard-wired to your electrical system are probably most safe. However, the battery powered units are less expensive and much easier for the home owner to install. In addition, they are equally effective, provided the batteries are replaced when needed.

Another fact I learned is this: the ionization units have a built-in fail-safe against run down batteries. When the battery begins to fail in an ionization detector, the ion current level falls, and the alarm is automatically triggered. This provides a warning that the batteries need replacing before the detector fails altogether.

More than three of four detectors in American homes are ionization detectors. That’s because they are much less expensive to produce, and therefore sell for much less. Consumer studies I saw on the internet recommended detectors which combined both the ionization and the photoelectric methods for maximum protection. Unfortunately, the least expensive combination units I could find cost just over thirty dollars.

Another interesting statistic is this: in 1994, the Consumer Product Safety Commission found that one in four homes equipped with a smoke detector had a non-operating unit in the house. Investigators stated that the primary reasons for the defective units were dead or missing batteries, dust or grease clogging the detector’s vents, and infestation of the sensing chamber by insects.

I guess the bottom line is that any smoke detector is better than none at all, and that we have a responsibility to ourselves and our families to keep the detectors powered and clean. And a last piece of advice is this: test your units on a weekly basis to make sure they are in good working order.

For more detailed information about home fire prevention, visit www.about.com and enter "smoke detectors."