Why are photoelectric smoke alarms better than ionization detectors?

There’s no denying the fact that ionization smoke detectors and smoke alarms are a whole lot cheaper than their photoelectric counterparts. At the same time, it’s also a fact that money’s suddenly a non-issue when someone’s about to die in a raging house fire. The bottom line is “Do not skimp because of money as your life or that of a loved one may very well depend on it.”

The difference in performance between the two detectors is simply this: Where a ionization smoke alarm works best in a raging fire in a commercial environment where the smoke particulates (particles) are relatively small, the photoelectric smoke alarm works better in a residential setting where the smoke particles are relatively big. This kind of fire is usually found in a home where there are carpets, draperies, bed spreads, couches, chairs, tables, clothes, and other household items.

The difference between the two technologies is as different as night is to day. Photoelectric smoke alarms rely on a smoke chamber and the reflective properties of a large diameter smoke particle. A photoelectric emitter at one end of a narrow passage leads to a dead end. A passage that intersects the first at an angle contains a photo receptor capable of receiving light when the same is reflected from smoke particles that enter the chamber.

Because of the nature of the design, it takes a relatively large smoke particle to reflect enough light to the end of the photo receptor passage, thus triggering an alarm. When there’s no smoke, the light merely ends within the first passage where there is no photo receptor present. This result in no alarm (see drawing). The design of these detectors is deliberate because residential dwellings contain the kinds of combustibles that create such a large particulate of smoke. This is why the photoelectric smoke alarm is the best type of detector to use in this type of setting.

The following video provides information on residential smoke alarms. The individual in the video provides information on the differences between these two distinctly different smoke alarms. Check it out and continue reading when the video is done…

The other issue that you need to know about is that of fire code, which says, “Unless otherwise recommended by the manufacturer’s published instructions, single-and multiple-station smoke alarms installed in one- and two-family dwellings shall be replaced when they fail to respond to operability tests but shall not remain in service longer than 10 years from the date of manufacturer (Section of the NFPA 72®, 2013 edition, National Fire Alarm and Signaling Code, National Fire Protection Organization, Quincy, MA).
For additional information on this subject, read NFPA’s final word on the topic here: http://bit.ly/2znx52e.

Here’s a second video that goes into even more detail. Please scroll down when done to read the conclusion of this article:

If you’re unsure of the age of your smoke alarms, decide on the side of safety by replacing them now. For more information, send us a comment using the contact below, or call the office at 614-754-1393.