High Altitude Effects on an Ionization Smoke Detector

Ionization Smoke Detectors

• Ionization smoke detectors contain a tiny portion of radioactive material inside a metal compartment. This material, americium-241, lodges in the ionization chamber, consisting of two metal plates close together. One plate charges positively, the other negatively. In between the plates are alpha particles emitted from the radioactive material. These particles combine with the air in the chamber, producing charged particles. While the positive plate attracts electrons, or negatively charged ions, the negative plate attracts nitrogen and oxygen, or positively charged ions. The constant ion flow creates a regular current. If smoke enters the chamber, the current disrupts. Particles from the smoke attach to the ions, bringing them back to a neutral state, and less electricity flows between the two plates. The current drops to a particular point, triggering the alarm.

Disadvantages

• An ionization detector loses its sensitivity in high altitudes. The higher the elevation and thinner atmosphere, the greater the amount of natural radiation. This increase, along with air composition, affects the ionization smoke detector's accuracy, regularly triggering false alarms. With frequent false alarms, home or building occupants tend not to pay attention when the detector goes off. Ignoring a smoke detector due to frequent false alarms renders if virtually useless. Because of the radioactive material in the ionization smoke detector, it must be sent back to its manufacturer for proper disposal when no longer working or needed.

Other Considerations

• In addition to high altitude, ionization smoke detector's ability to detect the presence of smoke is affected if the installation area is very dirty or obstructed. Very high ceilings and certain types of ceilings, such as those with deep beams, may also hamper the ionization smoke detector's efficiency.

Photoelectric Smoke Detectors

• For the high altitude dweller, installing a photoelectric smoke detector is your safest choice. Photoelectric smoke detectors rely on an electric current producing a light beam. If the light beam interrupts, the alarm goes off. Since the ionization smoke detector more effectively detects smoldering fires and the photoelectric smoke detector does not as effectively detect flames, you may want to install both versions on your premises if you do not live in a high altitude area.