How to Compare a CO Detector & a Smoke Detector

Keep the battery charged in all smoke and CO detectors.

Smoke detectors and carbon monoxide detectors are two of the most essential devices for home safety. While they look similar on the outside, their functions are entirely different.

How Smoke Detectors Work

There are two types of smoke detectors. Photoelectric detectors, the older of the two, are triggered when smoke interferes with a beam of light that completes an electrical circuit. Ionization detectors, the more sensitive type, have a slightly radioactive metal plate that emits alpha particles which collide with air particles. This collision produces a charge, and the charge produces a current. The alarm is triggered when smoke particles latch on to the air particles, eliminating the charge and disrupting the current produced.

How Carbon Monoxide Detectors Work

There are three types of carbon monoxide alarms: metal oxide semiconductor (MOS), biomimetic and electrochemical. Electrochemical detectors work like ionization smoke detectors, whereby an electrical current is produced in the presence of carbon monoxide. Biomimetic detectors are discs covered in a special gel that changes color near elevated levels of carbon monoxide, and MOS detectors use heated tin oxide that reacts with carbon monoxide.

Combination Detectors

Since both smoke and carbon monoxide are dangerous, many companies sell alarms that detect both substances. Available in both battery-operated and wire-in styles, they reduce installation time and ensure that power will not run out in one detector before the other.

References

• Environmental Protection Agency: How Smoke Detectors Work
• Detectors and Alarms: Carbon Monoxide Detectors and Smoke Alarm Combination Alarms
• Canada Mortgage and Housing Corporation: Carbon Monoxide