How a CO detector works

• Carbon monoxide is a gas that enters the red blood cells and cause permanent damage to brain, lungs and heart. The more it enters the body, the more damage it can cause.
• Not only this, but CO is odorless, colorless, tasteless and you can’t see it.
• Having a CO detector can reduce the risk of death.
• Long exposures with low amounts of CO is just as bad as high amounts of CO with short exposure to the gas. Therefore no matter how long you you might be exposed to the CO, we must always make sure to have one in cases of emergency.
• When a CO detector senses gas in the air, it sends out a signal to pulse the alarm. The more carbon monoxide it detects, the higher the pulse and signal will be. CO detectors also send color sensors that change colors when a high amount of CO is exposed in the air.
• Remember that a CO detector must NOT be placed within 15 feet of any appliance. This is because you don't want the CO detector to activated when there is only a small amount of CO in that part the air. I.e, no false alarms.
• There are two common types of CO detectors. One that is battery-powered, and one that it a plug in.
o The battery powered is the most common, as it can be placed in higher placed. Note: Carbon monoxide rises up to the ceiling when exposed to air.
o The plug in is also used, usually for people that are forgetful of changing batteries.
• CO detectors are recommended to be in every bedroom of the house like a fire alarm, but most families prefer to have one in every floor in the house. The placement of a CO detector is just as important. It is recommended for them to be placed near the bedrooms to hear the sound go off in case of an emergency.
• The usual lifespan of CO detectors are usually two years, so frequent checks on the device are necessary.

sources: 

http://home.howstuffworks.com/home-improvement/household-safety/tips/carbon-monoxide-detector.htm

http://chemistry.about.com/od/howthingswork/a/codetectors.htm

http://www.youtube.com/watch?v=Oj1XfqsXUFg&feature=g-hist