A carbon monoxide detector or CO detector is a device that detects the presence of the carbon monoxide (CO) gas in order to prevent carbon monoxide poisoning. CO is a colorless and odorless compound produced by incomplete combustion. It is often referred to as the "silent killer" because it is virtually undetectable without using detection technology.CO detectors are designed to measure CO levels over time and sound an alarm before dangerous levels of CO accumulate in an environment, giving people adequate warning to safely ventilate the area or evacuate. Some system-connected detectors also alert a monitoring service that can dispatch emergency services if necessary.
Are They Really Necessary?
If you take the actions above, you greatly reduce your risk of CO poisoning. But unanticipated dangerous incidents may still occur despite your best efforts to avoid CO. The installation of at least one CO detector in your home is a good safety precaution and in some municipalities, it is the law. A detector might be your second line of defence, but it is necessary. You should have one in your home today.
How Do CO Detectors Work?
There are three basic types of CO sensors — metal oxide, biomimetic and electrochemical. Note that while there may be performance differences between these technologies, all detectors are tested and approved for their operation. The retail cost of a detector will generally relate to the number of features included and its warranty conditions.
Metal-oxide-semi-conductor (MOS)
This is the original technology for detecting CO. Heated tin oxide reacts with CO to determine the levels of the toxic gas. There is no need to remember to check batteries as units must be connected to house power. Models that offer up to 20 hours of battery backup are available.
Biomimetic
Biomimetic detectors have gel-coated discs that darken in the presence of CO and the colour change sounds an alarm. This technology is less expensive and can be battery operated.
Electrochemical
In this type of detector, a chemical reaction with CO creates an electrical current that sets off an alarm. Electrochemical detectors are highly sensitive and offer accurate readings at all CO levels. Most units come with a continuous digital readout and a memory feature that allows you to check past CO levels. This technology offers a fast reset time. Most units sound an alert when the sensor needs to be replaced.
Sensors
Early designs were basically a white pad which would fade to a brownish or blackish color if carbon monoxide were present. Such chemical detectors were cheap and were widely available, but only give a visual warning of a problem. As carbon monoxide related deaths increased during the 1990s, audible alarms became standard.
The alarm points on carbon monoxide detectors are not a simple alarm level (as in smoke detectors) but are a concentration-time function. At lower concentrations (eg 100 parts per million) the detector will not sound an alarm for many tens of minutes. At 400 parts per million (PPM), the alarm will sound within a few minutes. This concentration-time function is intended to mimic the uptake of carbon monoxide in the body while also preventing false alarms due to relatively common sources of carbon monoxide such as cigarette smoke.
There are four types of sensors available and they vary in cost, accuracy and speed of response.The latter three types include sensor elements that typically last up to 10 years. At least one CO detector is available which includes a battery and sensor in a replaceable module. Most CO detectors do not have replaceable sensors.
