The old adage that "better safe than sorry" rings particularly true when it comes to carbon monoxide (CO) detectors. The toxic gas, produced when fuel is burned incompletely, can build up to deadly concentrations in enclosed spaces without sufficient ventilation. It is odorless, colorless and tasteless, making it extremely difficult to detect without proper equipment. Any kind of fossil fuel—coal, wood, oil, propane, natural gas—can produce CO when it is emitted from heating and cooking appliances. Likewise, gasoline, chainsaws, and other power tools can also emit CO at dangerous levels if not properly vented.

A carbon monoxide sensor functions by utilizing electrochemical technology to sense the presence of the toxic gas in the air. When the gas passes through a gas-permeable compartment, it lowers the material's resistance to electric current to a degree that is specific to the concentration of CO in the sensor. This information is then transmitted to an alarm system to warn you that CO is present in the air.

Different types of sensors use a variety of materials for this purpose, with metal oxide semiconductors being the most common. The type of n-type MOS used can affect the sensor's performance by altering its sensitivity, response time, and recovery time. These properties can be modified through proper doping and temperature control.

Some devices draw inspiration from hemoglobin, a protein that carries oxygen to the body's cells. When exposed to CO, the substance hijacks hemoglobin's binding sites, causing it to change from its normal dark red color to a cherry red hue. Some carbon monoxide detectors mimic this effect by using gel that absorbs the poisonous gas and then changes color in the presence of the gas. A light sensor tracks the gel's color, and if it becomes too red, an alarm will sound.

Other types of CO sensors work on a different principle. When the gas passes through a sensor's chip, it interacts with the metal oxide material to lower its electrical resistance. When the conductive metal of the chip reaches a certain level of carbon monoxide, this resistance decreases to an alarming degree. These kinds of sensors are commonly used in MEMS (micro-electromechanical systems)-based carbon monoxide gas detection.

Regardless of the technology, any functioning device that meets NFPA standards will greatly reduce the risk of exposure to harmful CO levels. NFPA recommends placing detectors according to manufacturer specifications in each bedroom and central location of the home and ensuring that they are not blocked by any fuel-burning appliances, such as stoves, furnaces, fireplaces, and fire pits.

Ideally, the detectors should be placed 15 feet away from any such appliance to ensure that they will detect CO before it can cause harm. In a study, researchers infused CO into an airtight Plexiglas chamber and placed detectors at three different heights. The results showed that detectors located in the ceiling or middle of the room had a higher reading than those placed nearer to the ground. This may indicate that these devices are more effective when placed closer to the source of CO emissions, but it is best to follow the recommendations of your manufacturer for the most accurate results.

The poisonous, odorless gas carbon monoxide is a normal byproduct of burning fuels like oil and gas in your home or office furnaces and fireplaces. It is normally released into the atmosphere and dispersed by ventilation, but when a heater malfunctions or there is insufficient ventilation it can build up to dangerous levels. Inhaling this stealth killer can restrict oxygen flow to the brain and heart, leading to death or other serious illness. A CO detector can help prevent deaths by detecting unsafe levels of carbon monoxide and alerting you to the threat.

Understanding the Science Behind Carbon Monoxide Detectors

Most home and office carbon monoxide detectors use electrochemical sensors. These sensors have electrodes covered in a special solution, and when carbon monoxide enters the gas-permeable compartment, it changes the electrical current flowing through the sensor, causing the device to trigger an alarm. Some sensors also display the level of carbon monoxide on a screen, which can be helpful when choosing a detector for your home or office.

These sensors vary by type and price. Inexpensive detector strips called biomimetic detectors (named because they work the way our bodies react to CO) have a beige-colored, gritty, sand-like "blob" in the middle of the detector that is impregnated with palladium and molybdenum salts. When carbon monoxide enters the air it oxidizes these chemicals, and the blob becomes black. The sensor then sends a signal to the electronic alarm.

More expensive, electrochemical instant-detection sensors have electrodes covered with a conductive metal that is altered when it comes into contact with carbon monoxide. This change in resistance causes the sensor to send a signal to the alarm, which can be as simple as an audible sound or as complex as a digital readout of the carbon monoxide level.

Another type of sensor uses circuitry applied to a silica chip. When the chip is exposed to carbon monoxide, it lowers the material's electrical resistance. The circuitry in the chip then detects this change and sets off an alarm. Some manufacturers offer detectors with both a display of the current carbon monoxide reading and a memory peak that shows the highest recorded reading over time.

While carbon monoxide is a dangerous gas at any concentration, it can be especially deadly at high concentrations, or at long-term exposure to low levels. For this reason, the National Fire Protection Association recommends installing a CO detector in every room of your home or business.

In addition to purchasing a CO detector, it is important to properly maintain your heating system and chimney. Having your gas furnace and chimney serviced annually can reduce the risk of carbon monoxide poisoning. You should also ensure there is adequate ventilation in your home, and that any leaking ducts are sealed properly. This can improve energy efficiency and reduce your carbon footprint. The old adage, "better safe than sorry," applies especially when it comes to safety and your family's well-being. If you have any questions about the proper care and maintenance of your carbon monoxide detector, feel free to contact us.