How Do Carbon Monoxide Detectors Work?

What Is Carbon Monoxide?

Every year, at least 430 people die in the U.S. from accidental CO poisoning. Approximately 50,000 people in the U.S. visit the emergency department each year due to accidental CO poisoning. Red blood cells pick up CO quicker than they pick up oxygen. When you inhale CO, your body replaces the oxygen in blood with CO. People who are sleeping or who have been drinking alcohol can die from CO poisoning before ever having symptoms.

Carbon monoxide is a colorless, odorless, and tasteless gas that can cause serious health problems or even death if inhaled. Carbon monoxide is produced by incomplete combustion of fuels such as gas, oil, coal, wood, charcoal, kerosene, propane, and others. Carbon monoxide can leak from faulty appliances, fireplaces, furnaces, water heaters, generators, cars, grills, and other sources.

As humans, our basic senses have evolved to protect us from various threats, but some threats are too subtle for our bodies to detect. Carbon monoxide is one such threat. It is a colorless, odorless, and poisonous gas that is produced when materials like coal, oil, and gas are burned incompletely in engines or heating systems.

When fuels burn properly, they produce water, energy, and carbon dioxide (CO2). However, if there isn’t enough oxygen available for the fuel to burn completely, carbon monoxide is produced instead of carbon dioxide. This is where the danger lies. Carbon monoxide is produced in a variety of situations, such as when gas central heating boilers don’t receive enough oxygen from the room, or when engines, furnaces, forges, or any other equipment that uses oxygen to produce energy through combustion are used.

Carbon monoxide is harmful because it readily attaches to the protein in red blood cells, called hemoglobin, which carries oxygen around the body. Carbon monoxide is over 200 times better at attaching to oxygen than oxygen itself. When a person breathes in carbon monoxide, it attaches to the hemoglobin, stopping it from carrying oxygen to the brain and the rest of the body. This can cause drowsiness, followed by unconsciousness and death.

Fortunately, there are carbon monoxide detectors that can alert you to the presence of this gas.

What Are Carbon Monoxide Detectors?

Carbon monoxide detectors are devices that sense the presence of carbon monoxide in the air and sound an alarm when the level reaches a dangerous threshold. Carbon monoxide detectors can save lives by alerting you to evacuate your home before you are overcome by carbon monoxide.

It’s important to follow the manufacturer’s instructions for installation, use, and maintenance of carbon monoxide detectors, and to replace them according to the recommended timeline or expiration date. The average lifespan of a carbon monoxide detector is about 7 years, and it’s recommended to replace them every 5 years.

Most carbon monoxide detectors have an end-of-life indicator that tells you when they need to be replaced. This indicator may be a light, a sound, or a message on the display that shows “replace” or “end” or something similar. Some detectors may also beep every 30 seconds or so when they reach their end-of-life.

You should check your detector’s manual for more details on how to identify its end-of-life indicator and what it means. You should also test your detector monthly by pressing its test button and making sure it sounds an alarm.

When replacing your old detector, turn off any sources of combustion such as appliances, fireplaces, furnaces, water heaters, generators, cars, grills, etc. Then remove the old detector from its mount on the wall or ceiling and dispose of it properly according to local regulations. Install the new detector following its instructions carefully, and test it by pressing its test button and making sure it sounds an alarm. Finally, turn on any sources of combustion again.

Carbon monoxide detectors are essential safety devices that can save lives. However, they do have a limited lifespan and can degrade over time due to exposure to environmental factors. To ensure the effectiveness of your carbon monoxide detector, it’s important to follow the manufacturer’s instructions and to replace the detector according to the recommended timeline or expiration date.

Moreover, it’s important to take proper precautions to prevent carbon monoxide exposure in the first place. Some measures you can take include:

- Having your heating system, water heater, and any other gas, oil, or coal-burning appliances serviced by a qualified technician annually to ensure they are working correctly.
- Ensuring that all gas appliances are properly ventilated to the outside and have an adequate supply of fresh air.
- Never using a gas oven or range to heat your home.
- Never leaving a car running in a closed garage or in any enclosed space.
- Installing a carbon monoxide detector on every level of your home and near sleeping areas.
  Testing your carbon monoxide detector monthly and replacing it according to the manufacturer’s guidelines.
- By taking these steps, you can help protect yourself and your family from the dangers of carbon monoxide. Remember, prevention is always the best defense against carbon monoxide poisoning. Stay safe and stay informed.

How Do Carbon Monoxide Detectors work?

Carbon monoxide detectors come in two basic kinds: inexpensive detector strips and electronic alarms. Inexpensive detector strips are sometimes called biomimetic detectors because they mimic the way our bodies respond to carbon monoxide. These detectors are pieces of plastic with a small beige-colored “blob” in the middle. If there’s a high level of carbon monoxide in the room, the blob changes color from beige to black. The blob is gritty and sand-like and impregnated with a catalyst made from chemicals such as palladium and molybdenum salts. When carbon monoxide touches the detector, it’s oxidized by the chemical salts on the strip and turns into carbon dioxide. The chemicals on the strip are simultaneously reduced and change color to black. Once the carbon monoxide is removed, a transition-metal salt on the blob steals some oxygen from the air and changes the catalyst back to its original chemical form. In other words, the catalyst regenerates itself in the air.

Although inexpensive detector strips are a good way to give yourself basic protection if you can’t afford anything more sophisticated, they have some disadvantages. First, these detectors don’t sound an alarm, so you have to keep looking at them to notice that the color has changed. Another problem is that strip detectors have to be replaced every 3–6 months, which means that, after a few years, you’ve spent almost as much as if you’d bought an electronic alarm in the first place.

Electronic carbon monoxide alarms, on the other hand, are more sophisticated. They work in a variety of different ways, such as colorimetric detectors, metal-oxide detectors, and electrolytic detectors. Colorimetric detectors have a chemical blob inside that changes color when carbon monoxide is present. A light beam shines onto the blob, and an “electronic eye” measures the light reflected back. If there’s no carbon monoxide around, the strip is beige, and lots of light is reflected. With carbon monoxide present, the strip turns black, the light shining onto it is absorbed, and little or none is reflected back. The electronic eye detects the lack of reflected light and sounds a shrill, piercing alarm to alert the occupants of the presence of carbon monoxide. On the other hand, metal-oxide detectors have open chambers containing sensors made of metal oxide, such as tin or platinum. When carbon monoxide is present, the metal oxide reacts with it, causing the carbon monoxide to convert into carbon dioxide and producing heat at the same time. An electronic circuit then monitors the temperature inside the chamber and sounds an alarm if too much heat is produced too quickly. In some detectors, the circuit measures the resistance of the sensor element and infers the presence of carbon monoxide from that.

These types of detectors are often battery-operated and can be powered by your main electricity outlet. Some detectors, like electrolytic detectors, work similarly to a battery, with terminals called electrodes made from platinum metal dipped into a chemical solution called an electrolyte. When carbon monoxide is present, the electrolyte conducts electricity more readily, triggering an alarm. Although electrolytic detectors are usually the most sensitive and accurate, they are also the most expensive and need to be powered from an electricity outlet instead of batteries, making them less suitable for places without outlets nearby.

Electronic detectors can vary in sophistication, with some being simple “on” or “off” types that trigger an alarm when carbon monoxide is present in dangerous levels. More advanced detectors have digital displays that show the amount of carbon monoxide present as a reading in parts per million (PPM). These detectors can alert you to a gradually worsening problem with carbon monoxide by showing a progressively increasing PPM reading. Any reading over 35 PPM (the maximum exposure level permitted in workplaces for any eight-hour period by the National Institute for Occupational Safety and Health, NIOSH) is a cause for concern, and it’s recommended to check your appliances or room ventilation if you get any significant PPM reading at all.

Regarding carbon monoxide detectors, it’s essential to have enough detectors in the building. You need one detector near each appliance, fire, furnace, fuel-burning engine, or other device that could potentially produce CO gas if it malfunctions. For example, if you have a gas boiler in one room of your house and separate, standalone gas fires (or coal fires) in other rooms, more than about 10 meters (30 feet) away from your detector or on other floors of the same building, you need one detector next to each of them.

It’s also important to note that carbon monoxide detectors need to be installed correctly to be effective. They should be installed at least five feet from the ground, away from windows, and near sleeping areas. Make sure to follow the manufacturer’s instructions when installing and testing your carbon monoxide detectors. Additionally, it’s recommended to test your detectors regularly to ensure they are working correctly.

Carbon monoxide is a dangerous gas that is difficult to detect with our basic senses. Carbon monoxide detectors are essential for keeping you and your family safe from this invisible gas. They come in different types, including inexpensive detector strips and electronic alarms, and work in a variety of ways, such as chemical “blob” detectors, colorimetric detectors, metal-oxide detectors, and electrolytic detectors. No matter the type, it’s important to have enough detectors in your home and to install and test them correctly to ensure they are working properly. By doing so, you can rest assured that you and your family are protected from the dangers of carbon monoxide poisoning.

The type of carbon monoxide detector features in the following video is a TGS5042, which is a low-cost electrochemical sensor:

The TGS5042 is a low-cost electrochemical carbon monoxide sensor that is part of the TGS5000 series. Its most notable feature is its excellent stability due to Figaro’s patented electrolyte, which is a low concentration solution of KOH, KHCO3, and K2CO3. This sensor also has an extended sensor life of 10 years and a cost-effective structure with two electrodes. The TGS5000 series has achieved this cost-effectiveness by producing more than ten million sensors per year and reducing production costs. The TGS5042 sensor has additional features that simplify sensor handling and reduce overall costs for end-users, such as direct soldering, wave soldering, individual sensitivity data printed on the sensor body, and UL recognition.

Do Carbon Monoxide Detectors Degrade Over Time?

Carbon monoxide detectors can degrade over time. Most carbon monoxide detectors have a limited lifespan of about 5 to 10 years. After that, they may no longer be reliable in detecting carbon monoxide.

One of the primary reasons that carbon monoxide detectors degrade over time is due to the sensor inside them. Carbon monoxide detectors use an electrochemical sensor, which contains a gel-like electrolyte that reacts with carbon monoxide to produce an electrical current. Exposure to air, temperature changes, and other environmental factors can cause the electrolyte to dry out and lose its ability to produce a reliable electrical current.

Some types of sensors used in carbon monoxide detectors can also be affected by environmental factors such as humidity and pollutants. Exposure to these factors can cause the sensor to become less sensitive or to generate false readings.

Some carbon monoxide detectors contain other components, such as microprocessors or batteries, that can degrade over time due to exposure to environmental factors. This can also cause the detector to become less reliable in detecting carbon monoxide.

Also, some carbon monoxide detectors are intentionally designed by manufacturers to beep to alert owners to replace the detector within a predetermined time range.

If you have stored carbon monoxide detectors for an extended period of time, it’s recommended to check the manufacturer’s guidelines to see if they have an expiration date or recommended replacement timeline. It’s also recommended to test the detectors before use to ensure they are functioning properly.

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