A
carbon monoxide detector or
CO detector is a device that detects the presence of the
carbon monoxideCarbon monoxide is a colorless, odorless and tasteless gas, yet very toxic to humans. It consists of one carbon atom and one oxygen atom, connected by a covalent double bond and a dative covalent bond...
(CO) gas in order to prevent
carbon monoxide poisoningCarbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and non-irritating, it is very difficult for people to detect...
. 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. Elevated levels of CO can be dangerous to humans depending on the amount present and length of exposure. Smaller concentrations can be harmful over longer periods of time while increasing concentrations require diminishing exposure times to be harmful.
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.
While CO detectors do not serve as
smoke detectorA smoke detector is a device that detects smoke. Commercial, industrial, and mass residential devices issue a signal to a fire alarm system, while household detectors, known as smoke alarms, generally issue a local audible and/or visual alarm from the detector itself.Smoke detectors are typically...
s and vice versa, dual smoke/CO detectors are also sold. Smoke detectors detect the smoke generated by flaming or smoldering fires, whereas CO detectors go into alarm and warn people about dangerous CO buildup caused, for example, by a malfunctioning fuel-burning device. In the home, some common sources of CO include open flames, space heaters, water heaters, blocked chimneys or running a car inside a garage.
Installation
The devices, which retail for $20-$60USD and are widely available, can either be battery-operated or AC powered (with or without a battery backup). Battery lifetimes have been increasing as the technology has developed and certain battery powered devices now advertise a battery lifetime of over 6 years. All CO detectors have "test" buttons like smoke detectors.
CO detectors can be placed near the ceiling or near the floor because CO is very close to the same density as air.
Since CO is colorless, tasteless and odorless (unlike smoke from a fire), detection in a home environment is impossible without such a warning device. It is a highly toxic inhalent and attracts to the hemoglobin(in the blood stream) 200x faster than oxygen, producing inadequate amounts of oxygen traveling through the body. In North America, some state, provincial and municipal governments have statutes requiring installation of CO detectors in construction - among them, the
U.S.The United States of America is a federal constitutional republic comprising fifty states and a federal district...
states of
AlaskaAlaska is the largest state of the United States of America by area; it is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
,
ConnecticutConnecticut is a state in the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and New York to the west and south ....
,
FloridaFlorida is a state located in the southeastern region of the United States, bordering Alabama to the northwest and Georgia to the north. It was the 27th state admitted to the United States...
,
GeorgiaGeorgia is a state in the United States. One of the original Thirteen Colonies that revolted against British rule in the American Revolution, it had been the last of the Thirteen Colonies to be established, in 1733. Georgia was the fourth state to ratify the United States Constitution, on January...
,
IllinoisIllinois , the 21st state admitted to the United States of America, is the most populous and demographically diverse Midwestern state and the fifth most populous state in the nation...
,
MarylandMaryland is a state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia and the District of Columbia to the south and west, Pennsylvania to the north, and Delaware to the east. It is comparable in size to the European country of Belgium. According to the U.S...
,
MassachusettsThe Commonwealth of Massachusetts is a state in the New England region of the northeastern United States. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. Most of its population of...
,
MinnesotaMinnesota is a state in the Midwestern region of the United States. The twelfth largest state by area in the U.S., it is the twenty-first most populous, with 5.2 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the...
,
New JerseyNew Jersey is a state in the Mid-Atlantic region of the United States. It is bordered on the north by New York, and to the east by the Hudson River, Upper New York Bay, the Kill Van Kull, Newark Bay, the Arthur Kill, Raritan Bay, Sandy Hook Bay, Westchester County, New York City, Long Island, and...
,
New YorkNew York is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous. The state is bordered by New Jersey and Pennsylvania to the south, and Connecticut, Massachusetts and Vermont to the east...
,
Rhode IslandRhode Island and Providence Plantations, more commonly referred to as Rhode Island , is a state in the New England region of the United States. It is the smallest U.S. state by area...
,
TexasTexas is the second-largest U.S. state in both area and population, and the largest state in the contiguous United States.The name had wide usage among native Americans, meaning "friends" or "allies"...
,
VermontThe State of Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd by land area, , and 45th by total area. It has a population of 621,270, making it the second least-populated state...
,
VirginiaThe Commonwealth of Virginia is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" because it is the birthplace of eight U.S. presidents. The geography and climate of the state are shaped by the Blue...
,
WisconsinWisconsin is one of the fifty U.S. states. Located in the north-central United States, Wisconsin is considered part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the...
and
West VirginiaWest Virginia is a state in the Appalachian and Mid-Atlantic regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, and Pennsylvania and Maryland to the northeast...
, the
CanadianCanada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean...
province of Ontario, and
New York CityNew York is the most populous city in the United States, and the center of the New York metropolitan area, which is among the most populous urban areas in the world. A leading global city, New York exerts a powerful influence over worldwide commerce, finance, culture, fashion and entertainment...
.
When carbon monoxide detectors were introduced into the market, they had a limited lifespan of 2 years. However technology developments have increased this and many now advertise up to 7 years. Newer models are designed to signal a need to be replaced after that timespan although there are many instances of detectors operating far beyond this point.
According to the 2005 edition of the carbon monoxide guidelines, NFPA 720 , published by the
National Fire Protection AssociationThe National Fire Protection Association is a U.S. organization charged with creating and maintaining minimum standards and requirements for fire prevention and suppression activities, training, and equipment, as well as other life-safety codes and standards...
, sections 5.1.1.1 and 5.1.1.2, all CO detectors “shall be centrally located outside of each separate sleeping area in the immediate vicinity of the bedrooms,” and each detector “shall be located on the wall, ceiling or other location as specified in the installation instructions that accompany the unit.”
Installation locations vary by manufacturer. Manufacturers’ recommendations differ to a certain degree based on research conducted with each one’s specific detector. Therefore, make sure to read the provided installation manual for each detector before installing.
CO detectors are available as stand-alone models or system-connected, monitored devices. System-connected detectors, which can be wired to either a security or fire panel, are monitored by a central station. In case the residence is empty, the residents are sleeping or occupants are already suffering from the effects of CO, the central station can be alerted to the high concentrations of CO gas and can send the proper authorities to investigate.
Sensors
Early designs were basically a white pad which would fade to a brownish or blackish colour if carbon monoxide were present. Such chemical detectors are cheap and 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.
Opto-Chemical
The detector consists of a pad of a coloured chemical which changes colour upon reaction with carbon monoxide. They only provide a qualitative warning of the gas however.
Biomimetic
A biomimetic (chem-optical or gel cell) sensor works with a form of synthetic
hemoglobinHemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
which darkens in the presence of CO, and lightens without it. This can either be seen directly or connected to a light sensor and alarm. Battery lifespan usually lasts 2-3 years. Device lasts on the average of about 10 years.
Electrochemical
This is a type of
fuel cellA fuel cell is an electrochemical cell that produces electricity from a replenishable fuel tank. The electricity is generated through the reaction, triggered in the presence of an electrolyte, between the fuel and an oxidant . The reactants flow into the cell, and the reaction products flow out of...
that instead of being designed to produce power, is designed to produce a current that is precisely related to the amount of the target gas (in this case carbon monoxide) in the atmosphere. Measurement of the current gives a measure of the concentration of carbon monoxide in the atmosphere. Essentially the electrochemical cell consists of a container, 2 electrodes, connection wires and an electrolyte - typically sulphuric acid. Carbon monoxide is oxidised at one electrode to carbon dioxide whilst oxygen is consumed at the other electrode. For carbon monoxide detection, the electrochemical cell has advantages over other technologies in that it has a highly accurate and linear output to carbon monoxide concentration, requires minimal power as it is operated at room temperature, and has a long lifetime (typically commercial available cells now have lifetimes of 5 years or greater). Until recently, the cost of these cells and concerns about their long term reliability had limited uptake of this technology in the marketplace, although these concerns are now largely overcome.
Semiconductor
Thin wires of the
semiconductorA semiconductor is a material that has an electrical resistivity between that of a conductor and an insulator, that is, generally in the range 10
3 Siemens/cm to 10
−8 S/cm. Devices made from semiconductor materials are the foundation of modern electronics, including radio,...
tin dioxideTin dioxide is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin. With many other names , this oxide of tin is the most important raw material in tin chemistry...
on an insulating ceramic base provide a sensor monitored by an integrated circuit. This sensing element needs to be heated to approximately 400 deg C in order to operate. Oxygen increases resistance of the tin dioxide, but carbon monoxide reduces resistance therefore by measurement of the resistance of the sensing element means a monitor can be made to trigger an alarm. The power demands of this sensor means that these devices can only be mains powered although a pulsed sensor is now available that has a limited lifetime (months) as a battery powered detector.
Device usually lasts on the average of 5-10 years.
Digital
Although all home detectors use an audible alarm signal as the primary indicator, some versions also offer a digital readout of the CO concentration, in parts per million. Typically, they can display both the current reading and a peak reading from memory of the highest level measured over a period of time. These advanced models cost somewhat more but are otherwise similar to the basic models.
The digital models offer the advantage of being able to observe levels that are below the alarm threshold, learn about levels that may have occurred during an absence, and assess the degree of hazard if the alarm sounds. They may also aid emergency responders in evaluating the level of past or ongoing exposure or danger.
Wireless
Wireless home safety solutions are available that link carbon monoxide detectors to vibrating pillow pads, strobes or a remote warning handset. This allows those with impediments such as hard of hearing, partially sighted, heavy sleepers or the infirm the precious minutes to wake up and get out in the event of carbon monoxide in their property.
Legislation
House builders in
ColoradoColorado is a U.S. state located in the Rocky Mountain region of the United States of America. It may also be considered to be part of the Western and Southwestern regions of the United States. Colorado entered statehood in 1876 and was nicknamed the “Centennial State”...
will be required to install carbon monoxide detectors in new homes in a bill signed into law in March 2009 by the state legislature.
House Bill 1091 requires installation of the detectors in new and resold homes near bedrooms as well as rented apartments and homes. It takes effect from July 1, 2009.
The legislation was introduced after the death of Denver investment banker Parker Lofgren and his family. Lofgren, 39; his wife Caroline, 42; and their children, Owen, 10, and Sophie, 8, were found dead in a multimillion-dollar home near Aspen, colorado on Nov. 27, 2008, victims of carbon-monoxide poisoning.
Manufacturers
- System Sensor
System Sensor is a St. Charles, IL company that specializes in fire protection products. System Sensor is part of Honeywell Life Safety Group.-History:...
- DuPont
E. I. du Pont de Nemours and Company , commonly referred to as DuPont or Du Pont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Eleuthère Irénée du Pont. DuPont is currently the world's second largest chemical company in terms of market capitalization and...
- First Alert
First Alert is an American safety brand. They make carbon monoxide detectors, smoke alarms, fire extinguishers, and other safety products like flashlights and fire escape ladders...
- Kidde
Kidde is a business that manufactures and distributes fire detection and extinguishing equipment.-History:The company was founded by Walter Kidde in 1917 in the United States...
- KWJ Engineering, Inc.
- Sprue Aegis
- Duomo (UK) Ltd.
- Ei Electronics (Ireland) www.eielectronics.com
External links