Carbon monoxide detector

Not to be confused with carbon monoxide alarm.

A carbon monoxide detector is a device that detects carbon monoxide (CO). Although CO detectors are often used as initiating devices on fire alarm systems, they are typically programmed to generate a supervisory signal or special CO alarm signal instead of a standard alarm signal, so that their outputs can be distinguished from fire evacuation signals.

Operation

Conventional CO detectors take external 24 volt power to operate, and short a special IDC when activated. Intelligent CO detection is starting to become more and more common, though it is still very common in older applications to see the CO detectors that are tied to monitor modules.

Required locations

NFPA 72 section 17.12.1 requires CO detectors in all rooms with permanent fuel-burning appliances, on every habitable level and every HVAC zone of the building, and outside every sleeping room within 21 feet of travel distance. Section 17.12.9 also requires system designers to consider the effect of an HVAC system on the spread of CO and integrate CO detectors with HVAC shutdown and/or smoke control if needed. Additionally, section 29.7 allows carbon monoxide detectors to be used in place of carbon monoxide alarms in dwelling units.

NFPA 101 includes several occupancies that require CO detection:

• Section 12.3.4.4 requires CO detection in new assembly occupancies in rooms with permanent fuel-burning appliances/fireplaces and in occupiable spaces served by the first supply air register of a fuel-burning HVAC system, as well as all occupiable spaces adjacent to garages that are not sufficiently ventilated.
• Section 14.3.4.4 requires CO detection in new educational occupancies in rooms with permanent fuel-burning appliances/fireplaces and in occupiable spaces served by the first supply air register of a fuel-burning HVAC system, as well as all occupiable spaces adjacent to garages that are not sufficiently ventilated or separated from the space.
• Sections 18.5.2.3 and 19.5.2.3 require health care occupancies to have CO detection in rooms with fireplaces.
• Section 24.3.4.2 allows CO detectors to be used in place of CO alarms in one- and two-family dwellings.
• Section 26.3.4.6 allows CO detectors to be used in place of CO alarms in lodging and rooming houses.
• Sections 28.3.4.7.1 and 29.3.4.6.1 allow CO detectors to be used in place of CO alarms in hotels and dormitories, and sections 28.3.4.7.4 and 29.3.4.6.4 require CO detectors in non-guest rooms with permanent fuel-burning appliances/fireplaces and in occupiable spaces served by the first supply air register of a fuel-burning HVAC system, as well as spaces adjacent to communicating garages.
• Section 30.3.4.6.1 allows CO detectors to be used in place of CO alarms in new apartments, and section 30.3.4.6.4 requires CO detectors in non-dwelling areas with permanent fuel-burning appliances/fireplaces and in occupiable spaces served by the first supply air register of a fuel-burning HVAC system, as well as spaces adjacent to communicating garages.
• Section 32.2.3.4.4 allows CO detectors to be used in place of CO alarms in new small residential board and care occupancies.
• Section 32.3.3.4.9.2 requires CO detectors in new large residential board and care occupancies in rooms with fuel-burning appliances/fireplaces, in occupiable spaces served by the first supply air register of a fuel-burning HVAC system, in spaces adjacent to communicating garages that are not sufficiently ventilated, and on every level of an occupancy that is otherwise required to have CO detection. Section 32.3.3.4.9.4 allows CO detectors inside residential units to be substituted with CO alarms.

On the other hand, most of the requirements in IBC/IFC are not occupancy-specific. Section 915.1.1 requires CO detection in buildings with CO sources, buildings served by CO-producing furnaces, buildings with attached private garages, and buildings with CO-producing vehicles inside. Under section 915.2, these must be located directly outside sleeping rooms, inside sleeping rooms with CO sources, throughout Group E occupancies, in all spaces served by CO-producing furnaces (or only the first space served by the main duct, if signals are transmitted to an approved location), in rooms adjacent to communicating private garages that are not sufficiently ventilated, and in rooms with CO sources (unless environmental conditions prohibit this, in which case detection may be present in an approved adjacent room). Section 915.3 allows CO alarms to be used in dwelling units without fire alarm systems, but all other areas requiring CO detection must use CO detectors.