3) CO detectors are now held to the same life safety standard as smoke detectors: They will send trouble signals to the control panel and facilitate wiring supervision.
CO detector trouble signals are required to be indicated visually and audibly at the control panel and supervising station. Therefore, conventional hard-wired CO detectors must have an integral trouble relay that will send trouble conditions to the control panel such as a sensor failure or end-of-life signal.
NFPA 720-2009 requires manufacturers of system-connected CO detectors to incorporate the same critical life safety supervision concepts as smoke detection devices to prevent undetected device failures. In addition to the trouble signals noted previously, CO detectors must facilitate wiring supervision.
The connection between the initiating device circuit conductors and the CO detector are required to be monitored for integrity.
Requirements (see figure) are particularly important for installers when selecting a CO detector.
4) CO detector location is more specific than ever.
Unlike smoke detectors, the 2005 edition of NFPA 720 had limited requirements for the placement of CO detectors. The standard required CO detectors to be centrally located outside of each separate sleeping area in the immediate vicinity of the bedrooms, and it also referred to the manufacturer’s published instructions. Instructions differed between manufacturers, however, and this confused installers and Authorities Having Jurisdiction (AHJ). Some manufacturers call for detectors to be installed on the ceiling, while others call for wall installation.
Based on research conducted by the Fire Protection Research Foundation (FPRF), NFPA 720-2009 has specific requirements for the location of CO detectors in commercial buildings and dwelling units. In commercial buildings, CO detectors need to be located on the ceiling in the same room as permanently installed fuel-burning appliances and centrally located on every habitable level and in every HVAC zone of the building. In dwelling units, CO detectors must be installed outside each separate sleeping area and on every level of a dwelling unit, including basements. Applicable laws, codes and standards may require additional locations.
5) New secondary power supply requirements for CO detection systems differ considerably from fire alarm systems.
NFPA 720-2009 requires CO detection systems to have sufficient secondary power to operate the system under quiescent load (system operating in a normal condition) for at least 24 hours. After that time, the system must operate all of the CO notification appliances for 12 hours if a supervising station does not monitor the system. If the CO detection system is monitored by a supervising station, the 12-hour requirement can be reduced to 60 minutes.
Though a five-minute requirement is mandated for fire alarm systems, a 12-hour alarm requirement for CO systems is necessary for non-monitored systems because occupants could be away from the unit for several hours. If the CO alarm signal stopped sounding before occupants returned, the occupants would be unaware that there were dangerous levels of CO gas present.
Tags: Carbon monoxide, Guidelines
Posted in Carbon Monoxide Detection, Commercial, Fall 2008, Guidelines, NFPA
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