Fire & Intrusion

April 22, 2010
The code side of carbon monoxide sensing

My recent articles have explained how the 2010 edition of NFPA 72 the National Fire Alarm and Signaling Code(r) now includes many rules for other life safety functions including carbon monoxide detection. The latest (2009) edition of NFPA 720, Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment(r), has also been overhauled. The new format mirrors NFPA 72 as if a zero was added to the 72 and the term "smoke" replaced with "CO." The good news is, if you are already familiar with the rules of NFPA 72, 720 will be easy. The 720 overhaul has added commercial buildings to the household requirements and includes comprehensive new rules for detector locations and the testing requirements for CO systems. Chapter 9 of 720 covers single- and multiple-station CO alarms and detector systems for one- and two-family homes. However, this article will also address the rules for system-type detectors in Chapters 4 through 7, as well as Chapter 8. Chapter 8 covers all the testing requirements for both alarms and detectors.

As you may know, there's an issue regarding compliance with this standard using today's CO system equipment. The main issue stems from 720's requirements for all CO alarm signals to be heard/seen throughout the occupiable areas of the building. Notification is straightforward if multiple interconnected, AC/battery type, CO alarms with their built-in sounders are used, but this method can be expensive, impractical or impossible with large commercial/residential occupancies. While 720 also permits a building's fire alarm EVAC system to be used for notification, another alternative is to provide a system of CO detectors. CO detectors, like smoke detectors, must be connected to a control panel and, like a fire alarm system, the control panel would provide the building-wide alarm with separate appliances.

However, when preparing this article, I found that none of my industry sources were aware of a control panel that could produce the synchronized Temporal 4 sound required by NFPA 720 using listed notification appliances, or knew of any separate, self-contained Temporal 4 sounders being sold. However, there are other rules in NFPA 720 that, when combined, provide a solution to this notification/sounder dilemma. These rules state that if the CO alarm signals are transmitted either off-site to a monitoring company, or on-site to a constantly staffed location, then the alarm notification is only required to be provided in the area where CO was detected using the detector's built-in sounder. While all CO alarms have sounders, not all CO detectors have built-in sounders. Therefore, the CO detectors you select must contain a built-in temporal 4 sounder. So, using detectors with sounders, along with the 24/7 monitoring of alarm signals, an NFPA 720 compliant CO detector system is possible.
Greg Kessinger SET CFPS is SD&I's longtime resident fire expert and regular contributor to the magazine. Reach him at [email protected].