Detecting carbon monoxide
When building professionals discuss carbon monoxide, they're uncertain as to where and how detection should be installed.
When building professionals discuss carbon monoxide (CO), they're uncertain as to where and how detection should be installed. Building owners, their design teams, and the responsible code-enforcement authorities all want direction for detector locations that will protect occupants from accumulations of CO gas. Recently, some building and life-safety codes have begun to prescribe CO detection requirements to address these uncertainties. What is certain, however, is the insidious nature of the threat.
CO is an invisible, odorless killer responsible for approximately 500 non-fire CO poisoning deaths and thousands more hospitalizations each year. While many of these casualties result from vehicles or temporary structures, it is the notoriety from fatalities in apartments and publicly accessible buildings that results in code requirements.
For example, a hotel incident in Key West, Fla., in 2006 raised awareness in the state's hospitality industry, while campaigns intended to reduce the number of winter apartment fatalities in northern cities keep enforcement of CO detector requirements a priority in cities such as New York and Chicago.
Sources of carbon monoxideOver the past 40 years, CO has been the subject of numerous studies. These studies describe disbursal properties, chemical behavior, physiological effects, and the statistical totals of deaths and exposures. To determine the optimal detection methods, however, the sources of CO that infiltrate our living spaces need to be understood. CO is a normal and unavoidable gaseous product of combustion with carbon-based fuels. As a result, any facility with equipment fueled by natural gas, coal, wood, heating oil, gasoline, or diesel will generate CO. Table 1 indicates output levels from some CO sources common in and around buildings.
As a known product of combustion, the installation standards for combustion equipment require proper mechanical or natural ventilation of the equipment fumes that contain CO. CO becomes a threat when it accumulates as a result of ventilation equipment that is improperly installed, obstructed, disconnected, in need of maintenance or repair, overwhelmed by improper combustion, or otherwise impaired. If any of these conditions prevent proper exhausting, the production of CO at even the lowest rates indicated in Table 1 can quickly make the occupancy untenable.
While combustion equipment must be properly installed, maintained, and frequently checked for proper operation, proper installation of CO detection is the only effective method of safeguarding the occupants at all times. To be effective, placement of this detection must be completed as prescribed by adopted national or local codes and standards; or as developed from performance-based or risk-assessment methods. The following sections describe several efforts to address these placement issues.
Direction for the use of CO detectors is not summarized by any single code, but is distributed throughout various sections of several recognized national standards. These standards apply only to specific applications and the requirements for CO detection, and are the result of extensive studies over several decades. The intent is to determine where CO detection is effective for the safety and operation of a facility without requiring installation of superfluous devices.
In National Fire Protection Assn . (NFPA) standards, NFPA 720, The Standard for the Installation of Carbon Monoxide Warning Equipment in Dwelling Units, has the most pervasive effect. The scope of this standard acknowledges that most CO casualties occur in the home. And as residential occupants are most vulnerable when asleep, the primary prescriptive requirement of this standard is:
NFPA 720 (2005) %%MDASSML%% 184.108.40.206: A carbon monoxide alarm or detector shall be centrally located outside of each separate sleeping area in the immediate vicinity of the bedrooms.
This standard, however, does not require that the detector be connected to the fire alarm system or other control unit. Detection can be stand-alone detectors:
NFPA 720 (2005) - 4.1.1: The warning functions intended in this standard shall be performed by single- or multiple-station alarms or by detectors connected to a control unit and associated equipment, or any combination thereof.
Finally, this standard requires that all dwelling unit sleeping areas are protected and does not limit the use to dwelling units with carbon fuel combustion equipment. This broad approach is necessary because of the significant CO threat from portable heating and cooking equipment.
NFPA's primary mission is protection against the threat of fire. Standards such as NFPA 101, 2006 edition (Life Safety Code) and NFPA 72, 2007 edition (The National Fire Alarm Code) have become integral to many adopted ordinances and codes. Both of these standards include the requirements of NFPA 720 by reference without specifically calling for CO detection by name. In NFPA 72, CO detectors can be connected to fire alarm systems as supervisory initiating devices and NFPA 101 does not include any requirements beyond those of NFPA 720.
Additional requirements are found in other standards for other specific occupancy types and equipment installations. Several of these NFPA standards indicating required placement are listed in Table 2.
Table 2 does not list all of the NFPA standards with requirements for CO detection. Many other facilities (such as electric power generation stations or hazardous storage) require CO detection or fume-management methods specific to the use of the facility.
Where designers, contractors, and local authorities are required to comply with the codes published by the International Codes Council (ICC), they will find no requirements for CO detection. CO detection placement is not directed in the International Building Code, International Fire Code, or any of the other international code documents. Instead, requirements of the International Residential Code for One- and Two-Family Dwellings (2006) and International Fuel Gas Code (2006) rely upon installation of methods of combustion equipment to be correct. For example:
304.12 Protection from fumes and gases. “Non-direct vent-type appliances shall be located in a mechanical room separated or partitioned off from other areas with provisions for combustion air and dilution air from the outdoors. Direct-vent appliances shall be installed in accordance with the appliance manufacturer's installation instructions.”
As a result, some of the national standards organizations are revisiting detector placement. Most notably, the NFPA Carbon Monoxide Technical Committee has been directed to revise the scope of Standard 720 to cover occupancy types other than dwelling units and provide more generic CO detection requirements.
A key first step was completed with the October 2007 release of “ The Development of a Technical Basis for Carbon Monoxide Detector Siting Research Report .” The report is a publication of The Fire Protection Research Foundation and provides research and recommendations for the placement of CO detectors. Some of the recommendations are certain to be considered for inclusion in future standards and codes.
Any parties interested in participating in the development of these standards is encouraged to become involved through NFPA public comment and code revision cycles .
State and local efforts
Even when state and local governments adopt many of the national standards into their code ordinances, local conditions may give rise to additional CO detection needs. Architects and engineers have specified additional CO detectors necessary for occupant safety. Recently, state and local governing entities amending their own adopted codes with more centralized and more stringent CO detection requirements has been becoming trend. While many jurisdictions and cities, such as Chicago, have had additional CO detection requirements for longer than a decade, the trend is accelerating in such places as New York City and Florida.
In New York City, a new building code based upon the 2003 IBC, is scheduled for implementation July 1. The new code includes an amendment section “908.7 Carbon monoxide alarms and detectors.” This section will require that specific “E,” “I-1,” and “R” occupancies have CO detectors and alarm devices, and these devices must be installed per fire alarm system standards. For “E,” ”I-2,” ”I-4,” and “R-1” occupancies; the alarm notification must be annunciated beyond the detection coverage area. Compliance of these provisions for existing buildings will be required only where fire protection systems are substantially upgraded or where the facility chooses to implement the requirements as part of an overall code equivalency design.
The ”new” New York City code also contains some performance-based options that may require the use of CO detection. The following paragraph is one such example:
NYC MC 404.1 Enclosed parking garages. “Mechanical ventilation systems for enclosed parking garages are not required to operate continuously where the system is arranged to operate automatically upon detection of a concentration of carbon monoxide of 25 ppm by approved automatic detection devices.”
Citing this paragraph, in an enclosed parking garage where environmental air or other reasons make continual exhaust ventilation undesirable or uneconomical, approved CO detection provides an alternate solution.
Farther south, the Florida Building Commission (Florida Building Code CS/CS/SB 1822) has adopted statewide requirements that become effective July 1. New rules require CO detection to be installed public lodging where:
509.211 Every enclosed space or room that contains a ... boiler… which is fired by direct application of energy from the combustion of fuels and … that is located in any portion of a public lodging establishment that also contains sleeping rooms shall be equipped with one or more carbon monoxide sensor devices … Such devices shall be integrated with the public lodging establishment's fire detection system…”
In all new buildings with sleeping facilities and carbon fuel-fired equipment, similar requirements have been adopted:
9B-3.0472 (2) “Every building for which a permit for new construction is issued on or after 7/1/08 and having a fossil-fuel-burning heater or appliance, a fireplace, or an attached garage shall have an operational carbon monoxide alarm installed within 10 ft of each room used for sleeping purposes.”
These measures indicate that Florida recognizes specific CO detection placement requirements are the most direct method of protecting hotel guests, building occupants, and the reputation of state's tourist infrastructure.
Even though CO concerns have been studied and documented for more than 40 years, community awareness and a willingness to apply CO detection through regulation is growing. National standards organizations and local building and fire authorities want more clear, prescriptive requirements for the installation of CO detectors so they are developing the ordinances and policies to implement such requirements. We are certain to see more CO detectors in our homes, and in commercial, industrial, and public buildings. For those with the desire to participate in the process, now is the time to become involved with the appropriate organization or governmental agency.
Gentile is a licensed electrical and fire protection engineer. A graduate of Washington University%%MDASSML%%St. Louis, he is a professional member of the Society of Fire Protection Engineers and on several technical committees of the National Fire Protection Assn.