The Consumer Products Safety Commission (CPSC) reports that approximately 200 people per year are killed by accidental carbon monoxide (CO) poisoning with an additional 5000 people injured. These deaths and injuries are typically caused by improperly used or malfunctioning equipment aggravated by improvements in building construction which limit the amount of fresh air flowing in to homes and other structures.
While regular maintenance and inspection of gas and oil burning equipment in the home can minimize the potential for exposure to CO gas, the possibility for some type of sudden failure resulting in a potentially life threatening build up of CO gas always exists.
There are a number of different types and brands of carbon monoxide detectors on the market today; They can be most easily characterized by whether they operate on household current or batteries. Underlying this, in most cases, is the type of sensor employed in the detectors operation. Detectors using household current typically employ some type of solid-state sensor which purges itself and resamples for CO on a periodic basis. This cycling of the sensor is the source of its increased power demands. Detectors powered by batteries typically use a passive sensor technology which reacts to the prolonged exposure to carbon monoxide gas.
Regardless of the type of sensor used all detectors sold on the market today should conform to minimum sensitivity and alarm characteristics. These characteristics have been defined and are verified by Underwriters Laboratory in their standard for carbon monoxide detectors UL 2034. This standard was most recently revised in June of 1995 and went into effect in October of 1995. This revision specified additional requirements regarding identification of detector type, low-level (nuisance) alarm sensitivity and alarm silencing. Under no circumstances should one purchase a detector that is not UL listed.
Each of the two types of detectors mentioned previously has applications in the home along with associated advantages and disadvantages. The proper detector for each application or installation should be chosen based on the application requirements and the products specifications. The following are the principle advantages and disadvantages of the two different type detectors:
Characteristic Household Current Battery Operated
Cost $30-50 $30-50
Ease of Installation More difficult- requires Less difficult. Can be
outlet near detector or placed anywhere needed.
'hard wiring'.
Maintenance No maintenance required Requires periodic
during life of product replacement of
(5-10 years). Detector battery/sensor module
sensor becomes more every 2-3 years at a
sensitive with age. cost of ~$20.
Reaction Time/Exposure Gives continuous display Reaction time depends
Level Display of CO levels updated on concentration level
every few minutes. and duration of
exposure. Display
information is limited.
Reset Time Will reset immediately Reset time depends on
once CO problem is exposure concentration
corrected. and duration. May
require removal of
sensor pack. A silence
button, however, is now
provided/required.
The Consumer Product Safety Commission recommends a detector on each floor of a residence. At a minimum, a single detector should be placed on each sleeping floor with an additional detector in the area of any major gas burning appliances such as a furnace or water heater. Installation in these areas ensures rapid detection of any potentially malfunctioning appliances and the ability to hear the alarm from all sleeping areas. In general, carbon monoxide detectors should be placed high (near the ceiling) for most effective use. Detectors should also not be placed within five feet of gas fueled appliances or near cooking or bathing areas. Consult the manufacturers installation instructions for proper placement of a detector within a given area.
There are many conditions which can cause a carbon monoxide detector to alarm. Most are preventable and few are actually life threatening. Ideally through proper placement of the detector and education of the users the number of preventable calls can be minimized and activation will only occur in the more serious situations.
Preventable causes of CO alarm activation and the recommended preventive action are as follows:
Cause Preventive Action
Inadequate fresh air venting of the Have a heating contractor install a
home. fresh air makeup system in the home
Running gas powered equipment or Gas powered equipment or vehicles
automobiles in a home or garage should never be operated within a
home or garage- even if the garage
door is open. Since most homes are
typically at a lower pressure
relative to outside air, the gas can
actually be drawn into the home.
Charcoal grilling in the home or Charcoal grilling is a tremendous
garage. producer of carbon monoxide gas.
Charcoal grills should never be
operated in the home.
Malfunctioning appliances or All fuel burning appliances or
equipment in the home. equipment in the home needs periodic
inspection and preventive
maintenance. While all fuel burning
appliances will produce some CO gas,
regular preventive maintenance can
keep this to a minimum.
Malfunctioning or overly sensitive Buy only UL Listed alarms conforming
alarm. to the latest revision (June 1995)
of UL standard 2034. This revision
includes new requirements to minimize
nuisance alarms.
While many causes can be prevented others can not and may occur unpredictably. Not only are these problems harder to predict but they also tend to be more serious in nature. Examples of these type problems are:
Minimizing preventable events allows everyone to take other less preventable and predictable events more seriously.
Several manufacturers of carbon monoxide detectors offer toll free numbers for additional information regarding their products. These numbers are as follows:
Manufacturer Number American Sensors 800-387-4219 Enzone 800-448-0535 First Alert 800-323-9005 Jameson 800-779-1719 Nighthawk 800-880-6788 Quantum 800-432-5599 Radio Shack Contact your local store S-Tech 800-643-5377
Additional information with product ratings is contained in the July 1995 Consumer Reports issue on home safety products. One word of note regarding the ratings in this issue- the products tested have probably since be replaced by updated models conforming to the revised UL 2034 standard which took effect in October 1995. Check with the manufacturer for current information.
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