Carbon Monoxide Detectors


Carbon Monoxide Detectors: What You Need to Know

Recently, a few residents contacted the fire department, regarding the difference between standard carbon monoxide (CO) detectors available at hardware and home improvement stores, and the low-level carbon monoxide detectors being sold by local heating and cooling contractors. The overall question being if one is better than the other. The better question to ask is whether or not one has a more appropriate application than the other. First, let’s define carbon monoxide, understand how it’s produced, and how it affects the body.

Carbon monoxide is a colorless, tasteless, odorless, gas that is a byproduct of incomplete combustion. Basically speaking, any appliance, (to include natural or gas fireplaces, barbecue grills, vehicle exhaust, etc…) that has a flame, produces CO in varying levels. In a high enough concentration, it can be poisonous. Some appliances produce a very low concentration of carbon monoxide (natural gas stoves) while others produce a much higher concentration (barbecue grills, wood burning stoves). This is why certain appliances are vented to the outside, such as a gas hot water heater or furnace. CO poisons the body by replacing oxygen molecules in the bloodstream with carbon monoxide molecules. A high enough concentration of CO causes a poisoning of the tissues which impairs or destroys the body’s normal respiratory, cardiac, and neurological functions.

 Even a candle produces carbon monoxide. But the concentration of CO is so miniscule, that it easily dissipates from the home through the natural air flow.

Standard Carbon Monoxide Detectors

For healthy persons, the variety of carbon monoxide detectors found at hardware and home improvement stores, meet the industry standard for alerting occupants of the presence of concerning levels of carbon monoxide. Choosing a detector that has been certified by Underwriters Laboratory (UL), will assure that the detector meets, or exceeds, the industry standard. These detectors provide an audible alert prior to carbon monoxide levels reaching dangerous levels. These detectors have a tiered alarm activation dependent on the concentration level of CO over a period of time. As a rule, they are certified to activate within one to four hours of being exposed to a consistent level of 70 parts per million (PPM), activate in less than one hour of being exposed to a consistent level of 150 PPM, and activate in less than fifteen minutes of being exposed to a consistent level of 400 PPM.

 CO detectors with digital readouts will display a number when the CO level reaches 30 PPM or higher, but the audible alarm will not activate until 70 PPM. The display provides early warning that something is wrong before the audible alarm ever activates.

Most healthy persons start to experience the initial symptoms of CO poisoning after one to two hours of consistent exposure to 200 PPM or more. The initial symptoms of CO poisoning are:

  • Headache
  • Nausea / Vomiting
  • Fatigue

Symptoms of moderate to severe exposure to high concentrations of CO (400 PPM and higher, consistently over a one to two hour period) are:

  • Severe Headache
  • Drowsiness / Confusion
  • Fast Heart Rate
  • Coma, and eventually, Death

Low-Level Carbon Monoxide Detectors

For persons suffering from chronic respiratory or cardiac diseases, such as chronic bronchitis, emphysema, congestive heart failure, or coronary artery disease, low-level carbon monoxide detectors provide the benefit of early detection and alert. Persons with these diseases are more sensitive to the effects of lower concentrations of CO than are healthy persons. These detectors constantly monitor the air, and also have a tiered alarm activation. As a rule, they are certified to activate after five minutes of being exposed to a consistent level of 15-35 parts per million (PPM), and activate after thirty seconds of being exposed to a consistent level of 70 PPM or greater.

 These alarms are more expensive (two to three times the cost of standard CO detectors), and are sold and installed by professional heating and cooling contractors.

Frequently Asked Questions

  • Which Alarm is Right for Me, and Where Should I Place it?

Unless you have one of the diseases listed above, or you have been told by a physician that you or a person staying in your home, are susceptible to lower concentrations of carbon monoxide, a standard CO alarm is more than adequate.

The standard alarms come in three basic power formats; battery only, plug-in, or plug-in with battery back-up. They each have their benefits, depending on where you’ll be placing the detector. Some hallways don’t have electrical outlets, so this would leave battery powered as the only option.  Each manufacturer has their own recommendations in the instructions as to where the detector should be placed, and you should follow their guidelines.

 If you are considering buying a CO alarm that works by plugging it into an electrical outlet, make sure it has a battery back-up in case of a power outage. Alternate sources of heat and electricity (generators) can produce an unexpected build-up of CO in living spaces. Continuous detection during these times is crucial!

  •  How Many Should I Have, and Where Should They be Placed?

The number and placement of carbon monoxide detectors is very similar to what is recommended for smoke detectors; one on every level, with at least one – especially if it’s the only one – near the sleeping area, preferably the hallway near the master bedroom. This provides protection when you are the most vulnerable; when you’re asleep. Carbon monoxide is known as the “silent killer’ because it cannot be smelled, tasted, or seen. Like smoke detectors in a fire, early detection of carbon monoxide is tantamount to survival.

 Avoid placing carbon monoxide detectors in areas where “nuisance alarms” can be prevalent, such as near attached garage entryway doors, or near gas appliances or fire places. It’s not uncommon for there to be residual CO in the air for a short period of time when gas appliances – especially automobiles – are started, before natural ventilation or drafting dissipates the CO.

  •  What Should I Do if My CO Alarm Goes Off?

First, verify that it is the CO alarm going off. If it has a digital display, try and remember the number (PPM). Calmly gather up all persons and pets from the home and go to a warm, dry place, such as a neighbor’s house or vehicle. Call 911 and explain that your CO detector is going off, and provide the PPM level if you have it. The fire department will be sent to check the house and attempt to locate the source using sensitive detection devices.

 If the alarm activates DO NOT panic. Even at CO levels of up to 800 PPM, healthy adults still have up to 45 minutes before the effects of CO poisoning can debilitate them.

  • How Often Should I Replace the Battery, and When Should the Detector Be Replaced?

 The battery, whether battery-powered or battery back-up, should be changed annually, just like smoke detector batteries. Pick a date that is easy to remember, such as with the spring or fall time change. Detectors should be replaced between five to ten years. Manufacturers often specify when a detector should be replaced in their warranty information or installation instructions.

 Perform a function check on the detector every so often by pressing and holding the test button. If the alarm does not activate; it’s time for a replacement, or a new battery.

  •  What is the Difference Between a Low-Battery Alarm and an Alarm Activation Due to CO?

Carbon monoxide detectors, like smoke detectors, have a built-in battery power sensor that will emit an intermittent “chirp” when the battery is low. This chirp will occur every few minutes. If the detector has a digital readout, it with either display “Lb” or “BAT” if the battery is low. An activation of the detector due to the presence of CO will result in a consistent, frequent, loud audible alarm.

  •  How Should I Clean my CO Detector?

The instructions included with your detector will have routine maintenance guidelines. If you’ve lost the instruction booklet, you can often find it on the manufacturer’s website. Vacuuming monthly, with a residential vacuum wand attachment, is generally the only required cleaning. Avoid spraying cleaning chemicals on the detector, as this can damage or destroy the sensing mechanisms. Never paint or otherwise alter the detector.

If you have any questions regarding carbon monoxide or smoke detectors, or to schedule a courtesy fire safety inspection of your home, please contact Independence Township Fire Department at (248)625-1924.