Carbon Monoxide Alarms

Submitted by KimChristensen on Sun, 03/30/2014 - 13:01

Carbon monoxide alarms- Carbon monoxide (CO) gas is a colorless, odorless and tasteless gas that is present in automobile exhaust fumes and in the combustion gases from fuel burning appliances (furnaces, open flames, space heaters, water heaters or fireplaces burning natural gas, propane or wood); especially when incomplete combustion is occurring. Incomplete combustion can occur when there is a malfunction of the appliance, or there is inadequate combustion air available, or if the appliance flue is stopped up. Detection of carbon monoxide in a home is impossible without a CO alarm. CO gas is poisonous and in high enough concentrations causes sickness and death. CO replaces the oxygen in your blood, and in fact, the hemoglobin (oxygen carrying component) in your blood has an affinity for CO about 200 times greater than for oxygen. If there is any CO gas in your house your bloodstream will absorb it. Symptoms of CO poisoning include- headache, nausea, weakness and sleepiness. Many years ago, my parents awoke on a cold winter morning with the realization that something was very wrong. The furnace was malfunctioning and producing CO and other combustion gases. They both had pronounced headaches and a profound feeling of sleepiness, and it was all my dad could do to fall out of bed and crawl to the front door. He stuck his head outside for a few moments and quickly came to. Then he was able to turn off the furnace and open some windows. You may have heard about a man who died in a Lubbock motel recently due to carbon monoxide poisoning.

CO alarms are recommended. The previous examples are some of the reasons that CO alarms are recommended for all homes that have an attached garage or any fuel burning appliances. CO alarms are now required in new construction in Texas and many other states. In existing homes they are a safety upgrade. CO alarms can be purchased by themselves or in combination with smoke alarms. The stand-alone CO alarms retail for about $15 to $60 dollars and are widely available at home improvement and other stores. Unfortunately, the sensors in these alarms only last for approximately 5 to 10 years and then the alarms need to be replaced. Many of the new CO alarms have long life batteries that will last for the life of the alarm, so you won't have to mess with changing batteries. Other types are powered by the household electrical supply. Some of the alarms will tell you when it is time to replace them.

Types of CO alarms- Most alarms sound an audible alarm but there are some wireless alarms that can vibrate pillow pads, light strobe lights or signal a remote handset. Some CO alarms have a digital readout that indicates the CO concentration in parts per million. These types of alarms cost more than more basic types. The 4 basic types of alarms are- Opto-chemical, Semiconductor, Biomimetic and Electro-chemical. 

     Opto-chemical alarms are the cheapest but they are the only type that doesn't produce an alarm (a colored chemical changes color if CO gas is present) thus these "alarms" offer the lowest degree of protection.

     Semiconductor alarms use a sensor that needs to be heated to about 400* C in order to work. Because of the large power demand these alarms are usually powered by household electricity instead of batteries. The superior performance of the remaining 2 types of alarms is beginning to replace these alarms.

     Biomimetic alarms last for about 6 years if powered by lithium batteries and were the first mass marketed CO alarms. They are the most reliable according to a report from Lawrence Berkeley National Laboratory. Also, this technology is the only one that tested false alarm free, which makes them popular in larger locations such as hospitals, apartments and motels where the cost of a false alarm is high. But because these alarms cost more than the other types they are used mostly in the higher end areas and in RV's. 

     Electro-chemical alarms use a fuel cell as a sensor. These alarms are very accurate, use a low amount of power because they operate at room temperature and the sensors have a long life (usually 5 years or more). The cost of these alarms was high initially but has come down. These alarms are now the most popular alarms in the USA and Europe.

Alarm placement- If you are installing only 1 CO alarm, the Consumer Product Safety Commission recommends that it be located near the bedrooms so you will be most likely to hear it if it goes off. If there are separate bedroom areas, an alarm just outside of each area would be helpful. Additional alarms on every level of the house and/ or in every bedroom provide additional protection, but even 1 or 2 alarms give much better protection than none (most homes don't have any CO alarms). CO alarms should not be placed directly above or beside fuel burning appliances to avoid false alarms. These appliances sometimes give off small amounts of CO especially when they first turn on. Therefore, stay about 15 feet or more away from the appliances and from humid areas such as bathrooms. CO gas has almost the exact same density as air and therefore is not lighter or heavier than air. So alarms placed at ceiling level or near the floor should all work. However, having said that, sometimes the CO gas from a malfunctioning appliance is contained in the warm air rising from the appliance. Therefore some people think that placing the alarms at or near ceiling level may give an earlier warning. Be sure to read the manufacturers' placement recommendations. . . . And sleep peacefully knowing you are protected. --- Kim Christensen TREC 20358
Submitted by KimChristensen on Sun, 03/30/2014 - 13:01