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Understanding CO, Part Two

Picking up where we left off last week, another factor to keep in mind about cabon monoxide generating equipment and draft measurements is that the water column-inch measurement scale we mentioned is a very fine measurement of pressure. One PSI is equal to 27.70 inches of water column, and the draft measurements we mentioned relative to a natural draft appliance are a fraction of a water column inch. The bottom line regarding the proper operation of atmospheric draft equipment such as a water heater or natural draft furnace is that if a given CFM of air is removed from the building due to the conditions mentioned above, then some method of allowing the re-entry of the same amount of air into the building must exist.

An important factor to understand about this situation is that it can be easily written off as extremely rare because the general belief is that if it did happen, somebody would be killed by the CO spill, or at least become gravely ill and wind up in the hospital. As I said last week though, there’s such a thing as low-level CO poisoning, which doesn’t always result in an emergency trip to the hospital. Here are some numbers for you to consider about CO levels in a building, measured in what is referred to as an ambient measurement in PPM (Parts Per Million):

009 PPM: Maximum allowable concentration for continuous 24-hour exposure. In an outdoor situation, this standard is often exceeded in urban areas due to auto exhaust.

10 to 35 PPM: Occupants should be advised of a potential health hazard, particularly to infants, small children, elderly people, and persons with respiratory or heart problems.

35 PPM: Common action level for fire department and other emergency personnel to use self-contained breathing apparatus.

50 PPM: OSHA requirement for maximum allowable concentration for workers continuous exposure in an 8-hour period.

70 PPM: Concentration required for UL2034 alarms to sound when CO at this level is present for as long as 60 minutes.

36 to 99 PPM: Medical alert. Ventilation required.

100 to 200 PPM: Dangerous, a commonly accepted building evacuation standard.

150 PPM: Concentration required for some UL2034 alarms to sound when CO at this level is present for 10 minutes.

220+ PPM: Extremely dangerous.

When you consider the listings above, you immediately recognize a possible health hazard for many people. Note that many alarms do not sound until the CO level in the building is beyond what is known to be a health hazard for the elderly, those with health issues, or children. A fundamental way to consider CO alarms is that they are designed to go off in the event that the carbon monoxide level in the building reaches a point where it would be hazardous for a healthy adult male….based on requirements that were initiated via testing and research involving military personnel.

Another factor to consider regarding a CO alarm is when it was purchased. For the most part, the sensor in the alarm that reacts to the carbon monoxide has a shelf life of approximately two years from the date of manufacture. And most consumers are not aware of this, thinking that if they faithfully replace the battery and press the TEST button on their five-year-old alarm, initiating an audible warning, that they will be protected against a CO spill. The simplest way to explain this process to a customer is that then they press the button, what they’re testing is a button and a power supply only, not the ability of the sensor to function. The only way to properly assess the function of a CO alarm is to use a test kit that includes a plastic bag to surround the alarm and an aerosol container of a material that, once sprayed into the isolated area, will cause the sensor to react.

The technician advising a customer about CO should also be aware of other facts related to the dangers of carbon monoxide. Symptoms are often written off as being other health issues, such as the flu. In one hospital study of 100 patients who requested treatment for what they thought was the flu, 24 were found to be affected by low-level carbon monoxide poisoning. Health care providers, if they are going to confirm carbon monoxide poisoning, must accomplish a carboxyhemoglobin test, which requires taking a blood sample for analysis.

Until next week…

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