As you test for Carbon Monoxide and measure combustion efficiency, you’ll begin to gather test numbers. Let’s take a look at some of the standards, and what test results mean under different testing conditions.
CARBON MONOXIDE IN AN OCCUPIED SPACE
Reactions to various levels of CO will differ from one person to another, but the following concentrations and symptoms are typical. Small children and older people will show symptoms faster and at lower levels. These CO level symptoms are typical for healthy adults only.
- 1-9 PPM – Maximum allowable short-term exposure in a living area.
- 10-34 PPM – Is considered normal from traffic or an unvented stove, but testing should be done to identify the source of the CO and correct it. Long-term exposures to low levels cause far more damage than the few well publicized effects of high-level exposure.
- 35 PPM – Is the maximum allowable concentration allowable for an 8-hour period per OSHA.
- From 36-99 PPM – Turn off all combustion appliances and open windows. Infant deaths have occurred at these levels.
- At 100 PPM – Discontinue testing and Contact 911. CO levels can increase very rapidly causing extremely unsafe conditions.
- 200 PPM – Will produce headache, tiredness, dizziness and nausea after 2-3 hours
- 800 PPM – Will cause unconsciousness in less than 2 hours, and death in 2-3 hours
- 1600 PPM – Will cause death in 1 hour, symptoms will appear immediately
- 12800 PPM – Will cause death in 1-3 minutes.
Download this information in a handy chart form and print one out for each of your technicians and installers.
The chart is located at:
CARBON MONOXIDE AND COMBUSTION ANALYSIS
When taking CO readings to evaluate combustion, test in flues and above combustion chambers. This will give you an accurate reading as you will be measuring before the flue gases are diluted with air from a draft hood or a barometric damper. In order to correctly interpret the combustion process, WHEN to test, is as critical as WHERE to test.
Always test the space around the furnace as you enter a building to assure your safety.
Test CO levels upon burner light-off. CO levels should not exceed 400 PPM in the first few minutes of operation and should drop quickly. Higher levels indicate pilot or burner problems and need immediate adjustment or repair.
Within 5 minutes, CO levels should drop and read from 10 -100 PPM. Readings should continue to be taken in each chamber over the next five minutes of operation. This testing is done to assure that CO readings remain stable. Stable readings usually indicate that the combustion process and combustion air and venting systems are operating properly, and the furnace is operating safely. If CO readings begin to rise, even slowly, there’s an indication of a problem. There are times it takes hours for readings to become unstable.
Readings over 400 PPM are an indication of severe combustion problems that cause unsafe conditions. Unless repairs are made, the furnace must be shut off.
Readings under 400 PPM are also unsafe, but if the readings remain stable, the furnace can operate minimally if there is no CO spillage into the space. Repairs should be made as soon as possible.
When the furnace shuts down, CO readings should reduce steadily until they read zero during the following minute. If there is any increase in CO for more than 30 seconds, you probably have a leaky gas valve.
Check your NCI Inc. CO and Combustion manuals to determine test levels, methods and frequency for other types of appliances and fuels. Also study other readings such as Oxygen, CO2, Temperature and Draft to master combustion improvement, efficiency and maximize BTU output.