The inspection procedures include measuring for fuel gas and carbon monoxide (CO) and will require the use of a combustible gas detector (CGD) and a CO detector. It is recommended that both types of detectors be listed. Prior to any inspection, the detectors should be calibrated or tested in accordance with the manufacturer's instructions. In addition, it is recommended that the detectors have the following minimum specifications.
- Gas Detector: The CGD should be capable of
indicating the presence of the type of fuel gas for
which it is to be used (e.g. natural gas or propane). The combustible gas detector should be capable of the
- PPM: Numeric display with a parts per million (ppm) scale from 1 ppm to 900 ppm in 1 ppm increments.
- LEL: Numeric display with a percent lower explosive limit (% LEL) scale from O percent to 100 percent in 1 percent increments.
- Audio: An audio sound feature to locate leaks.
- CO Detector: The CO detector should be capable of
the following functions and have a numeric display
scale as follows:
- PPM: For measuring ambient room and appliance emissions a display scale in parts per million (ppm) from O to 1,000 ppm in 1 ppm increments.
- Alarm: A sound alarm function where hazardous levels of ambient CO is found (see D.2 for alarm levels)
- Air Free: Capable of converting CO measurements to an air free level in ppm. Where a CO detector is used without an air free conversion function, the CO air free can be calculated in accordance with footnote 3 in Table D.6.
|Central Furnace (all categories)||400 ppm1 air free2, 3|
|Floor Furnace||400 ppm air free|
|Gravity Furnace||400 ppm air free|
|Wall Furnace (BIV)||200 ppm air free|
|Wall Furnace (Direct Vent)||400 ppm air free|
|Vented Room Heater||200 ppm air free|
|Vent-Free Room Heater||200 ppm air free|
|Water Heater||200 ppm air free|
|Oven/Boiler||225 ppm as measured|
|Top Burner||25 ppm as measured (per burner)|
|Clothes Dryer||400 ppm air free|
|Refrigerator||25 ppm as measured|
|Gas Log (gas fireplace)||25 ppm as measured in vent|
|Gas Log (installed in wood
|400 ppm air free in firebox|
- Parts per million
- Air free emission levels are based on a mathematical equation (involving
carbon monoxide and oxygen or carbon dioxide readings) to convert an
actual diluted flue gas carbon monoxide testing sample to an undiluted air
free flue gas carbon monoxide level utilized in the appliance certification
standards. For natural gas or propane, using as-measured CO ppm and O2
Where: COAFppm = Carbon monoxide, air-free ppm COppm = As-measured combustion gas carbon monoxide ppm O2 = Percentage of oxygen in combustion gas, as a percentage
- An alternate method of calculating the CO air free when access to an
oxygen meter is not available:
Where: UCO2 = Ultimate concentration of carbon dioxide for the fuel being burned in percent for natural gas (12.2 percent) and propane(14.0 percent) CO2 = Measured concentration of carbon dioxide in combustion products in percent CO = Measured concentration of carbon monoxide in combustion products in percent