D.1.5 Instruments

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.

1. 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 following:
   1. PPM: Numeric display with a parts per million (ppm) scale from 1 ppm to 900 ppm in 1 ppm increments.
   2. LEL: Numeric display with a percent lower explosive limit (% LEL) scale from 0 percent to 100 percent in 1 percent increments.
   3. Audio: An audio sound feature to locate leaks.
2. CO Detector: The CO detector should be capable of the following functions and have a numeric display scale as follows:
   1. PPM: For measuring ambient room and appliance emissions a display scale in parts per million (ppm) from 0 to 1,000 ppm in 1 ppm increments.
   2. Alarm: A sound alarm function where hazardous levels of ambient CO is found (see D.2 for alarm levels)
   3. 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.