1. a) All equipment utilized for on-road remote sensing emission measurement shall be maintained and calibrated according to the manufacturer's specifications.

2. b) The accuracy of the Infrared SDM shall be verified by measuring the concentration of tri-blend (CO₂, HC, CO) calibration gas released from a specially modified vehicle. A two point gas calibration procedure shall be followed. The span shall be accomplished at the following pair of span points:

   300 – ppm propane (HC)

   1.0 – percent CO

   6.0 – percent CO₂

   1200 – ppm propane (HC)

   4.0 – percent CO

   12.0 – percent CO₂

   The Infrared SDM shall measure the span gas within the allowable tolerance range specified in Section 276.507(b) of this Part.

(Source: Added at 22 Ill. Reg. 18867, effective September 28, 1998)