9VAC5-91-700. Calibration of exhaust gas analyzers

The department shall use, and require for use, gases and containers meeting the following parameters, blends, and specifications in the calibration of exhaust gas analyzers: 1. The calibration gases for standardizing instruments shall conform to the provisions outlined in EPA420-B-04-011. 2. Gas analyzers shall pass a two-point gas calibration for HC, CO, CO 2 and NO, within 72 hours before each test. 3. Gas analyzers shall pass a five-point gas audit for HC, CO, CO 2 , and NO at least two times within 12 months, and each time an analyzer system emissions measurement system, sensor, or other electronic components are repaired or replaced in response to an audit failure. 4. The director may reduce the frequency of calibrations in subdivision 2 of this section and audits in subdivision 3 of this section or both if evidence indicates accuracy would not be adversely affected.