Section 86.516-90 - Calibrations, frequency and overview(a) Calibrations shall be performed as specified in §§ 86.517 through 86.526 .(c) At least monthly or after any maintenance which could alter calibration, the following calibrations and checks shall be performed:(1) Calibrate the hydrocarbon analyzer, methane analyzer, carbon dioxide analyzer, carbon monoxide analyzer, and oxides of nitrogen analyzer (certain analyzers may require more frequent calibration depending on particular equipment and uses).(2) Calibrate the dynamometer. If the dynamometer receives a weekly performance check (and remains within calibration), the monthly calibration need not be performed.(3) Check the oxides of nitrogen converter efficiency.(d) At least weekly or after any maintenance which could alter calibration, the following calibrations and checks shall be performed: (2) Perform a CVS system verification, and(3) Run a performance check on the dynamometer. This check may be omitted if the dynamometer has been calibrated within the preceding month.(e) The CVS positive displacement pump or Critical Flow Venturi shall be calibrated following initial installation, major maintenance or as necessary when indicated by the CVS system verification (described in § 86.519 ).(f) Sample conditioning columns, if used in the CO analyzer train, should be checked at a frequency consistent with observed column life or when the indicator of the column packing begins to show deterioration.54 FR 14546, Apr. 11, 1989, as amended at 58 FR 58423, Nov. 1, 1993; 60 FR 34354, June 30, 1995