Title 40
SECTION 90.320
90.320 Carbon dioxide analyzer calibration.
§ 90.320 Carbon dioxide analyzer calibration.(a) Prior to its initial use and monthly thereafter, or within one month prior to the certification test, calibrate the NDIR carbon dioxide analyzer as follows:
(1) Follow good engineering practices for instrument start-up and operation. Adjust the analyzer to optimize performance.
(2) Zero the carbon dioxide analyzer with either purified synthetic air or zero-grade nitrogen.
(3) Calibrate on each normally used operating range with carbon dioxide-in-N2 calibration or span gases having nominal concentrations between 10 and 90 percent of that range. A minimum of six evenly spaced points covering at least 80 percent of the 10 to 90 range (64 percent) is required (see following table).
Example calibration points (%) | Acceptable for Calibration? |
---|---|
20, 30, 40, 50, 60, 70 | No, range covered is 50 percent, not 64. |
20, 30, 40, 50, 60, 70, 80, 90 | Yes. |
10, 25, 40, 55, 70, 85 | Yes. |
10, 30, 50, 70, 90 | No, though equally spaced and entire range covered, a minimum of six points are needed. |
(b) The initial and periodic interference, system check, and calibration test procedures specified in 40 CFR part 1065, subparts C and D, may be used in lieu of the procedures in this section.
[60 FR 34598, July 3, 1995, as amended at 70 FR 40449, July 13, 2005]