(a) Warming-up time. The warming-up time should be according to the recommendations of the manufacturer. If not specified, a minimum of two hours shall be allowed for warming up the analyzers.

(b) NDIR and HFID analyzer. The NDIR analyzer shall be tuned and maintained according to the instrument manufacturer's instructions. The combustion flame of the HFID analyzer shall be optimized in order to meet the specifications in §89.319(b)(2).

(c) Zero setting and calibration.

(1) Using purified synthetic air (or nitrogen), the CO, CO2, NOX. and HC analyzers shall be set at zero.

(2) Introduce the appropriate calibration gases to the analyzers and the values recorded. The same gas flow rates shall be used as when sampling exhaust.

(d) Rechecking of zero setting. The zero setting shall be rechecked and the procedure described in paragraph (c) of this section repeated, if necessary.

[59 FR 31335, June 17, 1994. Redesignated at 63 FR 56995, Oct. 23, 1998]