(a) Applicability. The requirements of this subsection apply to short tests conducted under Emissions Performance Warranty through December 31, 1993. The requirements of § 85.2233 apply concurrently until December 31, 1993, after which the requirements of § 85.2233 are solely in effect. The following exceptions apply: In a state where the Administrator has approved a SIP revision providing for implementation of a basic centralized program meeting the requirements of part 51, subpart S of this chapter, according to the schedule specified in § 51.373 of this chapter, the requirements of this section are concurrently in effect until June 30, 1994 for 1995 and earlier model year vehicles or engines; in a state where the Administrator has approved a SIP revision providing for implementation of an enhanced program meeting the requirements of part 51, subpart S of this chapter, according to the schedule specified in § 51.373 of this chapter, the requirements of this section are concurrently in effect until December 31, 1995 for 1995 and earlier model year vehicles or engines.
(b) Equipment shall be calibrated in accordance with the manufacturers' instructions.
(c) Hourly checks. Within one hour prior to a test, the analyzers shall be zeroed and spanned. Ambient air is acceptable as a zero gas; an electrical span check is acceptable. Zero and span checks shall be made on the lowest range capable of reading the short test standard. Analyzers that perform an automatic zero/span adjustment every time a test sequence is initiated are considered to meet the hourly checks.
(d) Daily checks. Within eight hours prior to a loaded test, the dynamometer shall be checked for proper power absorber settings.
(e) Weekly checks—(1) Leak check. For analyzers with a separate calibration or span port, CO readings using the span gas through the probe and through the calibration port shall be made and compared; discrepancies of over 3% shall require repair of leaks. No analyzer adjustments shall be permitted during this check. The leak check and the following gas span check may be combined into one operation.
(2) Gas span check. Within one week of the test, the analyzers shall have been spanned using calibration gases which meet the requirements in paragraph (d)(4) of this section and shall not have been readjusted since to a non-conforming gas. If the analyzer reads the span gas within 2% of the span gas value or within .05% CO and 6 ppm HC (use the larger of the two tolerances), then no adjustment of the analyzer is needed. For this check the span gas may be introduced either through the calibration port (if so equipped) or through the probe. This paragraph does not prevent those who wish to always adjust the analyzer to the exact span value from doing so.
(3) Gas span adjustment. If the analyzer fails to meet the gas span check specifications, then the analyzer shall be adjusted by the following procedures:
(i) For analyzers without a calibration port, perform a simple leak check (e.g., cap the probe). Repair any leaks before continuing with this procedure. Introduce the span gas through the probe for this adjustment.
(ii) For analyzers with a calibration port, introduce the span gas through the port for this adjustment.
(iii) Perform a zero adjustment and a flowing span gas adjustment. Iterate between span and zero, as necessary, to obtain stable readings within the gas span check specifications.
(iv) Check the electrical span without changing the zero or span adjustments set in step (iii). If the electrical span does not match the electrical span line or voltage level, locate the potentiometer that controls the relationship between the gas span and the electrical span. Adjust this control until the electrical span target is achieved.
(v) Following this procedure, if the gas span value cannot be held within the 2% tolerance (or .05% CO and 6 ppm HC) while also meeting the electrical span criteria, then the analysis system and calibration bottle shall be removed from service until the problem is resolved and the adjustment tolerance met.
(vi) Automatic analyzers that perform either a substantially similar adjustment procedure or mathematical correction procedure are considered to meet this adjustment procedure.
(4) Span gases. The span gas used for the weekly check shall be traceable to NBS standards ±2% and have concentrations either:
(i) Between the standards specified in this subpart and the jurisdiction's inspection standards for the 1981 model year light duty vehicles, or
(ii) Within −50% to 100% of the standards in this subpart.
(f) Other checks. In addition to performing span and leak checks on a periodic basis, these checks shall also be used to verify system performance under the following special circumstances.
(1) Gas span check. Within one week of the test, the analyzers must have been spanned using calibration gases which met the requirements in paragraph (e)(4) of this section and must not have been readjusted since to a non-conforming gas. If the analyzer reads the span gas within two percent of the span gas value or within .05 percent of the CO and 6 ppm HC (use the larger of the two tolerances), then no adjustment of the analyzer is needed. (However, adjusting the analyzer to the exact span value is not precluded.) For this check the span gas may be introduced either through the calibration port, if so equipped, or through the probe.
(2) Leak checks. Each time the sample line integrity is broken, a leak check shall be performed prior to testing. A simple vacuum leak check (i.e., block the probe and check for low flow) is considered acceptable for these non-periodic checks.
[49 FR 24323, June 12, 1984. Redesignated and amended at 58 FR 58403, 58415, Nov. 1, 1993]
Title 40 published on 2012-07-01
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