(a) Allow a minimum of 30 minutes warm-up in the stand-by or operating mode prior to spanning the analyzers.
(b) Replace or clean the filter elements and then vacuum leak check the system, § 86.328(a). A pressure leak check is also permitted per § 86.328(b). Allow the heated sample line, filters, and pumps to reach operating temperature.
(c) Perform the following system checks:
(1) If a stainless steel NO2 to NO converter is used, prior to gasoline-fueled engine tests, purge the converter with air (zero-grade air, room air, or O2) for a minimum of 30 minutes. The converter must be at operational temperature while purging.
(2) Check the sample-line temperature (see § 86.310).
(3) Check the system response time (see § 86.329). System response time may be applied from the most recent check of response time if all of the following are met:
(i) The flow rate for each flow meter is equal to or greater than the flow rate recorded in § 86.329(b)(1)(ii).
(ii) For analyzers with capillaries, the response time from the sample/span valve is measured using in-use pressures and bypass flows (see § 86.329(b)(2)).
(iii) The response time measured in step (ii) is equal to or less than the response time determined in § 86.329(b)(2)(vii).
(4) A hang-up check is permitted.
(5) A converter-efficiency check is permitted. The check need not conform to § 86.332(b). The test procedure may be aborted at this point in the procedure in order to repair the NO2 to NO converter. If the test is aborted, the converter must pass the efficiency check described in § 86.332(b) prior to starting the dynamometer test run.
(d) Introduce the zero-grade gases at the same flow rates and pressures used to calibrate the analyzers and zero the analyzers on the lowest anticipated range that will be used during the test. Immediately prior to each test (segment, for Diesel engines), obtain a stable zero for each anticipated range that will be used during the test.
(e) Introduce span gases to the instruments under the same flow conditions as were used for the zero gases. Adjust the instrument gains on the lowest range that will be used to give the desired value. Span gases should have a concentration greater than 70 percent of full scale for each range used. Immediately prior to each test and also prior to each segment of the Diesel test, record the response to the span gas and the span-gas concentration for each range that will be used during the test.
(f)Check the zero responses. If they have changed more than 0.5 percent of full scale, repeat paragraphs (d) and (e) of this section.
(g) Check system flow rates and pressures. Note the values of gauges G3 and G4 for reference during the test.
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