40 CFR 92.131 - Smoke, data analysis.
The following procedure shall be used to analyze the smoke test data:
(a) Locate each throttle notch test mode, or percent rated power setting test mode. Each test mode starts when the throttle is placed in the mode and ends when the throttle is moved to the succeeding mode. The start of the first idle mode corresponds to the start of the test sequence.
(b) Analyze the smoke trace by means of the following procedure:
(1) Locate the highest reading, and integrate the highest 3-second average reading around it.
(2) Locate and integrate the highest 30-second average reading.
(3) The “steady-state” value is either:
(i) The highest reading occurring more than two minutes after the notch change (excluding peaks lasting less than 5 seconds, caused by such random events as the cycling of an air compressor) if opacity measurements are recorded graphically; or
(ii) The average of the second by second values between 120 and 180 seconds after the notch change if opacity measurements are recorded digitally.
(1) The values determined in paragraph (b) of this section shall be normalized by the following equation:
(2) The normalized opacity values determined in paragraph (c)(1) of this section are the values that are compared to the standards of subpart A of this part for determination of compliance.
(d) This smoke trace analysis may be performed by direct analysis of the recorder traces, or by computer analysis of data collected by automatic data collection equipment.