§ 169.4. Smoke emission test.
The following sequence of operations shall be performed during engine dynamometer testing for smoke emissions:
(1) Control the temperature of the air supplied to the engine to between 80° and 90°F (27° and 32°C). Test only when the observed barometric pressure is between 28.5 and 30.5 inches (724 and 725 millimeters) of mercury in the test area. Starting with an engine at operating temperature, operate the engine at the condition of maximum mass fuel flow, adjust the intake air restriction to within 1 inch (25.4 millimeters) of water of the maximum recommended by the manufacturer and adjust the exhaust system back pressure to within .2 inch (5.1 millimeters) of mercury of the maximum recommended by the manufacturer. Measure and record maximum observed power, fuel rate, engine speed, intake air temperature, intake air restriction and exhaust back pressure.
(2) Operate the engine at the intermediate speed. Measure and record maximum observed torque, fuel rate, engine speed, intake air temperature, intake air restriction and exhaust back pressure. Determine by experiment, if not previously determined, the preset loads required by the provisions of § 169.5 (relating to smoke test cycle).
(3) Switch on the smoke opacimeter. Allow for the meter circuit to stabilize according to the instruction of the manufacturer. Check the linearity of the meter according to the provisions of § 169.8 (a)(1) and (3) (relating to instrument checks). Mount the smoke opacimeter in accordance with the provisions of § 169.7(b) (relating to equipment and instrumentation) so that the natural flow of the exhaust stream is not disturbed by the meter, the mounting fixture or a ventilation system.
(4) Pass the exhaust flow through the smoke opacimeter so that the opacity of the exhaust plume may be measured.
(5) Operate the engine at maximum power for 10 minutes or until the engine coolant, oil pressures and temperatures are stabilized.
(6) Discontinue passing the exhaust gas stream through the meter. Set the zero and span of the smoke opacimeter recorder.
(7) Operate the engine in the manner required by the provisions of § 169.5. Continuously record smoke opacity and engine speed on a strip chart recorder or other appropriate instrument. The chart speed shall be at least 1 inch (25 millimeters) per minute during the idle mode and at least 15 inches (381 millimeters) per minute during acceleration and lugging modes.
(8) Repeat the procedures as contained in the provisions of § 169.5 (a)—(d) until the entire cycle has been run three consecutive times. If the acceleration and lugging modes have been performed within the tolerances specified in the provisions of § 169.5, then the tests may be terminated at this time. If not, then the test procedure shall be rerun until data have been obtained within the specified limits.
(9) Within 1 minute after completion of the requirements of paragraph (8), recheck the calibration of the smoke opacimeter as described in paragraph (6). If either zero or span drift is in excess of 2% opacity, the test results should be considered invalid.
Source The provisions of this § 169.4 adopted August 26, 1977, effective August 27, 1977, 7 Pa.B. 2432.
Cross References This section cited in 67 Pa. Code § 169.5 (relating to smoke test cycle); and 67 Pa. Code § 169.7 (relating to equipment and instrumentation).
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