§ 169.5. Smoke test cycle.
A smoke emissions test specified in the provisions of § 169.4 (relating to smoke emission test) is conducted according to the following sequence:
(1) Idle mode. Idle the engine for 1.5 to 2 minutes at the recommended low idle speed of the manufacturer with the dynamometer controls set to provide minimum load by turning the load switch to the ‘‘off’’ position or by adjusting the controls to the minimum load position.
(2) Acceleration mode. Test procedures shall be as follows:
(i) Accelerate the engine at full throttle against inertia or alternately against a preprogrammed dynamometer load such that the engine speed increases to 85—90% of rated speed in 3.5 to 5.5 seconds. For maximum repeatability on turbocharged engines with more than 1.5 pressure ratio, this should be held to closer limits. The acceleration should be kept linear within plus or minus 100 revolutions per minute.
(ii) When the engine reaches 85—90% of rated speed, rapidly close the throttle and remove the dynamometer load, if any. Apply the preset load required to perform the acceleration in subparagraph (iii). Allow the engine speed to drop to the intermediate speed within plus or minus 100 revolutions per minute.
(iii) Rapidly move the throttle to the full throttle position and accelerate the engine against a dynamometer load schedule such that the engine speed reaches 95—100% of rated speed in 10, plus or minus 2, seconds.
(3) Rated speed mode. Test procedures shall be as follows:
(i) Proceeding from the acceleration mode, adjust the dynamometer controls to permit the engine to develop full load power at rated speed.
(ii) Allow the engine to operate for 1 minute after the load and speed have stabilized at full load power at rated speed.
(4) Lugging mode. Adjust the dynamometer controls without changing the throttle position to slow the engine gradually to the intermediate speed. Perform this engine lugging operation smoothly over a period of 35, plus or minus 5, seconds. The slowing rate of the engine should be kept linear within plus or minus 100 revolutions per minute.
(5) Intermediate speed mode. Allow the engine to operate at full load power at the intermediate speed for one minute after the load and speed have stabilized.
(6) Engine unloading. After completion of the lugging and intermediate speed modes, the dynamometer and engine shall be returned to the idle condition described in paragraph (1). The zero and span of the smoke opacimeter may be checked and reset if necessary. If either zero or span drift is in excess of 2%, the test results should be considered invalid.
Source The provisions of this § 169.5 adopted August 26, 1977, effective August 27, 1977, 7 Pa.B. 2432.
Cross References This section cited in 67 Pa. Code § 169.4 (relating to smoke emission test); 67 Pa. Code § 169.7 (relating to equipment and instrumentation); and 67 Pa. Code § 169.9 (relating to chart reading—general engine applications).
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