Pennsylvania Code
Title 67 - TRANSPORTATION
Part I - Department of Transportation
Subpart A - Vehicle Code Provisions
Article VII - Vehicle Characteristics
Chapter 169 - DIESEL SMOKE MEASUREMENT PROCEDURE
Section 169.3 - Definitions

The following words and terms, when used in this chapter, have the following meanings, unless the context clearly indicates otherwise:

Diesel smoke-Particles, including aerosols, suspended in the engine's gaseous exhaust stream of the engine which obscure, reflect or refract light.

Full load power-The power produced, at the speed being considered, when the throttle lever is placed in the maximum fuel position.

Idle speed-The low idle speed of the engine as specified by the manufacturer.

Intermediate speed-The peak torque speed or 60% of rated speed, whichever is higher.

Opacity-That fraction of light transmitted from a source which is prevented from reaching the observer or instrument receiver expressed in percent [opacity = 100%(1-transmittance)].

Peak torque speed-The speed at which the engine develops maximum torque as stated by the manufacturer.

Rated brake power-The maximum brake power output of an engine in horsepower (watts) as stated by the manufacturer, in accordance with SAE J270.

Rated speed-The speed at which the manufacturer specifies the rated brake power of an engine.

Resolution-The minimum distinguishable reading, for a given trace width and scale combination, expressed as a percent of full-scale.

Smoke opacimeter-An optical instrument designed to measure the opacity of diesel exhaust gases. The full flow of exhaust gases passes through the optical unit. A smoke opacimeter is described in SAE J255.

Span-The distance between zero and full-scale deflection of the readout device used with the smoke opacimeter.

Vehicular diesel engine-A compression ignition internal combustion engine of less than 1000 horsepower, 745,700 watts, used to propel on land, nonrail, mobile equipment.