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This SAE Recommended Practice is intended for use as a test procedure to determine the gaseous emission levels of diesel engines. Its purpose is to provide a map of an engine's emissions characteristics which, through use of the proper weighting factors, can be used as a measure of that engine's emission levels under various applications. The emission results for hydrocarbons, nitrogen oxides, carbon monoxide, and carbon dioxide are expressed in units of grams per kilowatt hour (grams/brake horsepower hour) and represent the mass rate of emissions per unit of work accomplished. The emissions are measured in accordance with SAE Recommended Practices J177, J215, and J244 using nondispersive infrared equipment for CO and CO2, a heated flame ionization analyzer for HC, and a high performance NDIR or a chemiluminescence analyzer for NOx. All emissions are measured during steady-state engine operation.

The method presented applies to the analysis of the indicated constituents in diesel engine exhaust, or vehicles using diesel engines, when operating at steady-state conditions. The measurements of carbon monoxide, carbon dioxide, and nitric oxide are based on continuous sampling and analysis by nondispersive infrared (NDIR) methods. Measurements of total oxides of nitrogen by chemiluminescence and NDIR methods is discussed.

The methods presented in this SAE Recommended Practice apply to the controlled testing of low-temperature charge, air-cooled, heavy-duty diesel engines. This document encompasses the following main sections: a Definitions of pertinent parameters b Vehicle testing to determine typical values for these parameters c Description of the setup and operation of the test cell system d Validation testing of the test cell system While not covered in this document, computer modeling of the vehicle engine cooler system is recognized as a valid tool to determine cooler system performance and could be utilized to supplement the testing described. However, adequate in-vehicle testing should be performed to validate the model before it is used for the purposes outlined. The procedure makes references to test cycles that are prescribed by the United States Environmental Protection Agency (US EPA) and are contained in the Code of Federal Regulations.