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Vehicle and Fuel Emissions Testing

Emissions Testing Technical Resources at the National Vehicle and Fuel Emissions Laboratory (NVFEL)

This page provides detailed technical information on the emissions test methods, analysis, and calculations performed at the laboratory. The files on this page are often requested by various members of the emissions testing community and can help clarify, but not replace, official regulatory guidance and practices.

This graphic shows dilution of vehicle exhaust and the flow of emission samples through analytical instrumentation.Vehicle Emissions Sampling and Analysis (Click image to see larger.)

The Code of Federal Regulations is the official source of vehicle/engine certification test procedures.

Emissions Sampling and Analysis

This graphic shows dilution of vehicle exhaust and the flow of emission samples through analytical instrumentation.

Natural Gas Fuel Analysis

This worksheet follows ASTM procedures for the derivation of heating value and specific gravity from a report of the mole constituents of natural gas. EPA 40 CFR Parts 86 and 600 required values are also derived. Natural Gas Fuel Properties Derivation (XLS)(3 pp, 105 K) Free Viewers

Sample Emission and Fuel Economy Calculations

NOx Humidity Correction Factor