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Testing and Measuring Emissions

National Vehicle and Fuel Emissions Laboratory (NVFEL) Emissions Analysis

Please Note: 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. Vehicle Emissions Sampling and Analysis  (JPG, 163K)
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, 121K)

You will need Adobe Acrobat Reader to view the Adobe PDF files on this page. See EPA's PDF page for more information about getting and using the free Acrobat Reader.

Sample Emission and Fuel Economy Calculations
Natural Gas FTP Emissions Derivation (PDF) (12 pp, 137K)
Natural Gas Highway Emissions Derivation (PDF) (6 pp, 55K)
Natural Gas Fuel Economy Derivation (PDF) (2 pp, 30K)
NOx Humidity Correction Factor
Humidity and NOx Humidity Correction Factor Derivation (PDF) (11 pp, 161K)

For further information or assistance regarding this web page, please contact Bill Courtois, phone: (734) 214-4352 or email: courtois.william@epa.gov.

This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
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