About GPO   |   Newsroom/Media   |   Congressional Relations   |   Inspector General   |   Careers   |   Contact   |   askGPO   |   Help  
Home   |   Customers   |   Vendors   |   Libraries  
The Code of Federal Regulations (CFR) annual edition is the codification of the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government produced by the Office of the Federal Register (OFR) and the Government Publishing Office.

Parallel Table of Authorities and Rules for the Code of Federal Regulations and the United States Code
Text | PDF

Find, review, and submit comments on Federal rules that are open for comment and published in the Federal Register using Regulations.gov.

Purchase individual CFR titles from the U.S. Government Online Bookstore.

Find issues of the CFR (including issues prior to 1996) at a local Federal depository library.


Electronic Code of Federal Regulations

e-CFR data is current as of May 1, 2015

Title 40Chapter ISubchapter CPart 90Subpart D → §90.304

Title 40: Protection of Environment
Subpart D—Emission Test Equipment Provisions

§90.304   Test equipment overview.

(a) All engines subject to this subpart are tested for exhaust emissions. Engines are operated on dynamometers meeting the specification given in §90.305.

(b) The exhaust is tested for gaseous emissions using a raw gas sampling system as described in §90.414 or a constant volume sampling (CVS) system as described in §90.421. Both systems require analyzers (see paragraph (c) of this section) specific to the pollutant being measured.

(c) Analyzers used are a non-dispersive infrared (NDIR) absorption type for carbon monoxide and carbon dioxide analysis; paramagnetic (PMD), zirconia (ZRDO), or electrochemical type (ECS) for oxygen analysis; a flame ionization (FID) or heated flame ionization (HFID) type for hydrocarbon analysis; and a chemiluminescent detector (CLD) or heated chemiluminescent detector (HCLD) for oxides of nitrogen analysis.

Need assistance?