All EPA approvals are specific not only to a given test method and laboratory, but also to a particular version of that test method. Thus, if ASTM or ISO released a revised version of a test method, any EPA approvals for previous versions of that same test method would remain valid and laboratories could continue to use the previous version.

If the laboratory intended to use the revised version of the test method, formal approval must be sought from EPA. EPA is exploring procedures in the context of the current regulations under which a revision to a specific test method could be deemed inconsequential to its accuracy and precision. If such a procedure can be developed, EPA may be able to permit the qualification for the old version of a test method to apply also to the new version of that test method.

Question and Answer was originally posted at Questions and Answers on the Clean Diesel Fuel Rules (PDF)(135 pp, 888 K, EPA420-B-06-010, July 2006, About PDF)