[Code of Federal Regulations] [Title 40, Volume 30] [Revised as of July 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR1065.20] [Page 653] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 1065_TEST PROCEDURES AND EQUIPMENT--Table of Contents Subpart A_Applicability and General Provisions Sec. 1065.20 Limits for test conditions. (a) Unless specified elsewhere in this chapter, you may conduct tests to determine compliance with duty-cycle emission standards at ambient temperatures of 20-30[deg] C (68-86[deg] F), ambient pressures of 600-775 mm Hg, and any ambient humidity level. (b) Follow the standard-setting part for ambient conditions when testing to determine compliance with not-to-exceed or other off-cycle emission standards. (c) For engine testing in a laboratory, you may heat, cool, and/or dehumidify the dilution air before it enters the CVS. (d) For engine testing in a laboratory, if the barometric pressure observed while generating the maximum-torque curve changes by more than 25 mm Hg from the value measured when you started mapping, you must remap the engine. Also, to have a valid test, the average barometric pressure observed during the exhaust emission test must be within 25 mm Hg of the average observed during the maximum torque curve generation (see Sec. 1065.510).