[Code of Federal Regulations] [Title 40, Volume 18] [Revised as of July 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR91.305] [Page 318-319] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 91--CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES--Table of Contents Subpart D--Emission Test Equipment Provisions Sec. 91.305 Dynamometer specifications and calibration accuracy. (a) Dynamometer specifications. (1) The dynamometer test stand and other instruments for measurement of engine speed and torque must meet the accuracy requirements shown in Table 2 in appendix A to this subpart. The dynamometer must be capable of performing the test cycle described in Sec. 91.410. (b) Dynamometer calibration accuracy. (1) The dynamometer test stand and other instruments for measurement of engine torque and speed must meet the calibration frequency shown in Table 2 in appendix to this subpart. [[Page 319]] (2) A minimum of three calibration weights for each range used is required. The weights must be equally spaced and traceable to within 0.5 percent of National Institute of Standards and Testing (NIST) weights. Laboratories located in foreign countries may certify calibration weights to local government bureau standards.