Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:23:p11
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 23 (pt 11/15)
Character Range: 1927011–1930107

timing and engine speed controlled to achieve a minimum catalyst temperature of 800 °C                                3 % (±1 %)

              Figure C4 App1/2
              Standard Bench Cycle
              3. Ageing bench equipment and procedures
              3.1. Ageing bench configuration. The ageing bench shall provide the appropriate exhaust flow rate, temperature, air-fuel ratio, exhaust constituents and secondary air injection at the inlet face of the catalyst.
               The standard ageing bench consists of an engine, engine controller, and engine dynamometer. Other configurations may be acceptable (e.g. whole vehicle on a dynamometer, or a burner that provides the correct exhaust conditions), as long as the catalyst inlet conditions and control features specified in this appendix are met.
               A single ageing bench may have the exhaust flow split into several streams providing that each exhaust stream meets the requirements of this appendix. If the bench has more than one exhaust stream, multiple catalyst systems may be aged simultaneously.
              3.2. Exhaust system installation. The entire catalyst(s)-plus-oxygen and/or air fuel ratio sensor(s) system, together with all exhaust piping which connects these components, will be installed on the bench. For engines with multiple exhaust streams (such as some V6 and V8 engines), each bank of the exhaust system will be installed separately on the bench in parallel.

               For exhaust systems that contain multiple in-line catalysts, the entire catalyst system including all catalysts, all oxygen and/or air fuel ratio sensors and the associated exhaust piping will be installed as a unit for ageing. Alternatively, each individual catalyst may be separately aged for the appropriate period of time.
              3.3. Temperature measurement. Catalyst temperature shall be measured using a thermocouple placed in the catalyst bed at the location where the highest temperature occurs in the hottest catalyst. Alternatively, the feed gas temperature just before the catalyst inlet face may be measured and converted to catalyst bed temperature using a linear transform calculated from correlation data collected on the catalyst design and ageing bench to be used in the ageing process. The catalyst temperature shall be stored digitally at the speed of 1 Hz.

              3.4. Air/Fuel measurement. Provisions shall be made for the measurement of the air/fuel (A/F) ratio (such as a wide-range oxygen sensor) as close as possible to the catalyst inlet and outlet flanges. The information from these sensors shall be stored digitally at the speed of 1 Hz.

              3.5. Exhaust flow balance. Provisions shall be made to assure that the proper amount of exhaust (measured in grams/second at stoichiometry, with a tolerance of ±5 grams/second) flows through each catalyst system that is being aged on the bench.

               The proper flow rate is determined based upon the exhaust flow that would occur in the original vehicle's engine at the steady state engine speed and