(a) The purpose of the evaluation procedure specified in this section is to determine the effect of thermal stress on catalyst conversion efficiency for Phase 1 engines. The thermal stress is imposed on the test catalyst by exposing it to quiescent heated air in an oven. The evaluation of the effect of such stress on catalyst performance is based on the resultant degradation of the efficiency with which the conversions of specific pollutants are promoted. The application of this evaluation procedure involves the several steps that are described in the following paragraphs.
(b) Determination of initial conversion efficiency. (1) A synthetic exhaust gas mixture having the composition specified in Sec. 90.329 is heated to a temperature of 450 C [5 C and passed through the new test catalyst or, optionally, a test catalyst that has been exposed to temperatures less than or equal to 500 C for less than or equal to two hours, under flow conditions that are representative of anticipated in-use conditions.
(1) A synthetic exhaust gas mixture having the composition specified in Sec. 90.329 is heated to a temperature of 450 C [5 C and passed through the new test catalyst or, optionally, a test catalyst that has been exposed to temperatures less than or equal to 500 C for less than or equal to two hours, under flow conditions that are representative of anticipated in-use conditions.
(2) The concentration of each pollutant of interest, that is, hydrocarbons, carbon monoxide, or oxides of nitrogen, in the effluent of the catalyst is determined by means of the instrumentation that is specified for exhaust gas analysis in subpart D of this part.
(3) The conversion efficiency for each pollutant is determined by:
(i) Subtracting the effluent concentration from the initial concentration;
(ii) Dividing this result by the initial concentration; and
(iii) Multiplying this result by 100 percent.
(c) Imposition of thermal stress. (1) The catalyst is placed in an oven that has been pre-heated to 1000 C and the temperature of the air in the oven is maintained at 1000 C [10 C for six hours.
(1) The catalyst is placed in an oven that has been pre-heated to 1000 C and the temperature of the air in the oven is maintained at 1000 C [10 C for six hours.
(2) The catalyst is removed from the oven and allowed to cool to room temperature.
(d) Determination of final conversion efficiency. The steps listed in paragraph (b) of this section are repeated.
(e) Determination of conversion efficiency degradation. (1) The final conversion efficiency determined in paragraph (c) of this section is subtracted from the initial conversion efficiency determined in paragraph (b) of this section.
(1) The final conversion efficiency determined in paragraph (c) of this section is subtracted from the initial conversion efficiency determined in paragraph (b) of this section.
(2) This result is divided by the initial conversion efficiency.
(3) This result is multiplied by 100 percent.
(f) Determination of compliance with degradation limit. The percent degradation determined in paragraph (e) of this section must not be greater than 20 percent. [60 FR 34598, July 3, 1995, as amended at 64 FR 15244, Mar. 30, 1999]
Sec. Appendix A to Subpart E of Part 90--Tables
Table 1--Parameters to be Measured or Calculated and Recorded------------------------------------------------------------------------
Parameter Units------------------------------------------------------------------------Airflow rate (dry), if applicable................ g/hFuel flow rate................................... g/hEngine Speed..................................... rpmEngine Torque Output............................. N mPower Output..................................... kWAir inlet temperature............................ CAir humidity..................................... mg/kgCoolant temperature (liquid cooled).............. CExhaust mixing chamber surface temperature, if C
applicable.Exhaust sample line temperature, if applicable... CTotal Accumulated hours of Engine Operation...... hBarometric Pressure.............................. kPa------------------------------------------------------------------------
Table 2--Test Cycles for Class I-A, I-B, and Class I-V Engines--------------------------------------------------------------------------------------------------------------------------------------------------------
Mode Speed 1 2 3 4 5 6 7 8 9 10 11--------------------------------------------------------------------------------------------------------------------------------------------------------
Rated Speed
Intermediate Speed IdleMode Points--A Cycle................................. ....... ....... ....... ....... ....... 1 2 3 4 5 6Load Percent--A Cycle................................ ....... ....... ....... ....... ....... 100 75 50 25 10 0Weighting............................................ ....... ....... ....... ....... ....... 9% 20% 29% 30% 7% 5%Mode Points--B Cycle................................. 1 2 3 4 5 ....... ....... ....... ....... ....... 6Load Percent--B Cycle................................ 100 75 50 25 10 ....... ....... ....... ....... ....... 0Weighting............................................ 9% 20% 29% 30% 7% ....... ....... ....... ....... ....... 5%Mode Points--C Cycle................................. 1 ....... ....... ....... ....... ....... ....... ....... ....... ....... 2Load Percent--C Cycle................................ 100 ....... ....... ....... ....... ....... ....... ....... ....... ....... 0Weighting for Phase 1 Engines........................ 90% ....... ....... ....... ....... ....... ....... ....... ....... ....... 10%Weighting for Phase 2 Engines........................ 85% ....... ....... ....... ....... ....... ....... ....... ....... ....... 15%-------------------------------------------------------------------------------------------------------------------------------------------------------- [60 FR 34598, July 3, 1995, as amended at 65 FR 24313, Apr. 25, 2000]
Sec. Appendix B to Subpart E of Part 90--Figures
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