# 40 CFR Part 86, Appendix IX to Part 86 - Experimentally Determining the R-Factor for Bench Aging Durability Procedures

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View PDF at GPO Pt. 86, App. IX
Appendix IX to Part 86—Experimentally Determining the R-Factor for Bench Aging Durability Procedures
The R-Factor is the catalyst thermal reactivity coefficient used in the bench aging time (BAT) equation [Ref. § 86.1826-08(d)(3)]. Manufacturers may determine the value of R experimentally using the following procedures.
1. Using the applicable bench cycle and aging bench hardware, age several catalysts (minimum of 3 of the same catalyst design) at different control temperatures between the normal operating temperature and the damage limit temperature. Measure emissions (or catalyst inefficiency (1-catalyst efficiency)) for each constituent. Assure that the final testing yields data between one- and two-times the standard.
2. Estimate the value of R and calculate the effective reference temperature (Tr) for the bench aging cycle for each control temperature according to the procedure described in § 86.1826-08(d)(4).
3. Plot emissions (or catalyst inefficiency) versus aging time for each catalyst. Calculate the least-squared best-fit line through the data. For the data set to be useful for this purpose the data should have an approximately common intercept between 0 and 4000 miles. See the following graph for an example.
4. Calculate the slope of the best-fit line for each aging temperature.
5. Plot the natural log (ln) of the slope of each best-fit line (determined in step 4) along the vertical axis, versus the inverse of aging temperature (1/(aging temperature, deg K)) along the horizontal axis, Calculate the least-squared best-fit lines through the data. The slope of the line is the R-factor. See the following graph for an example.
6. Compare the R-factor to the initial value that was used in Step 2. If the calculated R-factor differs from the initial value by more than 5%, choose a new R-factor that is between the initial and calculated values, then repeat Steps 2-6 to derive a new R-factor. Repeat this process until the calculated R-factor is within 5% of the initially assumed R-factor.
7. Compare the R-factor determined separately for each constituent. Use the lowest R-factor (worst case) for the BAT equation.
[71 FR 2837, Jan. 17, 2006]

Title 40 published on 2014-07-01

The following are only the Rules published in the Federal Register after the published date of Title 40.

For a complete list of all Rules, Proposed Rules, and Notices view the Rulemaking tab.

• 2014-08-08; vol. 79 # 153 - Friday, August 8, 2014
1. 79 FR 46356 - Emergency Vehicle Rule—SCR Maintenance and Regulatory Flexibility for Nonroad Equipment
GPO FDSys XML | Text
ENVIRONMENTAL PROTECTION AGENCY
Final rule.
This rule is effective on September 8, 2014.
40 CFR Parts 86 and 1039

Title 40 published on 2014-07-01

The following are ALL rules, proposed rules, and notices (chronologically) published in the Federal Register relating to 40 CFR 86 after this date.

• 2014-08-08; vol. 79 # 153 - Friday, August 8, 2014
1. 79 FR 46356 - Emergency Vehicle Rule—SCR Maintenance and Regulatory Flexibility for Nonroad Equipment
GPO FDSys XML | Text
ENVIRONMENTAL PROTECTION AGENCY
Final rule.
This rule is effective on September 8, 2014.
40 CFR Parts 86 and 1039