[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: 40CFR1039.525]

[Page 503-504]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1039_CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD 
COMPRESSION-IGNITION ENGINES--Table of Contents
 
                        Subpart F_Test Procedures
 
Sec. 1039.525  How do I adjust emission levels to account for infrequently 
regenerating aftertreatment devices?

    This section describes how to adjust emission results from engines 
using aftertreatment technology with infrequent regeneration events. For 
this section, ``regeneration'' means an intended event during which 
emission levels change while the system restores aftertreatment 
performance. For example, exhaust gas temperatures may increase 
temporarily to remove sulfur from adsorbers or to oxidize accumulated 
particulate matter in a trap. For this section, ``infrequent'' refers to 
regeneration events that are expected to occur on average less than once 
over the applicable transient duty cycle or ramped-modal cycle, or on 
average less than once per typical mode in a discrete-mode test.
    (a) Developing adjustment factors. Develop an upward adjustment 
factor and a downward adjustment factor for each pollutant based on 
measured emission data and observed regeneration frequency. Adjustment 
factors should generally apply to an entire engine family, but you may 
develop separate adjustment factors for different engine configurations 
within an engine family. If you use adjustment factors for 
certification, you must identify the frequency factor, F, from paragraph 
(b) of this section in your application for certification and use the 
adjustment factors in all testing for that engine family. You may use 
carryover or carry-across data to establish adjustment factors for an 
engine family, as described in Sec. 1039.235(d), consistent with good 
engineering judgment. All adjustment factors for regeneration are 
additive. Determine adjustment factors separately for different test 
segments. For example, determine separate adjustment factors for hot-
start and cold-start test segments and for different modes of a 
discrete-mode steady-state test. You may use either of the following 
different approaches for engines that use aftertreatment with infrequent 
regeneration events:
    (1) You may disregard this section if regeneration does not 
significantly affect emission levels for an engine family (or 
configuration) or if it is not practical to identify when regeneration 
occurs. If you do not use adjustment factors under this section, your 
engines must meet emission standards for all testing, without regard to 
regeneration.
    (2) If your engines use aftertreatment technology with extremely 
infrequent regeneration and you are unable to apply the provisions of 
this section, you may ask us to approve an alternate methodology to 
account for regeneration events.
    (b) Calculating average adjustment factors. Calculate the average 
adjustment factor (EFA) based on the following equation:

EFA = (F)(EFH) + (1-F)(EFL)

Where:
F = the frequency of the regeneration event in terms of the fraction of 
          tests during which the regeneration occurs.
EFH = measured emissions from a test segment in which the 
          regeneration occurs.
EFL = measured emissions from a test segment in which the 
          regeneration does not occur.

    (c) Applying adjustment factors. Apply adjustment factors based on 
whether regeneration occurs during the test run. You must be able to 
identify regeneration in a way that is readily apparent during all 
testing.
    (1) If regeneration does not occur during a test segment, add an 
upward adjustment factor to the measured emission rate. Determine the 
upward adjustment factor (UAF) using the following equation:

UAF = EFA - EFL

    (2) If regeneration occurs or starts to occur during a test segment, 
subtract a downward adjustment factor from the measured emission rate. 
Determine the downward adjustment factor (DAF) using the following 
equation:

DAF = EFH - EFA

    (d) Sample calculation. If EFL is 0.10 g/kW-hr, 
EFH is 0.50 g/kW-hr, and F is 0.1 (the regeneration occurs 
once for each ten tests), then:


[[Page 504]]


EFA = (0.1)(0.5 g/kW-hr) + (1.0 - 0.1)(0.1 g/kW-hr) = 0.14 g/
          kW-hr.
UAF = 0.14 g/kW-hr - 0.10 g/kW-hr = 0.04 g/kW-hr.
DAF = 0.50 g/kW-hr - 0.14 g/kW-hr = 0.36 g/kW-hr.