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非路移柴油发动机
Off-Highway Motorcycles
Small Engines ATVs Utility Vehicles Diesel Non-Road

Nonroad Diesel Engines

Summary of EPA Regulations
Certification Process
Emission Standards for Nonroad Diesel Engines
Averaging, Banking, and Trading for Certification
Emission Warranty Requirements
Importer Responsibilities
More Information

Introduction

This web page provides a summary of the United States environmental regulations for nonroad diesel engines used in equipment such as farm tractors, bulldozers, and portable generators. The information is provided for foreign manufacturers and importers who want to import equipment containing these engines into the United States. The full set of regulations for nonroad diesel engines can be found at 40 CFR 1039.

The United States is very concerned about air pollution because of the health effects it causes.  This includes respiratory problems, heart disease and cancer.  The U.S. Environmental Protection Agency (EPA) is responsible for writing regulations that limit the amount of air pollution from various sources, including small engines. 

Summary of EPA Regulations

EPA has developed a comprehensive program to reduce emissions from future nonroad diesel engines by:

  • Establishing engine emission standards. To meet the emission standards, engine manufacturers must produce new engines with advanced emission-control technologies similar to those already expected for highway trucks and buses. Exhaust emissions from these new diesel engines will be 90 percent cleaner than older engines.
  • Limiting the amount of sulfur in nonroad diesel fuels. Because advanced emission-control devices can be damaged by sulfur, EPA requires a reduction in the allowable level of sulfur in nonroad diesel fuel by more than 99 percent.

Diesel engine emissions regulations have been phased in starting in 1996:

  • Tier 1-3 Standards. The 1998 nonroad engine regulations are structured as a 3-tiered progression. Each tier involves a phase in (by horsepower rating) over several years. Tier 1 standards were phased-in from 1996 to 2000. The more stringent Tier 2 standards took effect from 2001 to 2006, and yet more stringent Tier 3 standards phased-in from 2006 to 2008 (Tier 3 standards apply only for engines from 37-560 kW). Tier 1-3 standards are met through advanced engine design, with no or only limited use of exhaust gas aftertreatment (oxidation catalysts).
  • Tier 4 Standards. The Tier 4 standards require that emissions of PM and NOx be further reduced by about 90%. Such emission reductions can be achieved through the use of control technologies—including advanced exhaust gas aftertreatment—similar to those required by the 2007-2010 standards for highway engines.

Nonroad diesel fuel regulations are also being phased in. At the Tier 1-3 stage, the sulfur content in nonroad diesel fuels was not limited by environmental regulations. The oil industry specification was 0.5% (wt., max), with the average in-use sulfur level of about 0.3%. To enable sulfur-sensitive control technologies in Tier 4 engines—such as catalytic particulate filters and NOx adsorbers—the EPA mandated reductions in sulfur content in nonroad diesel fuels, as follows:

  • 500 ppm effective June 2007 for nonroad, locomotive and marine (NRLM) diesel fuels
  • 15 ppm (ultra-low sulfur diesel) effective June 2010 for nonroad fuel, and June 2012 for locomotive and marine fuels

For more information of diesel fuel programs and regulations see Fuels and Fuel Additives.

Certification Process

To import nonroad diesel engines into the U.S., the manufacturer must implement a series of steps to demonstrate that the engines meet EPA air pollution standards. This process includes the following steps:

  • Divide your nonroad diesel product line into families of engines that are expected to have similar emission characteristics. (For more information on selecting engine families see 40 CFR 1039.230.)
  • Obtain a certificate of conformity for each engine family by testing engine emissions and submitting an application to EPA.  The test data must show that the engines meet EPA air pollution standards for the useful life of the vehicles. You may use averaging and banking provisions to show compliance as described later in the section. Ordinarily, the manufacturer, not the importer, obtains EPA certification for imported nonroad diesel engines. However, an importer also may apply to EPA for a certificate, on the condition that the importer assumes all the responsibilities of the manufacturer. (For more information on obtaining a certificate of conformity see 40 CFR 1039.201.)
  • Label each nonroad diesel engine with a vehicle identification number, an emission control label and other specified information.  If an engine is not labeled, the engine is presumed by U.S government agencies to be uncertified. Therefore, the engine may not be imported into the U.S. (For more information on labeling see 40 CFR 1039.135.)
  • Maintain records including your application, engineering data and results of emission control tests.  Provide records to EPA, if requested.  (For more information on record keeping see 40 CFR 1039.735.)
  • Complete EPA Form 3520-21.  This form must be prepared by the importer for each imported nonroad diesel engine.

Emission Standards for Nonroad Diesel Engines

Emission standards for non-road diesel engines for model years 2014 and earlier. The emission standards for non-road diesel engines for model years 2014 and earlier are shown in Tables 1 through 8.

TABLE 1 OF § 1039.102—TIER 4 EXHAUST EMISSION STANDARDS
(g/kW-HR): kW < 19
Maximum engine power
Model years
PM
NOX + NMHC
CO
kW < 8
2008–2014
10.40
7.5
8.0
8 ≤ kW < 19
2008–2014
0.40
7.5
6.6

1 For engines that qualify for the special provisions in § 1039.101(c), you may delay certifying to the standards in this part 1039 until 2010. In 2009 and earlier model years, these engines must instead meet the applicable Tier 2 standards and other requirements from 40 CFR part 89. Starting in 2010, these engines must meet a PM standard of 0.60 g/kW-hr, as described in § 1039.101(c). Engines certified to the 0.60 g/kWhr PM standard may not generate ABT credits.

 

TABLE 2 OF § 1039.102—TIER 4 EXHAUST EMISSION STANDARDS
(g/kW-HR): 19 > kW < 37
Model years
PM
NOX + NMHC
CO
2008–2012
0.30
7.5
5.5
2013–2014
0.03
4.7
5.5

 

TABLE 3 OF § 1039.102—TIER 4 EXHAUST EMISSION STANDARDS
(g/kW-HR): 37 > kW < 56
Option1
Model years
PM
NOX + NMHC
CO
#1
2008–2012
0.30
4.7
5.0
#2
2012
0.03
4.7
5.0
All
2013–2014
0.30
4.7
5.0

1You may certify engines to the Option #1 or Option #2 standards starting in the listed model year. Under Option #1, all engines at or above 37 kW and below 56 kW produced before the 2013 model year must meet the applicable Option #1 standards in this table. These engines are considered to be ‘‘Option #1 engines.’’ Under Option #2, all these engines produced before the 2012 model year must meet the applicable standards under 40 CFR part 89. Engines certified to the Option #2 standards in model year 2012 are considered to be ‘‘Option #2 engines.’’

 

TABLE 4 OF § 1039.102—TIER 4 EXHAUST EMISSION STANDARDS
(g/kW-HR): 56 > kW < 75
Model years1
Phase-in Option
PM
NOX
NMHC
NOX + NMHC
CO
 
Phase-in
0.02
0.40
0.19
5.0
2012–2013
Phase-out
0.02
4.7
5.0
2014
All Engines
0.02
0.40
0.19
5.0

1See paragraph (d)(2) of this section for provisions that allow for a different phase-in schedule than that specified in paragraph (c)(1) of this section.

 

TABLE 5 OF § 1039.102—TIER 4 EXHAUST EMISSION STANDARDS
(g/kW-HR): 75 > kW < 130
Model years1
Phase-in Option
PM
NOX
NMHC
NOX + NMHC
CO
 
Phase-in
0.02
0.40
0.19
5.0
2012–2013
Phase-out
0.02
4.0
5.0
2014
All Engines
0.02
0.40
0.19
5.0

1See paragraph (d)(2) of this section for provisions that allow for a different phase-in schedule than that specified in paragraph (c)(1) of this section.

 

TABLE 6 OF § 1039.102—TIER 4 EXHAUST EMISSION STANDARDS
(g/kW-HR): 130 > kW < 560
Model years
Phase-in Option
PM
NOX
NMHC
NOX + NMHC
CO
 
Phase-in
0.02
0.40
0.19
3.5
2011–2013
Phase-out
0.02
4.0
3.5
2014
All Engines
0.02
0.40
0.19
3.5

 

TABLE 7 OF § 1039.102—TIER 4 EXHAUST EMISSION STANDARDS
(g/kW-HR): kW > 560
Model years
Maximum Engine Power
Application
PM
NOX
NMHC
CO
 
560 < kW ≤ 900
All
0.10
3.5
0.40
3.5
 
Generator sets
0.10
0.67
0.40
3.5
2011–2014
kW > 900
All except generator sets.
0.10
3.5
0.40
3.5

 

TABLE 8 OF § 1039.102—INTERIM TIER 4 FEL Caps, g/kW-HR
Maximum engine power
Phase-in option
Model years1
PM
NOX
NOX + NMHC
kW < 19
2008–2014
0.80
29.5
19 ≤ kW < 37
2008–2012
0.60
9.5
37 ≤ kW < 56
32008–2012
0.40
7.5
56 ≤ kW < 130
Phase-in
2012–2013
0.04
0.80

56 ≤ kW < 130
Phase-out
2012–2013
0.04
46.6
130 ≤ kW ≤ 560
Phase-in
2011–2013
0.04
0.80
130 ≤ kW ≤ 560
Phase-out
2011–2013
0.04
56.4
kW < 560

1 For model years before 2015 where this table does not specify FEL caps, apply the FEL caps shown in
§ 1039.101.
2 For engines below 8 kW, the FEL cap is 10.5 g/kW-hr for NOX+NMHC emissions.
3 For manufacturers certifying engines to the standards of this part 1039 in 2012 under Option #2 of Table 3 of § 1039.102, the FEL caps of § 1039.101 apply for model year 2012 and later; see 40 CFR part 89 for provisions that apply to earlier model years.
4 For engines below 75 kW, the FEL cap is 7.5 g/kW-hr for NOX+NMHC emissions.
5 For engines below 225 kW, the FEL cap is 6.6 g/kW-hr for NOX+NMHC emissions.

For more information on emission standards for non-road diesel engines for model years 2014 and earlier see 40 CFR 1039.102.

Emission standards for non-road diesel engines after model year 2014. The emission standards for non-road diesel engines after model year 2014 are shown in Tables 1 through 4.

TABLE 1 OF § 1039.101—TIER 4 EXHAUST EMISSION STANDARDS AFTER THE 2014 MODEL YEAR, g/kW-HR1
Maximum engine power
Application
PM
NOX
NMHC
NOX + NMHC
CO
kW < 19
All
20.40
7.5
36.6
19 ≤ kW < 56
All
0.03
4.7
45.0

56 ≤ kW <130

All
0.02
0.40
0.19
5.0
130 ≤ kW ≤ 560
All
0.02
0.40
0.19
3.5
Generator sets
0.03
0.67
0.19
3.5
kW > 560
All except generator sets
0.04
3.5
0.19
3.5

1 Note that some of these standards also apply for 2014 and earlier model years. This table presents the full set of emission standards that apply after all the transition and phase-in provisions of § 1039.102 expire.
2 See paragraph (c) of this section for provisions related to an optional PM standard for certain engines below 8 kW.
3 The CO standard is 8.0 g/kW-hr for engines below 8 kW.
4 The CO standard is 5.5 g/kW-hr for engines below 37 kW.

 

TABLE 2 OF § 1039.101—TIER 4 FEL CAPS AFTER THE 2014 MODEL YEAR, g/kW-HR
Maximum engine power
Application
PM
NOX
NOX + NMHC
kW < 19
All
0.80
19.5
19 ≤ kW < 56
All
0.05
7.5

56 ≤ kW <130

All
0.04
0.80
130 ≤ kW ≤ 560
All
0.04
0.80
kW > 560
Generator sets
0.05
1.07
All except generator sets
0.07
6.2

1 For engines below 8 kW, the FEL cap is 10.5 g/kW-hr for NOX+NMHC emissions.

 

TABLE 3 OF § 1039.101—ALTERNATE FEL CAPS, g/kW-HR
Maximum engine power
Starting model year1
PM FEL cap
NOX FEL cap
19 ≤ kW < 56
22016
0.30

56 ≤ kW <130

2016
30.30
3.8
130 ≤ kW ≤ 560
2015
0.20
3.8
kW > 560
2019
0.10
43.5

1 See § 1039.104(g) for alternate FEL caps that apply in earlier model years.
2 For manufacturers certifying engines under Option #1 of Table 3 of § 1039.102, these alternate FEL caps apply starting with the 2017 model year.
3 For engines below 75 kW, the FEL caps are 0.40 g/kW-hr for PM emissions and 4.4 g/kW-hr for NOX emissions.
4 For engines above 560 kW, the provision for alternate NOX FEL caps is limited to generator-set engines. For example, if you produce 1,000 generator-set engines above 560 kW in a given model year, up to 50 of them may be certified to the alternate NOX FEL caps.

 

TABLE 4 OF § 1039.101—USEFUL LIFE VALUES
If your engine is certified as ...
And its maximum power is ...
And its rated speed is ...
Then its useful life is ...
(i) Variable speed or constant speed.
kW < 19
Any speed
3,000 hours or five years, whichever comes first.
(ii) Constant speed
19 ≤ kW < 37
3,000 rpm or higher
3,000 hours or five years, whichever comes first.
(iii) Constant speed
19 ≤ kW < 37
Less than 3,000 rpm
5,000 hours or seven years, whichever comes first.
(iv) Variable
19 ≤ kW < 37
Any speed
5,000 hours or seven years, whichever comes first.
(v) Variable speed or constant speed
kW ≥ 37
Any speed
8,000 hours or ten years, whichever comes first.

For more information on emission standards for non-road diesel engines after model year 2014 see 40 CFR 1039.101.

Smoke standards. Smoke from nonroad diesel engines may not exceed the following standards:

  • 20 percent during the acceleration mode.
  • 15 percent during the lugging mode.
  • 50 percent during the peaks in either the acceleration or lugging modes.

For more information on smoke standards see 40 CFR 1039.105.

Averaging, Banking, and Trading for Certification

To give manufacturers flexibility in meeting the standards for nonroad diesel engines, EPA allows averaging, banking and trading:

  • Averaging applies only to manufacturers that make more than one engine family. Averaging allows a manufacturer to certify engine families based on the average emissions over all of the manufacturer’s families, in a given model year. Thus if one or more engine families are above the applicable emission standard but another engine family is certified below the same emission standard, and if the emissions averaged over all of the manufacturer’s families are at or below the level of the emission standard, the manufacturer can certify all of the families. (For more information on averaging see 40 CFR 1039.710.)
  • Banking allows an engine manufacturer to retain credits for one model year, and use them for averaging or trading in a future model year. (For more information on banking see 40 CFR 1039.715.)
  • Trading allows different engine manufacturers to exchange of emission credits among themselves. The credits can then be used for averaging purposes, banked for future use, or traded to another engine manufacturer. (For more information on trading see 40 CFR 1039.720.)

Emission Warranty Requirements

You must warranty your emission control system must for up to 3,000 hours or five years (1,500 hours/two years for smaller engines running at lower speeds), whichever comes first. You must warrant to the ultimate purchaser and each subsequent purchaser that the new engine, including all parts of its emission-control system, meets two conditions:

  • It is designed, built, and equipped so it conforms at the time of sale to the ultimate purchaser with the requirements of this part.
  • It is free from defects in materials and workmanship that may keep it from meeting these requirements.

This warranty is separate and apart from any other manufacturer warranty. For more information on warranty requirements see 40 CFR 1039.120.

Importer Responsibilities

Along with the manufacturer the importer is responsible for ensuring that nonroad diesel engines imported to the United States comply with all certification standards and requirements:

  • Importers are prohibited from importing engines that are not EPA-certified and labeled.  (EPA highly recommends that importers inspect the engines they intend to import to verify that they are EPA-certified and labeled.)  
  • Importers are responsible for ensuring that the engine manufacturer will honor the emissions warranty.
  • The importer bears responsibility for any requirements not met by the original engine manufacturer.
  • The importer must complete EPA Declaration Form 3520-21, which requires confirmation of EPA certification or a description of the applicable exemption. Form 3520-21 must be submitted to CBP upon request along with other CBP entry documents.

For more information on importing see: http://epa.gov/otaq/imports/index.htm

More Information

EPA summary of regulations and standards for diesel engines.

Importing Vehicles and Engines. An EPA web page that provides various resources.

Control of Emissions from Recreational Engines and Vehicles (40 CFR 1051). The full test of the regulations for control of emissions from recreational vehicles, including off-highway motorcycles.

Final Regulatory Support Document: Control of Emissions from Unregulated Nonroad Engines (PDF) (September 2002).

Engine emission testing requirements and procedures: 40 CFR 1039.235 and 40 CFR Part 1065.

EPA Form 3520-21.  This form must be prepared by the importer for each imported nonroad or heavy-duty engine. This form can be filled out electronically, except for the signature, using Adobe Acrobat Reader. Also, highlighted regulatory cites in the form are linked directly to the daily online CFR.

Enforcement Alert: EPA Enforcing Stringent Standards for All Nonroad Engines (Sept. 2006). A useful compliance assistance resource that contains information on applicable enforcement actions regarding small engines.