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Emission Standards

China: Nonroad Engines

Regulatory Background

The implementation of China’s emission standards for diesel and small spark ignition (SI) mobile nonroad engines is summarized in Table 1. Some of the important regulatory steps include:

  • Diesel Stage I/II standards: The first emission standards for mobile nonroad diesel engines (GB 20891-2007) were adopted in 2007 [2880]. The requirements were based on the European Stage I/II nonroad emission standards. However, the Chinese regulation also covered small diesel engines, which were not subject to the European standards. Emission limits for the smallest engines were consistent with US Tier 1/2 nonroad standards.
  • Diesel Stage III/IV standards: In May 2014, the MEP published GB 20891-2014 specifying China Stage III emission standards and proposed limits for Stage IV [3053] that are based on the EU Stage IIIA and EU Stage IIIB requirements, respectively. Limits for the smallest and largest engines are based on US Tier 2 requirements. The Stage III standards became effective from 2014.10 for new types and from 2015.10 for all engines. The proposed limits for Stage IV included in GB20891-2014 were further supplemented with a proposal issued in February 2018 with a wall flow DPF requirement. Engine makers were also encouraged to meet standards based on EU Stage V standards. A Stage IV implementation date of 2020.01 was proposed and later changed to 2020.12 [3962][4135].
  • Smoke emissions: In September 2018, a test procedure and limits for measuring smoke emissions from non-road equipment and vehicles, GB 36886-2018, was published. The procedure became effective in December 2018.
  • Small SI Stage I/II standards: In December 2010, emissions standards for mobile nonroad spark ignition engines < 19 kW were published (GB26133-2010), with limits based on EU and US standards. Stage I requirements became effective 2010.03. Stage II implementation was different for non-handheld/handheld engines with requirements for new engine types starting 2013.01/2015.01 respectively and all new engines 2014.01/2016.01 respectively [3963][3964].
Table 1
Implementation of national nonroad engine emission standards
Small SI; nHHIII

Diesel Engines

Stage I/II Emission Standards

The standards, Table 2, were based on European regulations. The compliance dates were:

  • Stage I standards: 2007.10
  • Stage II standards: 2009.10
Table 2
Stage I/II standards for nonroad diesel engines, g/kWh
Max Power (P), kWCOHCNOxHC+NOxPM
Stage I†
130 ≤ P ≤ 5605.01.39.2-0.54
75 ≤ P < 1305.01.39.2-0.7
37 ≤ P < 756.51.39.2-0.85
18 ≤ P < 378.42.110.8-1.0
8 ≤ P < 188.4--12.9-
0 < P < 812.3--18.4-
Stage II
130 ≤ P ≤ 5603.51.06.0-0.2
75 ≤ P < 1305.01.06.0-0.3
37 ≤ P < 755.01.37.0-0.4
18 ≤ P < 375.51.58.0-0.8
8 ≤ P < 186.6--9.50.8
0 < P < 88.0--10.51.0
† Stage I limits shall be achieved before any exhaust aftertreatment device.

Emissions were measured over a steady-state test cycle equivalent to the ISO 8178 C1, 8-mode test. Other ISO 8178 test cycles could be used for selected applications.

Stage III/IV Emission Standards

GB20891-2014 included the Stage III limits as well as proposed Stage IV limits, Table 3. The Stage III limits are based on EU Stage IIIA standards and the proposed Stage IV limits on EU Stage IIIB standards but with the addition of engines with net power >560 kW and < 37 kW. Limits for engines above 560 kW and under 37 kW are based on US Tier 2 requirements. Stage III engines and constant speed Stage IV engines are measured over the ISO 8178. Variable speed Stage IV engines were to be tested over the NRTC. Durability requirements are shown in Table 4 [3965].

The compliance dates for Stage III diesel engine standards were [3966]:

  • New engine types: 2014.10
  • All new engines: 2015.10
  • After 2016.04, all new non-road mobile machinery required a Stage III engine
  • After 2016.12, all new agricultural machinery required a Stage III engine
Table 3
Stage III and proposed Stage IV limits
Stage IIIP>5603.56.40.20
Proposed Stage IVP>5603.50.403.5, 0.67*0.10
* Applicable to mobile generator sets with Pmax > 900 kW diesel engines
Table 4
Stage III/IV durability requirements
Power, kWRated speed, rpmEffective life, hMinimum durability test duration, h
19≤P<37Variable speed50001250
Constant speed < 3000
Constant speed ≥ 30003000750

Stage IV Emission Standards—2018/19 Revisions

The Stage IV requirements proposed in GB 20891-2014, Table 3, were further clarified and supplemented with additional requirements through a proposal issued 2018.02. This proposal supplemented the Stage IV requirements in Table 3 with a DPF-forcing standard—a maximum PN limit of 5×1012 #/kWh. Engine manufacturers were also encouraged to instead meet limits based on EU Stage V limits, Table 5.

Table 5
Voluntary emission limits proposed in 2018
P>5603.50.193.5, 0.67*0.045
* Applicable to mobile generator sets with Pmax > 900 kW diesel engines

Initially, an implementation date of 2020.01 was proposed; all nonroad engines produced on or after this date would be required to meet the updated Stage IV requirements [3962]. A revision to the proposal published 2019.02 changed the implementation date to 2020.12, pointed to a supplemental document “Technical Requirements for Non-road Diesel Mobile Machinery Pollutant Emission Control” (HJ 1014) for additional compliance guidance and stated that proposed China Stage V limits will also be included in the final regulation [4135].

Additional details for Stage IV include:

  • Constant speed diesel engines would be tested over the NRSC and variable speed engines over the NRTC;
  • Wider applicable ambient boundary conditions;
  • PN limit to apply to 37-560 kW engines (engines to be equipped with a wall-flow DPF);
  • There should be no visible smoke during DPF regeneration;
  • Average ammonia emissions are not to exceed 25 ppm;
  • If the engine is equipped with a vanadium containing SCR catalyst, data demonstrating that vanadium emissions will not occur during the useful life is required and SCR inlet temperatures above 550°C are not allowed;
  • PEMS to be used as the primary in-use compliance tool;
  • An OBD requirement for NOx and PM controls, covering EGR, DOC, DPF, SCR;
  • Global positioning system will be required for all NRMMs equipped with engines of 37-560 kW.

In-use Smoke Emissions

In the September 2018, Limits and measurement methods for exhaust smoke from non-road mobile machinery equipped with diesel engine, GB 36886-2018, was published [4023]. This standard specifies the exhaust smoke limit and measurement method for on-site measurements of non-road diesel mobile machinery and vehicles as well as new and imported equipment. It covers non-road diesel fueled vehicles and machinery equipped with variable as well as constant speed engines. Smoke measurements can be carried out with an opacity meter according to GB 3847 [4022] or using the Ringelmann method as described in an appendix to GB 36886-2018. The corresponding limits are summarized in Table 6.

Table 6
Exhaust smoke limits
CategoryRated net power, PmaxLight absorption coefficientaRingelmann Blackness
Class IPmax < 193.001
19 ≤ Pmax < 372.00
37 ≤ Pmax ≤ 5601.61
Class IIPmax < 192.001
19 ≤ Pmax < 371.001 (no visible smoke)
Pmax ≥ 370.80
Class IIIPmax < 370.801 (no visible smoke)
Pmax ≥ 370.50
a for engines operating above 1700 m, the limit can be increased by 0.25 1/m

Class I limits apply to machinery with Stage I and II diesel engines (GB 20891-2007) and Class II limits to machinery with Stage III and subsequent diesel engines (GB 20891-2014). Class III limits can be used to limit emissions in low emission zones defined by the government.

On-site smoke measurements are carried out during the normal usage cycle of the equipment. If this is not possible, the free acceleration method (GB 3847) can be used. Opacity meter measurements are carried out with a sampling frequency no less than 1 Hz and the maximum reading is taken as the test result. Ringelmann readings can be taken by video or other similar method with the maximum Ringelmann rating taken as the test result.

Small SI Engines

Stage I/II Emission Standards

Stage I and II emissions requirements for small nonroad spark ignition engines are found in GB26133-2010 [3967]. This standard applies to (but is not limited to) spark ignition engines with a net power of no more than 19 kW for use in nonroad mobile machinery such as: lawn mowers, chain saws, generators, water pumps and brush cutters. Engines with a net power greater than 19 kW but a working volume of no more than 1 L may be certified as well. It does not apply to engines for the following purposes: for driving boats; for underground mining or underground mining equipment; for emergency rescue equipment; for recreational vehicles such as sleds, motocross and all-terrain vehicles; engines built for export.

The application dates are as follows:

  • Stage I: New types/all new non-handheld and hand-held engines 2011.03/2012.03, respectively.
  • Stage II:
    • New types/all new non-handheld engines 2013.01/2014.01.
    • New types/all new hand-held engines 2015.01/2016.01, respectively.

Testing is in accordance with ISO 8178 (GB/T 8190.4). Emission requirements are based on EU Directive 97/68/EC and its amendments found in 2002/88/EC as well as US EPA Phase 1 and 2 regulations (40 CFR Part 90).

Engines are classified according to displacement volume as shown in Table 7.

Table 7
Small SI engine classification
Engine classificationDisplacement Volume, cm3

Stage 1 limits are shown in Table 8 and Stage 2 limits in Table 9. The durability requirements are shown in Table 10. Two-stroke engines for snow blowers, whether or not they are hand-held, only need to meet the SH1, SH2 or SH3 of the corresponding working volume. For natural gas-fueled engines, NMHC may be used instead of HC.

Table 8
Small SI engine Stage I emission limits, g/kWh
Engine classificationCOHCNOxHC+NOx
Table 9
Small SI engine Stage II emission limits, g/kWh
Engine classificationCONOxHC+NOx
Table 10
Durability requirements for small SI engines, hrs
Engine classificationDurability class