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Emission Standards

China: Nonroad Diesel Engines

Regulatory Background

China’s emission requirements for diesel mobile nonroad engines have been progressively tightened from Stage I through Stage IV standards. Some of the important regulatory steps include:

  • 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. 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.
  • Stage III standards: In 2014.05, the MEP published GB 20891-2014 specifying China Stage III emission standards and proposed limits for Stage IV [3053] that were based on the EU Stage IIIA and EU Stage IIIB requirements, respectively. Limits for the smallest and largest engines were 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.
  • Stage IV standards: The proposed limits for Stage IV included in GB20891-2014 were supplemented with a 2018 proposal that included a PN limit and 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 but changed several times. The final Stage IV technical requirements (HJ 1014-2020) for machinery and engines rated 560 kW or less were issued 2020.12 with implementation starting 2022.12. In-service conformity (ISC) testing is required for most engine categories. For machinery and engines rated over 560 kW, final requirements were not included in HJ 1014-2020 and will be announced separately [3962][4135][4914][5030][5029].
  • Smoke emissions: In 2018.09, a test procedure and limits for measuring smoke emissions from nonroad equipment and vehicles, GB 36886-2018, was published. The procedure became effective in 2018.12.

Stage I/II Emission Standards

The standards, Table 1, were based on European regulations. The compliance dates were:

  • Stage I standards: 2007.10
  • Stage II standards: 2009.10
Table 1
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 Emission Standards

The final Stage III limits in GB20891-2014 are summarized Table 2. Limits for engines between 37 and 560 kW were based on EU Stage IIIA standards. Limits for engines above 560 kW and under 37 kW were based on US Tier 2 requirements. Stage III engines were tested over the ISO 8178 cycle. Durability requirements for Stage III and Stage IV engines are shown in Table 3 [3965][3053].

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 2
Stage III emission limits
Table 3
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

The Stage IV requirements initially proposed in GB 20891-2014 were based on EU Stage IIIB standards but with the addition of requirements for engines with net power >560 kW and <37 kW based on US Tier 2 standards. A proposal issued 2018.02 added a DPF-forcing PN limit of 5×1012 #/kWh [3053][3965][3962][4914]. Final requirements for machinery and engines with a rated power 560 kW and less were issued 2020.12 [5030][5029]. The standard not only applies to diesel engines for non-road mobile machinery, but also included requirements for non-road diesel mobile machinery. While requirements for machinery and engines with a rated power more than 560 kW were included in the various Stage IV proposals, these were not included in the final requirements issued 2020.12 and will be announced at a later date.

The Stage IV limits are summarized in Table 4. Durability requirements are shown in Table 3.

Table 4
Stage IV emission limits
P>560*3.50.403.5, 0.67a0.10
* Proposed limits
a Applicable to mobile generator sets with Pmax > 900 kW diesel engines

In 2018, an implementation date of 2020.01 was proposed but was subsequently changed several times [3962][4135][4914]. The final technical details for machinery and diesel engines rated 560 kW or less require implementation of Stage IV requirements 2022.12. Technical details for Stage IV, HJ1014-2020, supplement GB20891-2014. 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 (5×1012 #/kWh) to apply to 37-560 kW engines (and these engines are 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 for engines with SCR aftertreatment;
  • 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 is to be used as the primary in-use compliance tool for machinery with a 37 kW or larger diesel. A conformity factor (CF) of 2.5 applies to the 90% work based window for CO and NOx (CO and HC+NOx for 37≤P<56);
  • NTE limits of 2× those in Table 4 apply to gaseous emissions and PM for engines with electronically controlled fuel systems. PN is excluded from NTE requirements.
  • There is an OBD requirement for NOx and PM controls, covering EGR, DOC, DPF, SCR;
  • Telematics as well as global positioning will be required for all NRMMs equipped with Stage IV engines of 37-560 kW. Data that must be transmitted includes SCR inlet and outlet NOx and temperature, DPF pressure drop and DEF level.
  • CO2 emissions are to be reported. For machinery with engines of 37-560 kW, the fuel consumption is also to be reported.

In the 2018 draft proposal, manufacturers were encouraged to alternatively meet limits based on EU Stage V limits, Table 5 [3962].

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

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.