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Emission Standards

China: Nonroad Engines: ISC Testing

For China Stage IV engines, in-service conformity (ISC) requirements were included in the supplemental requirements (HJ 1014-2020) published in 2020 [5030][5029]. Application commences with the Stage IV implementation date of 2022.12 and requires ISC of gaseous emissions from Stage IV engines from 37 to 560 kW. CO and NOx emissions must meet Stage IV limits multiplied by a conformity factor (CF).

While the process is based on the EU in-service monitoring (ISM) requirements, some differences exist. Selected requirements and differences with the EU program are summarized in Table 1.

Table 1
Comparison of China Stage IV and Euro Stage V ISM requirements
ParameterChina Stage IVEU Stage V
Temperature, min.-10°C-7°C
Temperature, max.38°C-0.4514·(101.3-pb) + 311 K
where pb is the ambient pressure, kPa
Altitude max.1700 mAmbient pressure ≥ 82.5 kPa
Start of evaluationCoolant > 70°C or coolant stable ±2 K for 5 minutes. No later than 20 minutes after engine start
DPF regeneration correction DPF regeneration is not allowed but emissions are corrected by a Ki factor reflecting the effect of periodic regeneration.Not mentioned
When testing is carried out After 500 h of operation, within effective lifetime. For new machinery discharge compliance inspection, up to 5 h operation is allowed. 56≤P<130 kW: before 20% of EDP and after 55% of EDP
130≤P<560 kW: before 30% of EDP and after 70% of EDP
PollutantsCO, CO2, NOxCO, CO2, NOx, THC
GPS dataRequiredOptional
Duration of test 5 to 7 times NRTC cycle work or 2 hrs5 to 7 times NRTC cycle work or
5 to 7 times NRTC CO2 mass
Data consistency: correlation between measured and calculated fuel flow rateR2 ≥ 0.90 from 15% to max fuel flow rate
MAWWork windowsWork windows and CO2 windows
Power threshold for valid windowsAverage power > 20% Pmax
If required, this can be decreased to as low as 15% in steps of 1% to achieve 50% valid windows
Average power > 20% Pmax
Proportion of valid windows≥50%
Conformity factor 2.5 for CO and NOxMonitoring only

Acknowledgements: Karsten Mathies of TÜV Hessen has graciously provided valuable guidance and background information for this article.