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
Parameter	China Stage IV	EU Stage V
Temperature, min.	10°C	-7°C
Temperature, max.	38°C	-0.4514·(101.3-p_b) + 311 K where p_b is the ambient pressure, kPa
Altitude max.	1700 m	Ambient pressure ≥ 82.5 kPa
Start of evaluation	Coolant > 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
Pollutants	CO, CO₂, NOx	CO, CO₂, NOx, THC
GPS data	Required	Optional
Duration of test	5 to 7 times NRTC cycle work or 2 hrs	5 to 7 times NRTC cycle work or 5 to 7 times NRTC CO₂ mass
Data consistency: correlation between measured and calculated fuel flow rate	R² ≥ 0.80 from 15% to max fuel flow rate	R² ≥ 0.90 from 15% to max fuel flow rate
MAW	Work windows	Work windows and CO₂ windows
Power threshold for valid windows	Average power > 20% P_max If required, this can be decreased to as low as 15% in steps of 1% to achieve 50% valid windows	Average power > 20% P_max
Proportion of valid windows	≥50%
Conformity factor	2.5 for CO and NOx	Monitoring only

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