Calibration Uncertainty of 23nm Engine Exhaust Condensation Particle Counters with Soot Generators: a European Automotive Laboratory Comparison

Abstract Calibration of condensation particle counters (CPC) to measure non-volatile number (PN) from vehicle emissions is a significant source uncertainty the regulated measurements. In this work, calibration automotive and laboratories was determined in first-of-its-kind comparison. For purpose, counting efficiency reference CPC for exhaust emission measurements at seven participants across Europe with ten soot aerosol generators. found be very different CPC’s cut-off regime (around D 50 23nm) coefficient variation (CoV) 11% plateau (from 90 41nm upwards) CoV 4.5%. The higher group generators poorly optimized operating points 31% 23nm 5.8% ≥41nm. Specific influence factors on (measured as inter-lab variability) could identified. laboratories’ accounted most variability regime, while 20% attributed sample flow measurement. Differences between were main cause due increased material sensitivity size but had only secondary relevance regime. inter-laboratory exercise should guideline users legislators, it provides typical value expected measurement PN.