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EURAMET comparison 1244. Comparison of aerosol electrometers (Final Report).

Quincey, P G; Sarantaridis, D; Yli-Ojanperä, J*; Keskinen, J*; Högström, R*; Heinonen, M*; Lüönd, F*; Nowak, A*; Riccobono, F*; Tuch, T*; Sakurai, H*; Owen, M* (2014) EURAMET comparison 1244. Comparison of aerosol electrometers (Final Report). NPL Report. AS 85

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Abstract

Aerosol particle number concentration has recently featured in vehicle emission legislation and is becoming increasingly important in other areas such as ambient air monitoring. Number concentration measurements are also often integral to particle size distribution measurements, such as when using a Mobility Particle Size Spectrometer.

The draft ISO standard ISO/DIS 27891 [1] describes a calibration procedure for Condensation Particle Counters (CPCs - the usual type of instrument for measuring particle number concentration in the size range from a few nanometers to a few micrometers) by reference to an aerosol electrometer. If a source of singly-charged particles is used, number concentration (typically in units of cm-3) is directly comparable to charge concentration (eg in fC.cm-3). The DIS refers to the role of NMIs in providing certification for both reference aerosol electrometers and reference CPCs.

The aim of this comparison was to compare the results of different laboratories' measurements of charge concentration - in practice the combination of electrometer current (eg in fA), air flow (eg in cm3.s-1) and any losses of particles within the instrument.

The comparison took place at the Tampere University of Technology in March 2013 as part of the EMRP project ENV02 PartEmission (Automotive combustion particle metrics), Deliverable 1.2.2.

Because this is the first multi-NMI comparison of aerosol electrometers, EURAMET participants were joined by other participants with strong metrological expertise in this area.

The comparison included aerosol charge concentrations between about 0.15 and 3 fC.cm-3, and aerosol particle sizes from 6 to 200 nm, using aerosol particles composed of di-octyl sebacate, NaCl and soot. The results suggest that, away from low charge concentration and low particle size, agreement to ±2% between reference laboratories using different designs of instrument is already typical, and that uncertainties of less than ±1% (2s) are readily achievable.

Item Type: Report/Guide (NPL Report)
NPL Report No.: AS 85
Subjects: Analytical Science
Analytical Science > Trace Analysis and Electrochemistry
Last Modified: 10 Sep 2018 13:44
URI: http://eprintspublications.npl.co.uk/id/eprint/6101

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