Condensation Particle Counter Proportionality Calibration from 1 Particle·cm⁻³to 10⁴Particles·cm⁻³

Abstract

This article presents a process to calibrate a condensation particle counter (CPC) over the concentration range from 1 particle·cm −3 to 10 4 particles·cm −3 with traceability to SI units as realized by the National Institute of Standards and Technology (NIST). The process combines two independent steps: a proportionality assessment over the range of the CPC using a consistent diluter and an absolute calibration of the CPC with an aerosol electrometer (AE) at high concentrations. The proportionality assessment, which is the focus of the article, is analogous to the attenuation method for testing the proportionality of high-power laser detectors. This procedure tests the proportionality of one CPC by itself and does not require the use of a calibrated reference CPC. The primary calibration of the CPC with the AE at high concentrations allows for an absolute calibration with NIST traceability, resulting in a simple one-parameter correction to the measured CPC data. The proportionality test enables uncertainties to be assigned to the CPC over an extended range of concentration beyond the lower detection limit of the AE, thereby establishing measurement traceability for low concentrations. The relative expanded uncertainty of the CPC with a coverage factor of k = 2 is 2.8% over the range of about 1 particle·cm −3 to 10 4 particles·cm −3 .

Measurement of Automotive Nonvolatile Particle Number Emissions within the European Legislative Framework: A Review

“…Note that the comparison with an electrometer is seldom undertaken below 1,000 p/cm 3 , so information for lower concentrations regarding the linearity is lacking. However, recent studies in this area show that PNCs are linear, or at least there are ways to check their linearity for concentrations <1,000 p/cm 3 using a collection of particles on filters and TEM images (Fletcher et al 2009) or stepwise dilutions (Owen et al 2010;Sakurai and Ehara 2010). Checking the linearity of PMP PNCs with a reference PNC has shown that it is typically within 7% above 10 p/cm 3 (Giechaskiel and Bergmann 2011), and nonlinear responses >10% are rarely observed.…”

Traceable methods for calibrating condensation particle counters at concentrations down to 1 cm−3

“…To overcome this issue, Owen et al [6] used a fixed diluter to verify the proportionality of their CPC from 1 cm −3 to 10 4 cm −3 . Traceability to the SI was achieved by comparing the CPC to an FCAE at high concentrations, fixing the constant of proportionality.…”

Extending the Faraday cup aerosol electrometer based calibration method up to 5 µm

“…Above this, the multiple charging limits the precision. However, there are methods to limit this issue, for instance, an additional aerodynamic size selection (Romay-Novas and Pui 1988; Hillamo and Kauppinen 1991;Owen et al 2012) or modifications of the La Mer generator (Sinclair and La Mer 1948), which produce singly charged particles (Uin et al 2009;Yli-Ojanper€ a et al 2010;Yli-Ojanper€ a et al 2012). In 2012, Yli-Ojanper€ a et al successfully applied a modified La Mer generator and a DMA for producing singly charged calibration aerosol and for conducting a FCAE-based number concentration calibration up to 1 mm.…”