This report describes the work performed to develop a design standard for calibrating number concentration measuring instrumentation for aerosol instrumentation in the ultrafine region.
Emphasis has been on achieving a robust and cost-effective capability that can be used both in specialist calibration laboratories as well as be able to be taken to the point of measurement. The potential of using accurate dilution (over a wide concentration range) as a means of providing a traceable and cost-effective means of calibrating the linearity of number-measuring aerosol instrumentation was identified as a key component of this study. An absolute dilution performance of better than 10% was identified as a design target.
A Sample Conditioning System (SCS) meeting this target has been designed and manufactured. The SCS has undergone comprehensive calibration and validation in terms of temperature and pressure sensor calibration, temperature compensation of measured pressures, flow calibration, pressure stability, leaktightness and dilution verification with a CO gas standard. An example calibration of a TSI Condensation Nucleus Counter was also undertaken utilising the SCS. The technologies (Product) described in this report will be used to establish a calibration service.