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Comparison of optical particle counting and aerosol-based particle counting technologies for UPW monitoring and diagnostics


Gary Van Schooneveld – CT Associates, Inc
Siqin He – Kanomax FMT
Pat Keady – Aerosol Devices


Liquid optical particle counting (OPC) utilizing light-scattering has been and continues to be a key technology used by the semiconductor industry to count particles in ultrapure water (UPW). Demand for detecting particle smaller than the current capabilities of these instruments has resulted in development and introduction of instruments that utilize alternate detection techniques such as acoustic emission1, laser induced breakdown detection2 and nebulization/aerosol particle counting3. Each of these techniques deploy technologies that detect particles, and potentially other forms of contamination, that differ from the OPC. Correlating the data generated by the new technologies to the historical data base available from OPC’s is important for these new technologies to gain acceptance and to understand what new and potentially insightful information may be available using these techniques.

This paper provides a direct comparison of three measurement technologies; 30 nm optical particle counting, nebulization with aerosol particle counting (10 nm scanning threshold particle counter and 5 nm liquid nanoparticle sizing system) and nebulization with precision aerosol collection and SEM/EDX analysis. Precision aerosol collection (Sequential Spot sampler) is a new aerosol technology that allows for precise collection of aerosol particles on an SEM collection media supporting the morphological and elemental analysis of aerosol particles generated by nebulization.

Five locations on a UPW system are the sample points for this comparison; post UPW distribution pump, post UV TOC reduction, post mixed bed ion-exchange, post ultrafilter and post final membrane filter. A new final polish ion-exchange resin had recently been installed on the water system along with other system upgrades and modifications.

CTA publication #132: Ultrapure Water 2017. Portland OR

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