A condensation particle counter insensitive to volatile particles

•A new type of condensation particle counter is introduced that does not measure volatile particles.•A range of working fluids with attractive properties for the new CPC are investigated.•Working temperatures of over 300 °C have been demonstrated.

A High Temperature Condensation Particle Counter (HT-CPC) is described that operates at an elevated temperature of up to ca. 300 °C such that volatile particles from typical combustion sources are not counted. The HT-CPC is functionally identical to a conventional CPC, the main challenge being to find suitable non-hazardous working fluids, with good stability, and an appropriate vapour pressure. Some key design features are described, and results of modelling which predict the HT-CPC counting efficiency. Experimental results are presented for several candidate fluids when the HT-CPC was challenged with ambient, NaCl and diesel soot particles, and the results show good agreement with modelled predictions, and confirm that counting of particles of diameters down to at least 10 nm was achievable. Possible applications are presented, including measurement of particles from a diesel car engine and comparison with a near PMP system.