126 A Laboratory Procedure and a Recording System for the Maintenance of Personal, Hand-Held and Benchtop Time-Resolved Aerosol Instruments

Abstract

Abstract The HSE Science and Research Centre use time-resolved instruments to collect aerosol data for research and to support the sampling of aerosols in workplace environments. The performance of these instruments (traditional and low cost sensor devices) is dependent on regular maintenance and calibration. However, it can deteriorate within the recommended manufacturer calibration period, particularly if they have been exposed to high concentration of dust, or exposed for extended periods. This poster will describe the practical strategy developed at HSE for the maintenance of time-resolved devices and the lessons learnt. HSE owns a range of hand-held or compact time-resolved instruments, which are optical particle counters (OPCs), condensation particle counters (CPCs), diffusion chargers as well as photometers measuring particle number, surface area and mass concentrations. Some of the instruments are size-resolved devices. Photometers and OPCs were benchmarked using SPHERIGLASS ® A- 5000 in a calm-air chamber for a wide range of concentrations against a dedicated reference photometer or OPC, not necessarily of the same model or size range characteristic. For devices, measuring in the nanometre size range (CPCs and Diffusion Chargers), a salt nanoparticle aerosol was generated using a Collison nebulizer and a CPC used as the reference. Acceptable tolerances from the reference concentration were established for the CPCs and Diffusion Chargers. For each photometer model, an average ratio of the evaluated photometers concentrations by the reference photometers concentrations was calculated and a linearity plot of the photometer concentration versus the reference photometer concentration was established. © Crown Copyright (2022)