Advancements in Techniques for Calibration and Characterization of In Situ Optical Particle Measuring Probes, and Applications to the FSSP-100 Probe

Abstract

Advancements in techniques for the operational calibration and characterization of instrument performance of the Particle Measuring Systems, Inc. (PMS), forward scattering spectrometer probe (FSSP) and optical array probes (OAPs) are presented, which also can be used for most in situ particle-measuring optical probes on the market. These techniques include the determination of a distortion matrix to correct for instrumental broadening of the measured particle size distribution. A new version of a monodisperse droplet generator is introduced for absolute calibration in the size range between 10 and 100 ?m. In addition, a high-speed technique was employed for the determination of airspeed influence on the sample volume and the sizing of particles. The calibration of a PMS FSSP with real water droplets may be significantly different from the usual calibration with glass beads. High-speed measurements simulate particles at speeds of up to about 250 m s?1. Particle undersizing and the decrease of the sample volume with increasing airspeed are described. The use of the modular tools, built for this work, is discussed for probe alignment, functionality checks, and general characterization and diagnostics both in laboratory and field environments.