OVERVIEW

The design of many of the instruments used for measuring aerosol properties depends on the particle transport and optical properties discussed in the previous chapters. The principal applications of measurement systems are to atmospheric measurements, the monitoring of air pollution, the testing of gas cleaning equipment such as filters and scrubbers, and the monitoring of process streams including stack gases. Theory provides useful guidelines for instrument design, but it is rarely possible to predict instrument performance from first principles. It is almost always necessary to calibrate the instruments using aerosols of known properties.

A comprehensive review of measurement methods is beyond the scope of this book. Excellent reviews of aerosol instrumentation have appeared in recent years (Spurny, 1986: Pui and Liu, 1988; Willeke and Baron, 1993; ACGIH, 1995). A practical guide to aerosol chemical analysis is given in the book edited by Lodge (1989). Much information on the sampling and analysis of the atmospheric aerosol can be found in the EPA (1996) Air Quality Criteria Document for particulate matter. The measurement methods discussed in this chapter provide information on a broad spectrum of physical and chemical properties. The discussion starts with basic sampling methods and microscopy, goes on to integral measurement methods including mass and number concentrations and total light scattering, and finally to instruments that provide more detailed information on size distribution and chemical properties. Instruments with different sensing systems will, in general, have different response times, and the aerosol properties measured by each only partially overlap. A...