The Personal Centripeter—A Particle Size-Selective Personal Air Sampler

Abstract

A size-selective air sampler suitable for the measurement of personal exposure to radioactive dust is described. Sampling at 21/min, it separates coarse dust from the finer particles which are collected separately on discs of high efficiency glass fibre filter paper suitable for direct radiation counting. Suction is provided by a diaphragm pump, the rapid variation of air flow-rate being suppressed by a pulsation damper. The collection characteristic of the first stage (the cone) is such that 50 per cent of the mass associated with unit density spherical particles of diameter above 5 µm is collected; the remainder is deposited on a filter paper in the second stage. Wall losses as a function of particle size have been measured. The maximum loss (∼14 per cent) occurs on the nozzle of the cone for particles of diameter about 3 μm.