1988 Volume 3 Issue 1 Pages 49-59
Methods of particle analysis and questions of data interpretation are discussed for cylinder gases with high initial pressure levels. It is shown that commercial pressure regulators tend to be relatively strong sources and sinks for particles. However, critical orifices are found to be useful for particle sampling from high pressure sources without altering the characteristics of the source by impaction losses or by resuspension of particles. Particle concentrations in cylinders are shown to follow exponential decay laws governed mainly by sedimentation. Particle levels are extremely sensitive to cylinder handling history. Changes from 10/ft3 to 105/ft3 (approx. 10-4/cm3 to 10/cm3) are observed in conventional uncleaned cylinders filled with N2, resulting from movement or mechanical shock of the cylinder body.
