Analytical methods for determination of aerosols by means of membrane ultrafilters. VIII. Determination of the mean pore size by gas flow rate measurements

Aerosol filtration by means of Nuclepore filters: structural and filtration properties

“…As in previous studies (Hampl and Spurny, 1966), it was necessary to consider three regimes of gas flow through the pores of the filter. If, as usual, the Knudsen number is represented by Kn = l/R where l = mean free path in centimeters and R = pore radius in centimeters, then for the viscous flow region, where Kn << 1, the pressure drop may be represented by the Hagen-Poiseuille equation in the form: Ap = Pi ~Pi Vl -5.093 (vL/p1)(q/R04Nll) (1) where p1 = gas pressure before the filter, dyne/sq.…”

“…Fiber filters, the true filter papers, have been known longest, are the least expensive, and are probably the most widely used. In the past 20 years, the so-called membrane filters have been available and their properties and uses have been described and verified (Spurny. .…”

“…Permanent affiliation, Czechoslovak Academy of Sciences, Institute of Physical Chemistry, Prague. (Millipore Corp., 1968;Spurny, , 1966. The substantially different properties of Nuclepore filters (Spurny, Lodge, et al, 1969) raised questions as to their competitive use for the same sorts of tests as the membranes.…”

Hydraulic permeability of open‐cell hydrophilic polyurethane foams

“…In addition, the foams are compressible so that foam length decreases with increasing pressure and, more importantly, porosity decreases. Since the foams are restrained laterally during flow measurement, only uniaxial compression needs be considered so that (4) where L = foam length at pressure AP, Lo = foam length at zero pressure (original length), and E = compression modulus of the foam.…”

Comparative review of efficiency analysis for airborne solid submicrometer particle sampling by nuclepore filters

“…In the beginning, the filtration theories were explained by Fleischer et al (1965) and Price and Walker (1962). Then Spurny summarized a series of theoretical models (Hampl and Spurný, 1966;Spumy and Pich, 1965;Pich, 1963, 1965;Spurny and Pich, 1964) and developed the most classic one (Spurny et al, 1969). Smith et al (1976) pointed out that besides diffusing on the wall of filter pores, particles can also diffuse onto the surface of filters, which has been proved to be of great significance.…”