Comparative liquid flow studies in filter media

M. Ängeslevä*, R. Salmimies, A. Häkkinen, Lappeenranta University of Technology, Finland; G. Rideal, Whitehouse Scientific Ltd, UK

Water permeability is one of the most important characteristic of cloth filter media. The study of this characteristic is of great importance from the perspectives of both the design of the filter cloth itself and the operation of the whole filter. Cloth manufacturers usually provide their customers with the value of air permeability only. However, this single value might not be suitable for describing the separation performance of the cloth in solid/liquid separation where the fluid is obviously not air. Moreover, despite the fact that the fluid mechanics through porous beds are fairly well known and equations for permeability exist, standardized methods for measuring liquid permeability of filter media do not exist. The aim of this work is to present, to describe and to compare different methods for measuring the water permeability of cloth filter media.

A total of 15 plain cloth filter samples with square weave mesh were woven for the tests. Mean aperture size for the samples ranged between 16 and 250 microns. The geometric pore size based on the nominal wire diameters and warp and weft specifications were calculated by Math2Market software. Image analysis using the Whitehouse Scientific PoreSizerTM was used to verify the geometric pore sizes as well. The pore size distributions of the cloth samples were determined by using two commercial capillary flow porometers. Liquid permeability was measured by using two differing equipment. The first technique measures the liquid permeability under a declining pressure that starts from 0.5 bar and decreases to 0.1 bar during the measurement. The second method used was the Whitehouse Scientific AquaPoreTM, a new programmable aqueous Porometer where all measurement parameters were traceable to International Standards.

The use and the comparison of different methods for the measurement of the pore size distribution and water permeability and for the calculation of the geometric pore size of the cloth filter media enables to evaluate their suitability and the accuracy of obtained data. These data contributed to a more detailed analysis of the flow behavior through filter cloth and this in turn could be further used for the investigation of the relationships between the different parameters.

Session: F1 - Filter Media - Quality Control and Pore Size Analysis I
Day: 13 March 2018
Time: 13:00 - 14:15 h

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