In a well received lecture at the American Filtration Society’s Fall Conference (5-8 October 2015), Dr Graham Rideal, CEO of standards company Whitehouse Scientific, introduced an audience of industry filtration technologists and researchers to a new way of calibrating sand screen filters to improve accuracy and reproducibility in a range of industrial applications, including automotive, pharmaceutical and oil production.
The company’s revolutionary new PoreSizer™ enables image analysis techniques to be used for particle size and shape measurement when undertaking challenge testing of these filters. This allows the elimination of any non-spherical particles from pore size calculations, increasing confidence in all test results.
The image analyser can also measure for the first time the geometric pore sizes of plain weave test sieves rather than the current method of measuring only the wire spacings in the warp and weft directions, enabling wire count and open areas to be accurately determined.
Sand screen filters are complex 3-D steel meshes that are used to separate sand particles from other materials, and are widely used in a range of industries, including large pore size sand screens used in oil extraction down to five micron twilled meshes used in pharmaceutical applications. The technology is extended into the sub-micron region using centrifugal methods of analysis.
If the sand screen used has apertures that are too large, the abrasive sand can pass through and damage pumps and pipelines. If too small, flow rates are uneconomically low and the filter can blind or plug.
The complexity of the filter materials precludes the use of direct microscopy to measure pore size, so a challenge test has been developed whereby the filter is challenged with real particles - both sonically fluidized (dry) and ultrasonically fluidized (wet) - and the maximum sizes of the particles passing through is measured.
In his presentation The Latest Developments in Determining the Geometric Pore Sizes of Filter Media using Precision Microspheres in Conjunction with a New Image Analyser, Dr Rideal outlined Whitehouse Scientific’s PoreSizer™ technology, describing how it provides users with a highly accurate, rapid and repeatable method for the certification of sand screen cut points using precision glass beads.
“The accuracy and reliability of measurement provided by the new PoreSizer™ will support important commercial decisions in a wide range of industrial applications, and is particularly pertinent following recent high profile failures of filters in the automotive sector,” said Dr Rideal. “This technique replaces the measurement uncertainty of previous methods, which made it almost impossible for meaningful lab to lab comparisons in the past.
“Whitehouse Scientific is the leading European certification laboratory for primary methods of particle size analysis and it was an honour to be invited across ‘The Pond’ to introduce this latest research and ground-breaking new technology. Filter manufacturers are now beginning to adopt Whitehouse Scientific’s certification methods as being the most accurate and independent validation of their products.”
To obtain a copy of Dr Rideal’s paper, The Latest Developments in Determining the Geometric Pore Sizes of Filter Media using Precision Microspheres in Conjunction with a New Image Analyser , and for more information about Whitehouse Scientific’s full range of products and services visit www.whitehousescientific.com.