A NOVEL TECHNIQUE FOR ESTIMATING THE EFFECTIVE PORE SIZE AND OPEN AREA OF DENSELY WOVEN FILTER FABRICS

摘要

Densely woven multifilament filter fabrics (cover factor greater than 1) have been the standard in solid/liquid separation for decades.The effective pore size of a filtration fabric is an aggregate measure of the pore size distribution which,together with the total open pore area,determines the fluid flow resistance of a fabric.It also gives an indication of the size of solid particles that can be retained on the fabric.For monofilament fabrics having a cover factor less than 1 the effective pore size and fabric porosity are routinely estimated from the construction parameters of weave and yarn.However,for multifilament fabrics with cover factor greater than 1 the fluid flow inside the fibre yarns becomes important because the pores in between the yarns are squeezed to the minimum.Even with the most modern porometers it can be difficult to measure the intra-yarn pore size and total pore size area accurately.Consequently,different permeability measurements,and not pore size measurements,have become the standard in evaluating their filtration performance and particle retention.Permeability,however,is a function of many variables and does not correlate directly with effective pore size.The purpose of this study is to present a new method for estimating the effective pore size and open pore area of a densely woven multifilament fabric.The method is based on a combined use of standard textile analytical methods and modelling of liquid flow through a fabric.Measured fluid permeability,fabric electrical resistance and fabric thickness were used in the developed model to calculate the effective pore size and the total open area.The results are validated by comparing them to the measured bubble point pore size (largest pore size) and average pore size of the fabric.The developed model shows good correlation with measured values.