Determination of Filtration Grade in Woven Screen Filters: Influence of Material, Weave Pattern, and Filtration Rate

Screen filters are widely used to retain suspended solids. Their performance depends not only on the nominal aperture size but also on the structural characteristics of the filter element, including material properties, weave pattern, and filtration rate. Although manufacturers typically specify filtration grade using mesh size or micron rating, these nominal values sometimes fail to reflect actual retention efficiency under field conditions. This study evaluated how filtration rate influences the retention efficiency of inorganic particles in eleven woven screen filter elements with different materials and configurations. Tests were conducted under two filtration rates and using particles of different size classes to determine the actual filtration threshold. The removal efficiency was determined by measuring total suspended solids (TSS). Eight of the eleven filters achieved more than 85% efficiency for at least one particle class, while three failed to meet this criterion. Higher filtration rates tended to reduce particle retention, particularly in synthetic filters. Nylon and polypropylene elements often exceeded their nominal filtration grades but were more sensitive to flow variations. Stainless steel filters exhibited consistent performance aligned with specifications. The findings emphasize the importance of experimental validation and support more informed filter selection based on particle size and hydraulic operating conditions.