Automatic Flushing Strainer-Type Filter: A Method for Actual Filtration Grade Assessment

Proper filtration selection, sizing, maintenance, and performance of a filtration system are crucial for removing suspended solids in water, preventing clogging of emitters, and ensuring a high-performing microirrigation system throughout its lifespan. Filtration prevents the intake of particles larger than the pore size specified in a given filtration grade. Proper selection of the filter media ensures efficient solid–liquid separation. Strainer-type or screen filters have elements composed of a woven or nonwoven cloth of numerous weave types. The material and characteristics of the screen directly affect the fluid flow and filter performance. The aim of this study is to propose a method for determining the actual filtration grade of filters used for irrigation. An automatic flushing strainer-type filter was equipped with five filter element models, composed of woven and nonwoven materials, for evaluation. A new methodology was developed to assess the actual filtration grade based on the removal efficiency for suspended solids under controlled and repeatable conditions. The removal efficiency of each filter element was determined for particle size ranges defined according to the filtration grade declared by the manufacturer. The proposed methodology allowed for the assessment of the actual filtration grade of each model of filter element operated with water containing suspended particles of silica sand. The filtration grade declared by the manufacturer was confirmed for some of the filter elements, but it could be modified for others. The proposed methodology could be useful for assessing the actual filtration grades of screen, disk, and media filters.