Pressurized Screen Flters
The performance of a screen filter depends on the quantity of suspended material, the mesh size, the flow rate, and the dimensions of the screen surface. Available mesh sizes range from 20 to 450 mesh.
The maximum recommended flow rate generally ranges from about 150 to 200 gallons per minute per square foot of filter, depending on the manufacturer. The recommended design pressure loss is 3 to 5 psi. The screen should be cleaned manually or automatically whenever the pressure loss across the filter has increased by 3 to 5 psi.
Several companies manufacture screen filters with automatic backflushing systems. One configuration consists of a bank of two or more screen filters. During backflushing, the flow is reversed using clean water from the other screen filters; the backflushed water is discharged through the backflush port. Another configuration uses water jets from nozzles inside the screen to wash off any accumulated material.