Pressurized Screen Filters
Pressurized Screen FiltersA pressurized screen filter may be the most economical choice for groundwater filtration, since it is effective at removing inorganic material. It is not as effective with surface water that contains large amounts of organic matter. Organic material can quickly clog a screen filter, making frequent cleaning necessary. Under such conditions, a sand media filter or a screen filter with automatic backflushing is recommended.
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.