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Pressure Leaf Filter Basics
Pressure leaf filters, or pressure vessels consist of 10 to 60 leaves, stacked inside a vertical or horizontal vessel. The leaves are drainage systems that support a wire or textile cloth cover. Since the filtration process is contained within a pressure resistant vessel, it can be an ideal solution for hazardous processes.
A filter cycle begins with the vessel sealing in the shaft and its filter leaves. Then, precoat is introduced. A precoat tank containing filtrate and filter aid (diatomaceous earth, perlite, etc.) is agitated for around 10 minutes. Then, the mix fills the vessel, vents all the air, and pressurizes. The precoat runs for 15 minutes at a fluid rate around 30- 60 gallons per square foot per hour.
After precoat, slurry is forced through the vessel under pressure. Solid particles are trapped in the precoat, or filter media while clarified liquid passes through and into a filter leaf. The liquids pass from leaf to the shaft’s interior, then out of the filter into a holding tank.
Between batches, liquid cake or sludge is drained from a valve. Dry cakes require a much larger opening, sometimes the entire vessel slides back for access to the leaves for discharge and cleaning.
Troubleshooting Pressure Leaf Filters
Torn or bent filter leaves can be the result of excessive body feed or running the filter too long between cleaning cycles. NFM can repair damaged leaves. We salvage good components and repair or replace only what is damaged. Typically a rebuilt leaf is around half the cost of new. We can repair or replace any OEM’s filter leaves.
Stop damaging your leaves by following these steps:
- Keep differential pressure at 25 to 30 PSI between cleaning cycles. Do not depend on a set time cycle.
- Cut back on the body feed.
- Only precoat the frames until the filter aid is ¼” thick.
- Check to see if your filter media has blinded.
New door gasket is leaking. If a replacement gasket was cut with straight ends, it may not create a perfect seal. Cut another with angled ends and install.
Pressure Leaf Filter Wear Parts
NFM Repairs and Recovers Leaves From Every OEM
Have you damaged leaves from your pressure leaf filter? NFM makes cloth for every OEM’s equipment. We can repair/ replace all or part of the leaf. We are happy to provide any wear part listed above.
Contact NFM, and we’ll set up a free repair order for one of your leaves. You will only pay for freight. We do this to demonstrate our craftsmanship and to provide a quote for repaired leaves as well as new replacements.
Want to save labor and shop space? Send us your leaves for bag recovery.
Still not sure how to fix your filter? We make house calls! Contact NFM today!
Contact A Technical Expert
Call us today to learn how our expertise can provide you with the filtration solution you’ve been looking for. We’ll build a relationship with you that will last well beyond the sale, providing you with unparalleled customer service and technical filtration expertise.