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

  • Replacement Shafts
  • Spray Headers
  • Roller Guides
  • Spray Nozzles
  • Bearings
  • V-Rings
  • V-Ring Adapters
  • O-Ring Seals
  • Leaf bags
  • Door Gaskets
  • Center Toggles
  • Front Toggles
  • Toggle Bearings
  • Chevron Seals
  • Custom Rubber Seals
  • Custom Teflon Seals
  • Filter Leaf

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 Shane, and he’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 Shane today!

Industrial Filter Media Identification

National Filter Media has the analytical equipment and expertise to identify fabric. Based on our findings you may choose to replace with the same filter media or upgrade to improve performance, reduce down time, or cut costs. Click the link to learn more.

Thanks for taking a look at FixFilters.com.  Shane has just begun building this filtration troubleshooting and basic information guide. If the article you are looking for isn't up yet, or your problem is beyond the basics, you can contact him anytime at sthomas@nfm-filter.com. Shane is happy to help or direct you to NFM's field service representative in your area.

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Industrial Filter Media Identification