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Neva-Clog Screens

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The Neva-Clog is a unique welded, high strength screen free of internal plugging. It consists of two sheets of light gauge metal in which circular perforations are made in a predetermined hole diameter and spacing. The sheets are joined by spotwelding in a specific pattern, dependent on the medium's application. This welding pattern, besides assuring uniform joining of the sheets, controls the functional characteristics of the medium.

Although originally developed as an underdrain material, Neva-Clog has found wide use as the filter media on pressure and vacuum filter leaves. It is often used with round or rectangular leaves and flat or conical underdrains. It provides fast precoating, easy cake release and easy leaf cleaning due a smooth surface. Neva-Clog resists abrasion and abuse during cleaning or acid washing. As the chamber material, Neva-Clog becomes a general purpose filter leaf for many applications when used with WEDGE-FLOW or Por-O-Septa.

Neva-Clog is used as a support for granular activated carbon in processing columns for removal of colors, odors, and tastes. It's strength and performance characteristics have resulted in its installation in sugar, chemical, petrochemical and food refining plants. Because of its rigidity, compared with woven media, it requires minimum undersupport and no protective top screen. Neva-Clog's particle retentivity, in the range of 100 mesh, enables it to handle all corresponding granular carbon and bone char. It's strength and freedom from internal plugging insure long service life, making it especially valuable for towers in inaccessible locations or in hazardous service. Neva-Clog is also used for underdrains in catalyst towers, resin towers and ion exchange units.


Operating Principle

Fluids pass through the holes of thetop sheet, turn at right angles to passthrough the controlled spacingbetween the sheets, then turn again atright angles to pass through the holesin the bottom sheet. Solids too large topass through are retained on thesurface. Finer particles are retained bythe formulation of a filter bed or cakeNeva-Clog operates best with freedraining solids or as a supportingmedium for precoat material.


Abrasion resistant
Abuse resistant

Easy cake release

Easy leaf cleaning

Fast precoating

High strength

Long service life


Smooth surface


Neva-Clog can be produced in any commercially available sheet metal possessing the proper perforation and welding characteristics.


Grade I is used for coarse retention
Grade II is used for finer retention

Grade III is used wherea flatter surface is desired, such as on filter leaves

The “back-to-back” isused where more restricted and moreequally distributed flow is desired

Filter Leaf Designs

Bottom outlet, Bar Frame, Welded

Bottom outlet, 966 Binder, Welded

Filter Leaf Constructions

Neva-Clog Filter Media, Por-O-Septa® Chamber, 966 Binder
Neva-Clog Filter Media, Wedge Wire Chamber, Bar Frame wi:h Reverse "U"

Underdrain Designs

  • Flat
    Neva-Clog is ideal for permanent installation in flat tower bottoms. Discs may be rolled up for insertion through manways for easy installation.
  • Conical
    Particularly suited to conical bottoms, Neva-Clog's smooth surface facilitates discharge of solids.
  • Underdrain Constructions

  • Neva-Clog Filter Media, Wedge Wire Support Screen, Multi-Grate Sub-support
  • Neva-Clog Filter Media, Por-O-Septa Support Screen, Multi-Grate Sub-support
  • Applications

    Catalyst towers
    Filter Leaves

    Ion exchange units

    Resin towers


    Industries Served


    High Fructose

    Oil Additives


    Soda Ash


    Wastewater Treatment

    Water Treatment



    Neva Clog Retention and Flow Data
    (JPG, 61KB)

    (PDF, 178KB)

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