Design Factors

PolyGrid® Expanded Polymers for Membrane Support

Separation and purification are key criteria for industries that process water, food & beverages, chemicals, and pharmaceuticals. Dexmet custom manufactures all PolyGrid® materials with a multitude of open area designs with controlled pore sizes to provide a more consistent flow rate for your filter application.

If your filter application has a critical upstream/downstream or cross flow requirement, our Engineering Department will partner with you to develop the optimum design to maximize performance and workability. Whether it’s improving liquid flow rate, air flow, strength, or particle retention, Dexmet can provide a material that will give your design the performance advantage.

Applications

  • Membrane Support
  • Separation and Backing
  • Primary Purification

Advantages

  • Assured Media Integrity & Pleat Spacing Even Under Dynamic Flow
  • Increased Filter Surface Area for Pleated Designs (Capability to Expand Thinner Materials to Achieve a Reduced Overall Thickness)
  • Materials Laminate for Contraction, Co-Expansion, and Flex with Filter Membranes (Material Compatibility with Membranes)

Features

  • Pore Size Starting at 25 Microns (.001”)
  • Base Material Thickness Down to .025mm (.001”)
  • 1300+ Openings/cm²
  • Widths to 610 mm (24”) (Wider Widths May Be Available Depending on Material)

Common Materials

Fluoroplastics:

PTFE, PP, PE, PFEP, PCTFE, PVF, PVDF, PFA and ECTFE

Polyamides:

Nylon 6 and Nylon 6.6, PEEK

Polyolefins:

PE and PP

Polyesters (Thermoplastic):

PET, PETP, PBTP

Polysulfones

Polyvinyls

High Temp Plastics:

PTFE, PEEK, Nylons

Purpose

Filters that are designed to remove fine particulate (less than 0.1 mm) frequently employ non-woven filter media that requires mechanical support within the filter body. The support must provide adequate strength while not significantly reducing the flow of the fluid to be filtered.

Design Considerations

  • Filtration Rating: Particulate passage is controlled by the opening size or “pore” diameter of the media and is designated by a Micron rating. The opening configuration (pore) might be diamond-shaped (expanded), square (woven wire), or round (perforated). Designate the opening according to the particle size required to be separated out of the flow path.
  • Backpressure: Flow backpressure results from the “percent open area” and the degree of particulate build-up on the media surface. Choose a material that will more than withstand the full pressure drop across a blocked surface area.
  • Filter Strength: Ultimate strength is controlled by material selection, thickness, percent open area and pore geometry. Multiple layers of filter material with varied openings can improve flow, purification, and withstant higher backpressures.

Dexmet® PolyGrid® over Alternative Materials

  • Dexmet’s precision expansion process ensures high reproducibility leading to a more consistent final product and lower cost of quality.
  • Dexmet can produce “open” polymer sheets of fluoropolymers (such as Teflon) that resist extrusion.
  • Dexmet’s manufacturing process can achieve typical widths up to 24”. Wider widths may be available for certain materials.
  • Extruded plastic is the most commonly used material for filter media support. Extruded material is generally lower in cost per unit area than expanded plastic. However, some polymers (most notably the fluoropolymers, such as Teflon) resist extrusion. In cases where these resins are required, expanded material is the preferred design choice.
  • Woven material can achieve smaller pore sizes than either expanded or extruded products. However, material selection is very limited and more difficult to fabricate, which can lead to quality and/or manufacturing problems. In addition, the strand can move under flow conditions changing the geometry of the opening and potentially allowing larger particles to pass through.

MicroGrid® Expanded Metals for Membrane Support

If your filter application has a critical upstream/downstream or cross flow requirement, our Engineering Department will partner with you to develop the optimum design to maximize performance and workability. Whether it’s improving liquid flow rate, air flow, strength, or particle retention, Dexmet can provide a material that will give your design the performance advantage.

Applications

  • Internal Core Material: Media Support & Backing
  • Primary Filtration
  • Pre-Filters

Advantages

  • Economical Option to Alternative Materials
  • Uniform Material: One Piece Homogenous Design (Assures media integrity under dynamic flow conditions)
  • Engineered Pore Sizes to Achieve Flow, Pressure Drop, and Collapse Pressure Requirements

Features

  • Pore Size Starting at 25 Microns (.001”)
  • Base Material Thickness Down to .025mm (.001”)
  • 1300+ Openings/cm²
  • Widths to 1200 mm (48”)

Common Materials

Stainless Steel, Aluminum, Nickel Alloys, & Carbon Steel (FE).

Dexmet has the capability to expand all ductile metals.

Purpose

Filters (or pre-filters) that are designed to remove large particulates (over 0.5 mm in diameter) must be made to withstand impact stresses as well as fluid pressure. “Open” (expanded, perforated or woven wire) metal foils are frequently used for this function because they can be easily formed for the specific application.

Design Considerations

  • Filtration Rating: Particulate passage is controlled by the opening size or “pore” diameter of the media and is designated by a Micron rating. The opening configuration (pore) might be diamond-shaped (expanded), square (woven wire), or round (perforated). Designate the opening according to the particle size required to be separated out of the flow path.
  • Backpressure: Flow backpressure results from the “percent open area” and the degree of particulate build-up on the media surface. Choose a material that will more than withstand the full pressure drop across a blocked surface area.
  • Filter Strength: Ultimate strength is controlled by material selection, thickness, percent open area and pore geometry. Multiple layers of filter material with varied openings can improve flow, purification, and withstand higher backpressures.
  • Flow restriction is determined primarily by “percent open area” and secondarily by hole geometry.
  • Resistance to corrosion and/or thermal deformation is controlled primarily by material selection.

Dexmet MicroGrid® over Alternative Materials

  • Dexmet offers a wide range of expanded metal foils and can produce rolls up to 1,200mm (48”) in width.
  • Dexmet’s precision expansion process ensures high reproducibility leading to a more consistent final product and lower cost of quality.
  • Dexmet’s expansion process produces more finished product per pound of raw material than perforation. Scrap is also minimized because there is virtually no waste. The expansion process is the preferred choice when your design utilizes expensive, hard to procure materials.
  • Woven material can achieve smaller pore sizes than either expanded or perforated products. However, woven material has a tendency to “unwind” at the edges, which can lead to quality and/or manufacturing problems as well as safety issues. More importantly, the strands can move under dynamic flow conditions changing the geometry of the opening and potentially allowing larger particles to pass through.

Contact Us

Phone: (203) 294-4440
Fax: (203) 294-7899

sales@dexmet.com

22 Barnes Industrial Rd. So.
Wallingford, CT 06492
United States of America

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