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
- 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
- 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’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.