how to select the proper filter cloth for your application

FILTER CLOTH SELECTION GUIDE

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Identifying the correct type of filter cloth involves understanding the specific characteristics of the slurry and the filtration demands of your application. Here are several critical factors that we assess during the selection of filter cloth.

Reach out to M.W. Watermark for assistance in recognizing or evaluating these factors.

• Is the cake or filtrate the end product?
• What is the pH level?
• Temperature of the slurry?
• Size of the slurry particles?
• Is the slurry pre-treated (e.g., with Polymer, DE, Ferric, Lime)?
• Are there abrasive, coarse particles present?
• Do solvents, oils, or greases exist in the mix?
• How many filtration cycles occur daily?

This information helps to identify:

• Compatible raw materials for the fabric
• The type of yarn (fibers) needed
• The appropriate weave type
• The finishing treatments required for optimal filter cloth performance

COMMON FILTER CLOTH MATERIALS

Polypropylene

As a widely accepted standard for filter cloth, polypropylene excels in various applications. It can handle elevated temperatures, resists blinding (weave clogging), and boasts a smooth surface to facilitate easy cake removal. However, it’s essential to analyze the slurry's composition before selecting polypropylene. For instance, if bleach is present in the slurry, polyester filter cloth materials would be a better fit. Additionally, latex borders can be applied to non-gasketed cloth to enhance sealing under pressure.

Nylon

This robust fiber is preferred for its resilience against abrasives. Although it is pricier, nylon blends provide such durability that the investment is justified through extended service life.

Polyester

Polyester is favored when operating temperatures exceed 180 degrees, or in the presence of oxidizing agents.

FILTER CLOTH FIBER TYPES

Manufactured using synthetic fibers, filter cloths can be classified into various types:

• Monofilament: This type consists of a single, smooth, continuous extrusion. It offers the highest flow rates, good resistance to blinding, and excels in abrasion and scaling resistance. Typical fiber diameters range from 4 mil to 10 mil (.004 to .01). It provides the best cake release.

• Multifilament: This features multiple continuous fibers twisted together into one yarn, offering excellent retention of small particles and good cake release properties.

BRIGHT offers additional products and information that you may find useful.

• Staple (Spun): Forms from short lengths of fibers (similar to cotton) that are spun into yarn, resulting in a “hairy” texture. It provides the best solids retention, though it has the poorest cake release.

FILTER CLOTH FABRIC WEAVES

• Satin: Characterized by a smooth surface from layering the warp yarn over multiple weft yarns, this weave minimizes intersections. It is flexible, adapts well to curves, and is well-known for excellent cake release with average particle retention.

• Twill: The twill weave incorporates a diagonal pattern for enhanced strength, though it compromises some stability. The cake release and blinding resistance are average.

• Plain: As the simplest weave, the plain weave alternates weft and warp threads, resulting in average strength, cake release, and stability, while exhibiting high particle retention and low blinding resistance.

ADDITIONAL WEAVE MYRIAD

• Leno Weave: This involves intertwining two or more warp threads, creating a 'locking' weave that primarily prevents fiber shifting in open weave fabrics. Typically used in backing cloths.

• Basket Weave: An adaptation of the plain weave where multiple warp and weft yarns cross each other, providing more strength at the cost of stability. Commonly found in backing cloth or applications needing added strength.

FABRIC FINISHING

Finishing processes enhance the cake release, filtration quality, and stability of the fabric.

• Singeing: This method removes surface fibers from staple and felt fabrics to improve cake release efficiency.
• Calendaring: Utilizing heated compression rolls, this process 'melts' the fabric to manipulate permeability and ensure a smoother cake release surface.
• Heat Setting: Achieved through wet or dry methods to create a stable fabric that resists shrinking or stretching.

Contact M.W. Watermark for a thorough discussion regarding your specific application.

Micronics customizes filter cloth solutions based on the precise process parameters you provide. Often, our advice stems from rigorous filtration testing results. Should your operational processes evolve, we recommend conducting a fresh evaluation of the filter cloth specifications to match new conditions. Customers frequently discover that even minor adjustments in their processes compel a reassessment of their filter cloth needs to ensure optimal filter press functionality.

For example, did you know that altering a chemical or physical treatment could significantly impact your filter press’s efficiency?

Filter cloths come in various materials including polypropylene, polyester, cotton, and other synthetic variants. They can be composed of monofilament fibers, multifilament fibers, or staple fibers. To gain more insight into filter cloth terminology, please check our latest blog post.

The smooth surface of monofilament fibers enhances cake release capabilities. The uniform diameter of corded fibers allows for the production of fabrics with consistent pore sizes.

Multifilament and spun fibers are created by twisting multiple smaller diameter monofilament fibers together, typically suited for fabrics requiring a tight weave where high flow rates are less critical.

When selecting the appropriate filter cloth, pore size is crucial. It is influenced by fiber quantity and size, as well as the weave type, all of which affect flow rates, particle retention, and the tensile strength of the fabric.

Filter cloth serves as the fundamental component for any filter press operation, forming the initial barrier that separates solids from liquids. Maintaining porosity in filter cloth is vital for achieving high filtration rates!

For filter cloth recommendations, details regarding process changes in your operations, or reordering filter cloth, reach out to us. The dedicated teams at Micronics, including sales, engineering, and filter cloth manufacturing, are eager to utilize their expertise to meet your filter cloth requirements.

If you wish to delve deeper, visit our site for more details on filter cloth for filter press.