Select Proper Filter Fabric - M.W. Watermark

FILTER CLOTH SELECTION

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Determining the proper cloth construction requires knowledge of the slurry characteristics and the filtration requirements. Below are some of the factors we consider in the filter cloth selection process.

Contact M.W. Watermark to learn more about how to identify or measure these variables.

• Is the cake or the filtrate a product?
• pH?
• Slurry temperature?
• Slurry particle size?
• Is the slurry preconditioned (Polymer, DE, Ferric, Lime, etc.)?
• Abrasive, coarse particles?
• Existence of solvents, oils or greases?
• Number of filtration cycles per day?

The above data helps in determining the following:

• Fabric raw materials / compatibilities
• Type of yarn (fibers)
• Fabric weave
• The type of fabric finishing needed to produce the best filter cloth for the application

Common filter cloth materials

Polypropylene

Polypropylene is the standard for filter cloths and performs ideally in most applications. This material can withstand higher temperatures, does not easily succumb to blinding (clogging of the weave) and has a smooth surface which aids in cake removal. However, it’s important to know the make-up of the slurry before assuming that polypropylene is the material of choice.  For example, if the slurry is bleach, polypropylene will not be compatible, and polyester filter cloth materials must be used.  Latex borders can be applied to a non-gasketed cloth to provide a better seal under pressure.

Nylon

This durable fiber is often chosen for its long life in the face of abrasives. Though higher in cost, nylon blends offer such durability that the higher cost can be justified by longer service life.

Polyester

Often chosen when sustained operating temperatures are over 180 degrees, or when oxidizing agents are present. 

FILTER CLOTH FIBER TYPES

Filter cloths are manufactured using synthetic fibers.

• Monofilament: Single, smooth, continuous extrusion. Highest flow rates, good resistance to blinding, good abrasion and scaling resistance. Fibers are typically between 4 mil and 10 mil (.004″ to .01″) in diameter. Best cake release.

• Multifilament: Multiple continuous fibers twisted together to form one yarn. Excellent retention for smaller particles. Good cake release.

• Staple (Spun): Short lengths of fibers (similar in appearance to cotton) spun into a yarn. Tends to have a “hairy” appearance. Best solids retention. Poorest cake release.

FILTER CLOTH FABRIC WEAVES

• Satin: Satin Weave (or Sateen Weave) has a smooth surface caused by carrying the warp yarn on the fabric surface over many weft yarns. Intersections between warp and weft are kept to a minimum. Very flexible, easily conforms to most curved surfaces. Satin weave is popular for its excellent cake release and resistance to blinding. Particle retention is average.

• Twill:  Twill Weave adds a diagonal rib or “twill” line into the weave, adding strength at the expense of some stability. These diagonals are caused by moving the yarn intersection one weft thread higher on successive warp yarns. Cake release is average. Average resistance to blinding.

• Plain: Plain Weave (or Checkerboard Weave) is the most basic weave, with a weft thread alternately going over one warp thread and then under one warp thread. Average in strength, cake release, and stability. High particle retention and low resistance to blinding.

ADDITIONAL WEAVE PATTERNS

• Leno Weave: The leno weave involves two or more warp threads crossing over each other and interlacing with one or more filling threads. This is known as a “locking” weave, as it is mainly used to prevent the shifting of fibers in open weave fabrics. This type of weave is usually only found in backing cloths.

• Basket Weave: Basket weave is a variation of the plain weave. Two or more warp yarns alternately cross with two or more filling yarns. Stronger than a plain weave, at the expense of stability. Typically used for backing cloth or basic applications requiring additional strength.

FABRIC FINISHING

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

• Singeing: Removal of fibers on the surface of staple and felt fabrics to enhance cake release.
• Calendaring: With use of heated compression rolls, the fabric is “melted” to adjust the permeability and provide a smoother surface for cake release.
• Heat Setting: Through a wet or dry process to create a dimensional stable fabric that will not shrink, stretch, etc.

Contact M.W. Watermark to discuss your particular application.

Filter press cloth is designed for filter press filters. The filter plates and filter frames are arranged alternately, and the filter cloth is overlaid on both sides of the filter plates. It is mainly used in sludge dewatering, chemical, mining, food and other industries.

The main materials used for filter press cloth are polypropylene (PP), polyester (PET), and polyamide (PA), each offering different filtration performances:

1. Polyamide material is resistant to acids but not alkalis, has higher strength compared to other materials, has good abrasion resistance, it has excellent abrasion resistance properties.

2. Polyester material is resistant to acids and weak alkalis, with strength and abrasion resistance ranking just below nylon. It has good heat resistance and higher chemical stability but is susceptible to hydrolysis in strong alkalis.

Polypropylene material has strong acid and alkali resistance, excellent strength and abrasion resistance, and good chemical stability.

Filter Press Cloths Material and Specifications

Material

Weight

（±5%）

Air Permeability（L/㎡ S±20%）

Thicknes

（mm±10%）

Polypropylene

310

160

0.49

Polypropylene

800

300

3

Polypropylene

640

100

1.15

Polypropylene monofilament

380

80

0.63

Polypropylene monofilament

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400

50

0.61

Polypropylene multifilament

680

38

1.28

Polypropylene multifilament

625

15-20

1.1

Polyester staple fiber

340

35

0.65

Polyester staple fiber

520

15

0.9

Polyester staple fiber

700

0-3

0.63

Polyester staple fiber

250

15

0.6

Polyamide multifilament

283

0.55

Polyamide monofilament Multifilament

700

200

1

Polyamide monofilament

670

300-400

1.16

Polyamidemonofilament

450

0.55

Different materials and models of press filter cloths vary in air permeability, pore size, thickness, and weight. If you have any doubts about selecting the right model for your filter press, it is recommended to consult a reputable filter cloth manufacturer.

Bolian has extensive experience in producing filter press cloths, and provides customers with various choices including different types and dimensions. We develop and manufacture customized filter cloths according to different working conditions. Bolian filter press cloth is designed to meet filtration needs, including materials, yarn types, weaving processes, and surface treatments.

Bolian provides various filter press cloth products including the barrel neck, hanging, and recessed types. We offer a wide range of filter press cloth with different air permeability based on specific filtration requirements. We provide customized filtration solutions with the support from technical consultancy, design, manufacturing to installation.

Want more information on filter press manufacturer? Feel free to contact us.