Filter Press Cloth – Everything You Need to Know

What is a Filter Press Cloth?

A filter press cloth is a type of material used in dewatering applications.

The process of dewatering is to separate the liquids from solids through a pressure filter, which pushes the liquid through the cloth.

The filter press is the machine where the filter cloths are installed in ‘series’. The liquid and slurry are fed into the filter press machine and are then ‘pressed’, meaning that it is squeezed to force the separation between the two elemental states. The process occurs by the filter press squeezing the filter cloth from both sides, forcing the material through the cloth and ‘filtering’ in the process.

What are Filter Press Cloths Used For?

Filter press machines are used solely for the separation of liquids from solids. The filter cloth is usually made to measure, depending on the filter press machine plate width, and is usually measured in meters.

Depending on the micron requirements, the particulate (particle size being pressed) can vary within the weave of the filter cloth. The usual range of microns for a filter cloth membrane varies between 5 to 25 microns.

What Materials are Filter Press Cloths Used From?

The cloth material from which the filter cloth is made also varies to suit the particular plate it uses—these range from full membrane to centre-fed, gasketed to non-gasketed.

Filter press cloth manufacturers will typically use polyester thread for the filter cloth material. However, filter cloths are commonly known to be made from polypropylene, cotton, nylon or felt. These are high-temperature, durable cloth materials that can be used in various extreme temperatures.

The filter cloths are manufactured in Mono and Multi Filament to ensure a high-quality finish, strength, chemical resistance, abrasion and long lifespan.

Mono-Filament Cloth

For mono-filament filter cloth, the woven fibres are singular. Meaning there is a single-line weave. This allows for fantastic cake release and resistance. There is lower particle retention compared to muli-filament fibres. The material is naturally super-strong.

Multi-filament Cloth

Multi-filament cloth describes a varying size of fibres used within the thread of the cloth, which is grouped in one line. Compared with this type of cloth, there is better micron retention than mono-filament cloth.

Gasketed or Non-Gasketed Filter Cloth?

Gasketed/Caulked/Recessed Filter Plates

Depending on the requirement of your filter plate, your filter press cloth will come in differentiating shapes, sizes and even materials. This is often due to the filter press plate. The ‘gasket’ or ‘caulked’ filter plate is the most commonly used filter press plate. Also referred to as a ‘recessed chamber’ filter plate, these particular ones are the most commonly used of all filter plates within liquid-from-solid separation.

Gasketed filter plates are expected to perform to a standard where there is no leakage from the filter cloth through the filter plate. The filter cloths used are typically hexagonal, with a sewn cord to ensure any microns passed through are caught within the filter press cloth.

Non-Gasketed Filter Plates

For Non-gasketed filter plates, the filter press cloth is lighter and less robust but easier to install. This type of filter cloth can incur some leakage from the filter plate.

The Weave of the Filter Press Cloth Helps the Performance

Weave patterns for a filter press machine cloth depend on your goal.

Five specific filter cloth weave types are used. These are:

Leno Weave

The Leno Weave is constructed with two or more warp threads that cross over each other and are then interlocked with multiple filling thread lines. You can occasionally use one filling thread depending on your requirement from the Leno Weave.

This weave is lightweight and should be used in lighter cake release filter presses.

The Twill Weave

The Twill Weave is a standard weaving process for fibres and is used across all manufacturing processes that require weaving.

In a Twill Weave, the twill line crosses over at least two consecutive rib lines and is moderate in binding. The resistance on this weave is larger than that of the Leno weave so a heavier cake release can be used on this type of cloth weave.

The Plain Weave

The Plain Weave is another type of weave that is used across multiple manufacturing specialisms. It is also the simplest weave of all weave patterns.

This article weave has high particle retention, with moderate cake release properties, whilst also being rather robust. This weave is perfect for moderate cake release and high requirements for particle retention from the filter press.

The Basket Weave

A variation of the Plain Weave, the Basket Weave, whereby at least warp yarns cross alternately with two or more filling yarns.

This is a looser weave, so it is only recommended on basic-level filtering requirements due to its lack of stability.

The Satin Weave

Arguably the most complicated weaving pattern for filter cloths, the Satin Weave shows a repetition of crosses between the ‘warp’ and ‘filling’ floats. Throughout the weave, the weft thread will cross over at least three lines of warp threads before going under one, back over a further three, and so on.

This particular weave is required where a good solid cake release is required.

Cleaning Your Filter Press Cloth

When the filter cake is no longer dry and has a slimier texture, this is the time to clean your filter (unless the cloth has already been cleaned. In which case, you should replace the filter cloth).

Should the filter cloth require cleaning, the cleaning process differs depending on the filter plate you use.

For Gasketed filter cloth cleaning, you can use an acid-washing method. This specific cleaning method should be followed meticulously to ensure safety and proper cleaning. It is not a cleaning method for Non-Gasketed filter cloth due to the NGC plate’s characteristic of ‘leakage’.

For NGC plates, you should consider the Cold Water Spray cleaning method.

For the Cold Water Spraying method, the cloth should be washed at a high-pressure (between 800-1200 PST) within the cold water spray unit.

This method flushes the cloth surface and penetrates through the cloth to flush out any particles sitting within the cloth.

Working with Filter Press Cloth Manufacturers

When searching for the right filter cloth manufacturer, you should consider a few things.

You must ensure you’re fully prepared with the requirements of your filtration needs. It’s key to understand the purpose of your filtering requirements, the machine your user needs and the area in which your filter machine operates. You also need to know the cake release you’re looking for and the mircon amount your filter machine will need.

Once you have this information, you should then expect the filtration expert to be able to provide the necessary solution information to fit your requirements. The filtration expert should be able to assess your requirements and the correct consultancy for the most effective filtration solution for your press machine.

A quality filter cloth manufacturer will naturally collaborate with you as the expert to ensure the best solution fits the business need and provides the most effective filtering solution.