Polypropylene Filter Discs for Nutsche and Disc Filters

A textile insert for a filter surface you already have

A filter disc is not a filter unit. It is the textile separating layer that sits on a supported filter surface you already have: the plate of a nutsche filter, the segment of a disc filter, a perforated support, a strainer plate.

That also settles what this page does not sell. WINKLER supplies nutsche filter cloth and disc filter cloth, not the nutsche and not the disc filter. If you are looking for a rotary disc filter, a vacuum disc filter or a complete cloth disc filter unit, you are looking for a machine, and this is the consumable that goes into one.

Three things decide the selection, in this order: does the geometry fit, does the grade fit, does the material suit the medium.

Geometry first: outer diameter, inner diameter and the seating face

Most wrong orders for round filter media start with the geometry, and usually with the inner diameter.

The outer diameter has to match the filter surface without overhanging the sealing edge. The inner diameter has to match the central opening, which is normally the outlet spigot or the shaft. Only both together give you the usable filter area.

The right-hand column is calculated from the diameters and describes the plain annular area. Between the smallest and the largest standard size that is roughly a factor of seven, while the outer diameter only about triples. If you select by diameter alone, it is easy to underestimate the difference.

What the arithmetic does not show: the area actually flowed through is smaller, because part of the disc rests on the sealing edge and on support ribs. For sizing, the seating situation in your plant matters more than the annular area on its own.

Filter disc in 10, 40 or 100 micron

All five standard sizes come in three grades. The figures come from the fabric supplier and describe the filter medium, not the result of your filtration.

A 10 micron disc is therefore not simply the better choice. With a suspension that builds a load-bearing cake quickly, a 100 micron filter disc can give the better overall result, because the cake takes over the fine work and the surface stays permeable for longer.

The same applies as everywhere in this range: the number describes the medium. What is actually retained also depends on particle shape, particle distribution, differential pressure, the way the disc is seated and how the cake builds.

Polypropylene filter discs and what the material can be asked to do

The polypropylene filter discs, also called filter cloth discs or textile filter discs depending on the plant, are a longer-lasting alternative to the paper inserts many units still run. A PP fabric does not tear on removal, deforms less under differential pressure and can be used more than once in many processes.

Polypropylene resists a wide range of aqueous and industrial media. Whether it suits yours depends on composition, concentration, temperature and contact time. We do not give a blanket resistance statement; for media that are not clear-cut we check the case before you order.

On reuse: PP filter discs are suitable for it in principle, but how often is a question of the process. Before every further use, check the fabric, the contour and the edge zone for damage, deformation and blinded areas. We deliberately do not quote a number of cycles or a general cleaning procedure.

One point on the term. mesh filter disc and synthetic filter discs are used in the market for wire mesh, nylon and laboratory products as well. What is offered here is a woven polypropylene disc for industrial use. Metal, wire mesh and ceramic discs are a different product type with a different manufacturing route, and they are not part of this range.

Nutsche filter cloth and disc filter cloth: the same disc, two plant types

Both plant types work with a supported filter surface, but they are built differently.

In a nutsche filter the disc sits on a screen base or a perforated plate, and the liquid is drawn or pushed through by vacuum or pressure. A nutsche filter disc is exactly that part. The German word Nutsche has carried over into English engineering usage unchanged, which is why the trade term here is nutsche filter cloth and not funnel filter paper. A Büchner funnel is a laboratory item and a different thing.

In a disc filter, several filter surfaces sit as discs or segments on a common shaft. Filter cloth for a nutsche filter and filter discs for disc filters are the same product; what differs is the geometry of the actual surface.

What cannot be claimed is general suitability for every design. Vacuum and pressure nutsche filters, closed systems and special builds place different demands on edge sealing, differential pressure and handling. Agitated nutsche filters and ANFD units in particular have their own geometry and sealing concept, and we check those individually rather than confirming them in advance.

Custom filter discs, centre holes and laser-cut contours

If no standard size fits, we make to measure. With this product that is closer to the rule than the exception, because older plant and special machines rarely have catalogue dimensions.

For custom filter discs a sketch with the outer and inner diameter, the grade and the quantity is usually enough. A custom diameter filter disc can equally be made from a sample disc you send in.

Cutting runs on our laser systems. That means a filter disc with centre hole is only the simplest case: additional holes, slots, elongated cut-outs, segments and free contours are possible as well, as far as material and geometry allow. Laser cut filter discs and filter discs as a one-off special leave the same machine.

On the cut edge: laser cutting thermoplastic fabric stabilises the edge thermally, which reduces fraying considerably. How much depends on the material and the geometry.

Technical data

Frequently asked questions about filter discs

The questions we get concern measuring, grade selection, reuse and special shapes.

How do I measure a filter disc correctly?

You need the outer diameter and the inner diameter. Record the seating and sealing face as well, plus any further openings, slots or cut-outs. A sample disc or a dimensioned sketch cuts the risk of error the most.

Which grade should I choose?

10 micron for fine retention, 100 micron for quick drainage, 40 micron as the middle way. With suspensions that build a load-bearing cake quickly, the more open version is often the better overall answer. For critical separations, a trial on the real medium tells you more than the number does.

Can filter discs be cleaned and reused?

In principle yes, and how often depends on the process. Check fabric, contour and edge zone for damage, deformation and blinded areas before every further use. We do not set a fixed number of cycles or a general cleaning method, because both depend on the medium, the solids and the way the disc is handled.

Are the discs suitable for my nutsche filter?

Confirmed is their use as a textile insert in nutsche filters and disc filters. There is no blanket release for every design, because edge sealing, differential pressure and handling differ. For pressure nutsche filters and agitated units we check the case rather than assume it.

Does a precise cut prevent bypass flow?

A well-fitting cut can reduce the risk. It cannot rule it out on its own: the filter plate, the clamping, the sealing faces, the support, the differential pressure and the assembly all have a part in it.

Which special shapes are possible?

Besides other diameters, holes, slots, elongated cut-outs, segments and free contours are possible in principle. Feasibility, tolerance and material behaviour are checked per project.

How many discs are in a pack?

The standard variants are supplied in packs of ten. For custom production the quantity follows your requirement.

Do you supply metal or ceramic filter discs?

No. This range covers textile filter discs in polypropylene. Metal, wire mesh and ceramic discs are a different product type with a different manufacturing route.

Do you supply the disc filter or the nutsche filter itself?

No. WINKLER makes the filter media that go into an existing unit. A disc filter, a rotary disc filter, a vacuum disc filter or a complete cloth disc filter installation comes from the plant manufacturer; the discs that run in it can come from us.