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Surface filtration

Woven sieve textile used by Schwegmann consist of smooth and steady (monofile) threads, which are thermofixed and therefore able to keep their typical corrugated form, even under pressure. This means that the threads stay in their position during filtration, which guarantees an definable mesh size.

First of all, the mesh size defines exactly which particles can pass the sieve textile or not:
All particles with diameters larger than the used mesh opening can´t pass the sieve textile and will be held back on its surface.

However, this effect can be influenced by different factors:

Single particles, whose size would normally allow them to pass the textile, stick together and form bridges, which are held back on the surface. These bridges form a filter cake, which can improve the filtration result considerably.

Depending on kind, quantity and arrangement of the particles (in the unfiltered liquid), the filter cake grows more or less quickly.

It could also be possible, that gelatinous particles change their shape and thereby pass a smaller mesh opening.

Furthermore the "open filter area" influences the filtration result to be achieved with a sieve textile. The open filter area defines the extent to which the filter area consists of mesh openings (in ratio to the threads of the sieve textile).

The open filter area differs a lot with regard to the different mesh openings of sieve textiles, depending on the thread diameter: while a textile with a mesh opening of 1000 µm can have an open filter area of 59% - a 25 µm - textile will have an open filter area of only about 19%, since the thread diameter is not reduced proportionally to the mesh opening. The thread would be to thin, the textile would not be stable enough.