Filter Press Cloth 7L: the standard grade for processes that already run

What a standard filter press cloth is actually for

Not every process needs a special grade. A large share of chamber filter presses run on a suspension that has behaved the same way for years, with a filtrate quality that is good enough and cycle times that fit the shift.

That is what the 7L is for. It is a multifilament cloth at 25 micron nominal and the lowest priced grade we stock. As a replacement filter press cloth it is the usual starting point when an existing cloth is swapped on schedule and the process is meant to stay exactly as it is.

It is expressly not a universal cloth. If fine solids are getting through, the 6L or the 3L is the direction to move in. If throughput is the bottleneck, the 15L is worth a look, and it carries the same nominal rating.

Which figures for the 7L are confirmed, and which are not

Here we do something unusual on a product page. We name the gap.

There is no complete technical datasheet for the 7L. Confirmed are the nominal rating of 25 micron, the multifilament construction and an existing conformity and migration document under EU regulation 10/2011. Fabric weight, thickness, weave, thread count and air permeability are not available as released figures.

So you will not find a table of six numbers on this page. Figures we cannot evidence do not get written down. If your sizing needs a specific value, ask for it and we will clarify it with the supplier and come back to you with the answer.

The EU 10/2011 documentation

For the 7L there is a conformity and migration document under EU regulation 10/2011. That regulation covers plastic materials and articles intended to come into contact with food.

Within this range it is unique to this grade, and in processes with a food-adjacent requirement it can be the deciding factor.

It is not a release for your application. Whether the document covers your specific requirement depends on the medium, the type of contact, the temperature and the rules that apply in your plant. Ask for the document and have it checked against your own specification.

The 7L in process water and industrial wastewater

Chamber filter presses running this grade work mostly on aqueous suspensions: process water carrying solids, rinse and wash waters, mineral sludges, residues from metalworking.

A process water filter press cloth does not have to be especially fine. It has to match the solid. With an evenly distributed, well flocculating suspension a load-bearing cake forms quickly and does the actual separation work; the fabric then mainly has to hold it and let liquid through.

Two things belong with that. Polypropylene stands up to many aqueous media but not to all of them, and concentration, temperature, pH and any solvents decide the case. And filtrate from a filter press cloth for wastewater is not automatically fit for discharge. What happens to it next follows from your permit, not from the filtration.

Confirmed data for the 7L filter press cloth

Fabric weight, thickness, weave, thread count and air permeability are not available as released values for this grade and are therefore not stated.

7L or 15L: same number, different evidence

Both grades are listed at 25 micron nominal. That is why they get mixed up, and it is at the same time the least informative thing they have in common.

If the 7L gives you a stable filtrate and predictable cycles, there is no reason to change. The 15L becomes interesting when throughput turns into the bottleneck or the cake stops coming away cleanly.

Common questions about the 7L filter cloth

The questions here are about the standard role, the missing data and the comparison with the 15L.

What is the standard filter press cloth meant for?

For predictable direct filtration processes without an unusual fineness or throughput requirement, and as a replacement for an existing cloth in the same role.

Why are there fewer technical values on this page than on the others?

Because no complete datasheet exists for this grade. We only publish figures we can evidence. If you need a particular value for your sizing, we will clarify it with the supplier.

What does the EU 10/2011 documentation mean?

The regulation covers plastics intended for food contact. For the 7L a conformity and migration document exists and we supply it on request. Whether it covers your requirement has to be checked case by case.

What is the difference from the 15L?

Both carry 25 micron nominal. The 15L has a documented mono and multifilament construction in plain weave at 320 ± 40 g/m² with an air permeability of 15 ± 6 l·dm⁻²·min⁻¹. Those figures do not exist for the 7L. A change is worth considering mainly when throughput is the problem.

Is the cloth suitable for process water and industrial wastewater?

Those media are the usual field of use. Suitability depends on the type of solid, the concentration, pH, temperature and any additives. Filtrate is not automatically fit for discharge after filtration.

Can I order the 7L as a replacement for my existing cloth?

As a rule yes, provided the plate size, the inlet and the edge finish match. The safest route is to send us the old cloth cleaned, or photographs with dimensions.

Are head and end cloths available in this grade?

Yes, as in all five grades. We need the plate size, the position in the plate pack, the inlet, the edge and the fixing method.