KNOLL Maschinenbau GmbH Schwarzachstraße 20
D-88348 Bad Saulgau

Tel.+49 (0) 7581/2008-90388
Fax+49 (0) 7581/2008-90140

Contact form

Further information

Hydrostatic filter HL

Areas of application

The hydrostat filter HL is a fleece filter for cleaning cooling lubricants during material removal machining operations. It is used as an autonomous cleaning unit (e.g. during grinding), or as a supplement to chip conveying systems. The combination of vacuum technology and filter fleece reduces operating costs through low fleece consumption and reduced loss of cooling lubricants.



  • Minimum residual moisture in fleece and waste discharge, resulting in less cooling lubricant loss and redution of disposal costs
  • Low fleece consumption
  • High filter fineness
  • Trouble-free removal of chips, including light alloy
  • All-purpose filter for different machining procedures, materials and coolant lubricants



The contaminated liquid flows through the inlet box into the filter. It then runs through the filter fleece into the filter chamber. From there the filtered medium gets to the clean tank. The vacuum pump generates a partial vacuum in the filter chamber. The high pressure dierential at the filtering surface creates on the filter fleece a thick filter cake (concentrate) which itself acts as a filter medium and filters out the smallest dirt particles. As the filter cake increases in size, the flow volume through the filter surface decreases and the level of contaminated liquid rises. At the pre-defined level, the belt drive switches on and conveys the carrier belt together with the filter fleece a small distance forward. This allows clean filter fleece to reach the filter surface, the flow volume increases and the level of contaminated liquid is reduced again. Once it has emerged from the contaminated liquid, the filter fleece runs over the drying section. The air flow absorbs most of the moisture from the fleece and dirt before they reach the sludge container. A scraper is also available as an option. It scrapes most of the dirt into the sludge container and has an additional winding unit for the used fleece.

Hydrostat filter HL