KNOLL Maschinenbau GmbH Schwarzachstraße 20
D-88348 Bad Saulgau

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

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Vacuum filter VL

Areas of application

The vacuum filter VL is a high performance filter for cleaning the cooling lubricants (CL) of machining processes, in particular grinding processes. Depending on the requirement, several filter elements can also be used here for individual machines (locally) or machine groups (centrally). Its particular operating efficiency is a result of high energy efficiency, low coolant lubricant loss and low disposal costs.



  • Production of pure concentrate with low residual moisture as standard without filter aids
  • Optimised filter capacity, filter quality and energy efficiency thanks to a flawless control system
  • Continuous filter process without reverse flushing intteruption
  • Forced degasification of coolant lubricants in the filter
  • Can be used for different machining processes, materials and coolant lubricants
  • Problem-free removal of light metal chips




Filtering process
The contaminated liquid flows through the inlet box into the filter. It then runs through the filter belt into the filter chamber. From there a filter pump delivers the filtered medium to the clean tank. The vacuum pump generates a partial vacuum in the filter chamber. The high pressure differential at the filtering surface creates on the filter belt a thick filter cake (concentrate) which itself acts as a filter medium and filters out the smallest dirt particles. The filter and vacuum pumps are regulated in line with demand and provide for a settled, uniform filtering process.

Filter belt regeneration
The permeability of the filtering surface decreases as the filter cake increases. When the vacuum pump has reached its maximum output, the level of the contaminated liquid rises up to a defined maximum level. The belt drive now switches on and conveys the carrier belt together with the filter belt one stage further. This allows permeable filter belt to reach the filtering surface and the volumetric flow through the filtering surface continues to rise. The feed area varies in such a way that the set clock cycle remains constant. The endless filter belt passes through the following stations:
a) Filtering phase (filtering out of the dirt particles)
b) Drying area (removal of liquid from the concentrate)
c) Cleaning with air or brush (removal of the concentrate)
d) Reverse flushing (removal of the residual particles)

Vacuum filter VL