Precoat filter system in a production hall

precoat filters

Filtration solutions for the treatment of coolant lubricants.

A precoat filter system for the filtration of cooling lubricants in the automotive industry
FAUDI precoat filter system

Cartridge filter systems: Precoat filters

Where is a precoat filter actually used? In the machining of metallic surfaces, cooling lubricants are used for cooling, lubrication and flushing. In order to protect the environment, the contaminated cooling lubricants, such as oils or machining emulsions, are not disposed of, but are cleaned with the help of precoat filter systems in order to make them available to the process again with an appropriate degree of purity and to integrate them into the cycle over long periods of time.
Precoat filters are often used in grinding and honing processes, in finishing, lapping, eroding, pressing and rolling as well as in ultra-fine filtration.

Precoat filter with wet discharge, Type AS

Conventional precoat filtration with wet discharge; the sludge treatment and drying takes place in secondary filters.

Precoat filter with dry discharge, Type AST

One advantage over conventional precoat filtration is the low space requirement, as no additional secondary sludge treatment is necessary. Sludge treatment and drying takes place directly in the precoat filter on the filter cartridges with subsequent dry filter cake discharge.

Electroplating precoat filter, Type ASG

Type ASG precoat filters are ideal for cleaning electroplating baths (acid baths), treatment of salt solutions, electrochemical processing and the treatment of other aggressive media as well as for ultra-fine filtration.

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  • Can be used for different
    processing methods
  • Highest possible
    filtration quality
  • Compact and durable
  • Especially economical for
    large volumetric flow rates
  • Flexible operation, adaptable to
    different operating conditions
  • Long service life
Design layout of FAUDI precoat filters - for cleaning oils or machining emulsions
Design layout FAUDI precoat filter

Design layout

Precoat filters

The precoat filter consists of the following components:

1. Filter inlet
2. Filter outlet
3. Lid lifting swivel device
4. Inspection glass
5. Intermediate plate
6. Filter cartridges
7. Clean chamber
8. Dirty chamber

3D image of a precoat filter system with FAUDI logo
3D image of a precoat filter system with FAUDI logo

how does a
precoat filter

The FAUDI precoat filter consists of a pressure vessel and is divided into a dirty and clean part by an intermediate plate in which the filter elements are installed. The dirty medium is filtered through the filter elements, whereby the flow through the filter elements is from the outside to the inside. However, before the actual filtration of the contaminated medium begins, the filter elements must be precoated with filter aid. During the so-called precoating process, the filter aid is deposited on the filter elements and forms a precoat layer, which ultimately constitutes the filtration fineness. Depending on the filter aid used and the dirt content of the medium to be filtered, filter fineness between 3 and 10 µm can be achieved. After the precoating process, the actual filtration starts automatically. When the maximum filtration time is reached, the filter elements are completely cleaned by an automatic backwash and are available for a new cycle.

Section of a FAUDI precoat filter - for cleaning oils or machining emulsions
FAUDI precoat filter rendering


The filter pump takes the dissolved mixture of filter aid and clean medium from the precoat tank and applies it to the filter cartridge. The mixture flows through the filter cartridges from the outside to the inside. This precoating process is carried out until a sufficient layer of filter aid has built up on the cartridge.


During filtration, the contaminated medium is taken from the dirt tank after the precoating process, applied to the filter elements and flows through from the outside to the inside. During the filter cycle, the dirt particles accumulate on the precoat layer.


When the maximum differential pressure between the dirty and clean sides of the filter is reached or a preset filtration time is reached, automatic regeneration or backwashing is initiated.

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Precoat filters (AS/AST/ASG)

Data and Facts


  • Filtration fineness

    Up to 3 µm

  • Fluids

    Oils, machining emulsion,
    galvanic electrolytes

  • Filter material

    FAUDI cartridges in plastic
    and stainless steel

  • Filter surface area

    1.5 – 85 m²
    (per filter dome)

Industries: Where they are used


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