Rotary pressure filter (RPF)

High process versatility in filtration technology

RPF X16 rotary pressure filter with TwinDrive
RPF X16 rotary pressure filter with TwinDrive

The BHS Rotary Pressure Filter (type RPF) is a continuously operating filter for pressure filtration. It facilitates gas-tight cake handling in a series of separate process steps. Cake discharge can take place at atmospheric pressure.

The rotary pressure filter supports a broad range of process steps during a single rotation of the drum. Further processes can be carried out after separating the slurry into filtrate and filter cake:

  • Single- or multi-stage cake washing
  • Displacement washing, counter-current washing, closed-cycle washing
  • Reslurrying
  • Solvent exchange
  • Steaming, extraction
  • Mechanical or thermal cake dehumidification

All process steps are performed within the filter’s segregated segment zones. This makes it possible to separately discharge the filtrates or other substances.

The rotary pressure filter is a fully encapsulated unit that can be integrated into production processes in a gas-tight manner. This means that the rotary pressure filter is also suitable for use in operating scenarios with increased safety or hygienic requirements.

The rotary pressure filter operates at a pressure of up to 7 bar (g) and within a temperature range of approx. -20° to approx. 160° Celsius. Pressure is generated hydraulically rather than pneumatically by means of gas stratification during all process steps. This enables individual optimization of each and every process step.

Each process step is sealed off into a segment zone by means of pressure-tight separation elements inside of the rotary pressure filter. The cake can be discharged to the surrounding area at atmospheric pressure.

The BHS Rotary Pressure Filter represents an improvement on the FEST filter described in the technical literature, which was invented by Dr. Fest at BHS in the 1950s.

Illustration of the individual process steps in the rotary pressure filter

Phase 1: Suspension feed and filtration
Phase 1: Suspension feed and filtration
Phase 2: Cake washing
Phase 2: Cake washing
Phase 3: Cake drying
Phase 3: Cake drying
Phase 4: Cake discharge
Phase 4: Cake discharge

Production of high-quality pearlescent pigments with the rotary pressure filter (RPF)


Rotary pressure filters from BHS-Sonthofen have proven themselves in many applications. For example, Merck uses them around the clock to produce pearlescent pigments. Watch the video to find out how BHS filtration solutions give cars and cosmetics a shiny appearance.

Fully automatic cleaning-in-place (CIP)

Watch the video to learn more about the innovative CIP technology of the rotary pressure filter (RPF) developed specifically for the pharmaceutical and food industries.

Operating criteria

The BHS rotary pressure filter is based on the principle of cake filtration and can meet the following operating criteria:

Operating method continuous
Operating pressure up to 7 bar (g)
Operating temperature up to 160°C
Solids content (suspension) up to 60% (by weight)
Cake thickness up to 175 mm
Grain size 10 - 500 μm
Filter output - suspension up to 15 m³/m² h
Filter output - dry solids up to 15,000 kg/m² h
Active filter surface 0.12 - 8.6 m²
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Brochure “Rotary pressure filter (RPF)” (PDF / 2.4 MB)
Brochure “Rotary pressure filter (RPF)”

Product brochure for the rotary pressure filter (RPF)

Size: 2.4 MB
Technical data sheet “Rotary pressure filter (RPF)” (PDF / 94 KB)
Technical data sheet “Rotary pressure filter (RPF)”

Technical data for rotary pressure filter (RPF)

Size: 94 KB
Filtration application questionnaire (PDF / 129 KB)
Filtration application questionnaire

The PDF form includes a questionnaire that asks for information we require to assess your filtration challenge. The information you provide allows us to plan industrial-scale filters and prepare lab trials, if applicable.

Size: 129 KB


  • Continuous, fully automatic operation
  • Self-contained, gas-tight operation
  • Several successive process steps are possible
  • Hydraulic pressure generation
  • High process versatility
  • Extensive application expertise
  • Suitable for suspensions containing solvents
  • Excellent workplace hygiene and safety

BHS filtration technical center

Link to tests at BHS technical center

Technical article

Continuous Pressure And Vacuum Filtration Technologies as Alternatives to Batch Filtration Operations

Chemical Industry Digest
Sept 2017
September 2017
PDF (1.8 MB)
Continuous Pressure And Vacuum Filtration Technologies as Alternatives to Batch Filtration Operations

This paper discusses the selection of the filtration process systems: continuous pressure and/ vacuum filtration through a process of laboratory and pilot testing. These tests enable problem analysis, technology selection and scale up which help in optimum filter selection.

Size: 1.8 MB

Choosing a Fine-Particle Filtration System

Chemical Engineering Progress (CEP)
December 2014
December 2014
PDF (4.4 MB)
Choosing a Fine-Particle Filtration System

Filtration technology has advanced to meet the demand to remove small particles at low concentrations. When designed ocrrectly, a candle filter or a pressure plate filter may be a more-efficient replacement for a traditional filtration scheme.

Size: 4.4 MB

Framework for Selecting Solid-Liquid Filtration Technologies for Particle Fines Removal

Chemical Industry Digest
April 2014
April 2014
PDF (2.6 MB)
Framework for Selecting Solid-Liquid Filtration Technologies for Particle Fines Removal

In the manufacturing of chemicals, petrochemicals, pharmaceuticals, etc., after the initial mixing-reactions, there is always the necessity to remove the mother liquor from the process slurry. In some cases, the liquid is the valuable component, some cases it is the solids and in other cases it is both compounds. The nature of the requirements determines the type of equipment needed for the separation process. This paper provides an overview of separation equipment and then continues with a detailed view of technologies that can remove – recover small particle fines.

Size: 2.6 MB
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