Typical tasks in liquid filtration

The filtration of liquids fulfills different tasks in industrial processes, which are often combined:

• Separation of solid particles from process media

• Protection of pumps, valves and control elements

• Ensuring consistent product or process quality

• Reduction of wear and tear and downtimes

• Retention or recovery of valuable components

Depending on the application, the focus is on different criteria. While in some processes the focus is on the finest possible separation, in other cases low pressure losses or long service lives are crucial. Cleanability and reusability of the filter elements also often play an important role.

Requirements for porous filter materials

Porous filters used in liquid filtration must fulfill several basic requirements. These result from both the physical properties of the liquid and the respective operating conditions.

Mechanical load capacity

Filter elements are permanently or cyclically exposed to differential pressure during operation. The porous structure must remain dimensionally stable and must not become compressed or deformed even under changing loads. An even distribution of pores makes a significant contribution to avoiding local overloads.

Chemical resistance

Liquid media can be neutral, oily or chemically aggressive. The material used must be resistant to the medium without causing corrosion, swelling or changes to the pore structure. Chemical resistance is therefore a key selection criterion.

Defined pore structure

Homogeneous porosity is a prerequisite for reproducible filtration results. Non-uniformities in the pore structure lead to preferred flow paths, increased wear and shortened service life. Porous sintered materials enable precise adjustment of the pore structure across the entire cross-section.

Cleanability and service life

In many applications, filter elements are cleaned and reused several times. The pore structure must be designed in such a way that deposited particles can be removed mechanically or chemically without permanently impairing the filter function.

Suitable SIPERM® materials for the filtration of liquids

The selection of a suitable SIPERM® material for liquid filtration is based less on general material properties and more on the filtration behavior in the liquid medium. The decisive factors here are flow rate, pressure loss, separation behavior and the possibility of cleaning under process conditions.

SIPERM® R – porous stainless steel in liquid filtration

SIPERM® R is used in liquid filtration where stable separation limits and high mechanical loads are required. The porous stainless steel structure enables a uniform flow even at higher differential pressures and is suitable for applications with continuous operation.

A major advantage lies in the cleanability: filter elements made of SIPERM® R can be cleaned mechanically or chemically without significantly changing the pore structure. This means that constant filtration properties can be achieved over several cleaning cycles. SIPERM® R is therefore often used where a reusable filter solution is required.

SIPERM® B – porous bronze for low pressure loss filtration

SIPERM®-B is the preferred choice for liquid filtration when low pressure losses are a priority. The homogeneous pore structure ensures a uniform flow through the filter surface and reduces local load peaks.

Typical applications include oil-containing or lubricant-carrying liquids where stable filtration is required without a significant increase in pressure. SIPERM® B is particularly suitable for filtration tasks where long service life and uniform flow behavior are crucial.

SIPERM® HP – porous polyethylene in liquid media

SIPERM® HP is used in liquid filtration when chemical resistance and media-adapted wetting behavior are the primary requirements. For aqueous media, the material can be made hydrophilic to ensure a uniform flow and avoid air inclusions in the pore structure.

In the filtration of liquids, SIPERM® HP is particularly suitable for applications with moderate temperatures where metallic materials are not required. The adjustable porosity enables targeted adaptation to the desired separation efficiency.

Typical designs in liquid filtration

SIPERM® materials can be manufactured in different geometries in order to adapt them optimally to the respective application. The design influences both the filtration performance and the integration into existing systems.

• Filter cartridges and filter tubes for continuous filtration processes with a defined flow rate

• Plates and discs for flat filtration tasks or as installations in housings

• Molded parts for integration into compact assemblies with specific connection geometries

• Welded constructions for the realization of larger filter surfaces or individual installation situations

The design is selected depending on the flow rate, available installation space, maintenance concept and cleaning method.