Filtration Expertise

Resources for your filtration requirements

Material suitability, the Pressure Equipment Directive, fluid groups, and the ABCs of plastics — our accumulated expertise, freely accessible.

The ABCs of Filtration — Plastics

Designations, abbreviations, and brand and trade names of the key plastics used for seals, filter media, and filter systems — searchable.

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Suitability of Materials for Filtration Applications

Which material is — to what extent — suitable for your application? Overview of stainless steels, plastics (seals), and fibers (filter media).

All information is provided without guarantee of accuracy or completeness. The values serve as a guide — we recommend testing under actual operating conditions; warranty claims cannot be derived from this. Please contact us for a technical review.

Stainless Steels for Filter Systems & Vessels

Chemical Resistance, Properties & Typical Applications of the 15 Most Important Materials:

1.4301 (AISI 304)

Frequently used austenitic chromium-nickel steel with numerous applications thanks to good processing properties. Acid-resistant, good corrosion resistance, very good weldability, good machinability, deep-drawable, wear-resistant, easily polishable, suitable for low temperatures.

1.4306 (AISI 304 L)

Stainless austenitic chromium-nickel steel with a relatively high chromium/nickel content; significantly more corrosion-resistant than the comparable material 1.4307. Used in plant engineering for nitric acid and other aggressive acids. High-temperature resistant, tough at low temperatures, very good forgeability and weldability, easily polishable; machinability is rather poor.

1.4313 (AISI 415)

Stainless martensitic chromium-nickel steel with very good mechanical properties, especially in high-pressure applications; suitable for turbine and power plant engineering. Moderate corrosion resistance and forgeability, good polishability.

1.4401 (AISI 316)

Stainless austenitic chromium-nickel-molybdenum steel with good corrosion resistance to acids and chloride-containing media; primary use in the food and chemical industries. Acid-resistant, cold-formable, polishable; very good corrosion resistance, good mechanical properties.

1.4404 (AISI 316 L)

Chemically resistant, stainless austenitic chromium-nickel-molybdenum steel; good resistance to acids and chloride-containing media; primary use in the food and chemical industries. Very good corrosion resistance and weldability, good forgeability and polishability.

1.4406 (AISI 316 LN)

Chemically resistant austenitic chromium-nickel-molybdenum steel; very good resistance to pitting corrosion, crevice corrosion, and general corrosion; primary use in the chemical industry and medical technology.

1.4410 (UNS S32750)

Super duplex steel (austenitic/ferritic) with high chromium, nickel, and molybdenum content; frequently used in seawater environments (offshore power plants, seawater desalination). Very good corrosion and chemical resistance, high strength, very good thermal conductivity.

1.4418 (AISI S165M)

Chemically resistant, stainless, martensitic, acid-resistant, heat-treatable chromium-nickel-molybdenum steel with very good mechanical properties; for parts of all types subject to mechanical and corrosive stress.

1.4429 (AISI 316 LN)

Chemically resistant austenitic chromium-nickel-molybdenum steel with high corrosion resistance and good mechanical properties; excellent weldability — therefore of great importance in chemical equipment and vessel construction.

1.4435 (AISI 316 L)

Stainless austenitic chromium-nickel-molybdenum steel with high corrosion resistance and good polishability; primarily used in the textile and pulp industries, and also in medical technology due to its excellent surface finish. Resistant to intergranular corrosion.

1.4462 (AISI S31803)

Alloyed duplex steel with excellent corrosion resistance; used in many areas of the offshore industry. Rust and acid-resistant; the duplex microstructure provides high strength and resistance to stress corrosion cracking.

1.4501 (AISI F55)

Corrosion-resistant super duplex steel with special additives; excellent resistance to pitting and crevice corrosion, good seawater resistance (offshore industry). Very good chemical resistance, as well as resistance to erosion.

1.4547 (AISI 254SMO)

Alloyed, chemically resistant stainless steel with special alloying elements. Austenitic, acid-resistant, good to very good resistance to pitting and stress corrosion cracking, good elongation values and weldability.

1.4563 (UNS N08028)

Alloyed, chemically resistant stainless steel with special alloying elements. Austenitic, good resistance to corrosive media.

1.4571 (AISI 316 Ti)

Alloyed, chemically resistant, austenitic chromium-nickel stainless steel with very good corrosion resistance. Good weldability, good forgeability, moderate mechanical properties.

Plastics for Seals & Filtration Systems

Which sealing material is suitable for your application (chemicals, products)? Depending on the application, E-CTFE (Halar™), ETFE, FEP, PTFE (Teflon™), PVDF, EPDM, FPM/FKM (Viton™), NBR (Perbunan®), and silicone rubber are available. Detailed chemical resistance tables (A–Z, from “alkaline exhaust gases” to “two-stroke oil”) are available upon request — the values are based on laboratory tests by raw material manufacturers and serve as a guideline.

Fibers (Filter Media)

Which fiber is suitable for your application? Resistance to the following is evaluated:

Acids
Alkalis
Solvents
Oxidizing agents
Bacteria / Mold

Typical fibers include polyester, polypropylene, polyamide (Nylon™), aramid (NOMEX®), cotton, glass fiber, and PTFE. We would be happy to discuss the appropriate fiber for your medium and temperature in a direct consultation — or you can simply specify your medium in the checklist.

Pressure Equipment Directive (PED), Hazards & Fluid Groups

Official Designation & Scope of Application

Directive 2014/68/EU of the European Parliament and of the Council of 15 May 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of pressure equipment (recast). The Directive entered into force in July 2014, has been applicable since 19 July 2016, and replaced the previous Pressure Equipment Directive 97/23/EC.

The PED applies to the manufacture, design, and conformity assessment of assemblies and pressure equipment with a pressure greater than 0.5 bar. Pressure equipment includes pressure vessels, steam boilers, piping, safety accessories, and pressure accessories.

Essential Safety Requirements (Annex I PED)

General: Pressure equipment must be designed, manufactured, checked, and, where appropriate, equipped and installed in such a way as to ensure its safety when put into service in accordance with the manufacturer's instructions or under reasonably foreseeable conditions of use.
Design: Sound design taking into account all safety-critical factors throughout the entire service life — with appropriate safety factors and margins for all relevant failure modes.
Manufacturing: The manufacturer ensures the proper implementation of the measures defined in the design phase using appropriate techniques and procedures.
Materials: The materials used, if they are not to be replaced, must be suitable for the entire intended service life.
Further specific requirements for certain pressure equipment.

Hazards & Fluid Groups

The fluid is the determining factor for classification under the PED — gases, liquids, or vapours in pure phase as well as their mixtures:

Fluid Group 1

Hazardous Fluids

Media with hazard characteristics according to GefStoffV: corrosive, flammable, explosive, extremely flammable, unstable, highly flammable, organic peroxide, oxidizing, pyrophoric, self-reactive, toxic.

Fluid Group 2

Non-Hazardous Fluids

All media without the hazard characteristics of Fluid Group 1 — e.g., water, many foodstuffs, and non-critical process media.

Categorization of Pressure Vessels

Pressure equipment for filtration technology in Fluid Groups 1 or 2 is classified according to Art. 4(3) PED ("Sound Engineering Practice") or according to Category I, II, III or IV (with CE marking) as per Annex II of the PED — depending on fluid group, pressure, and volume. Conformity assessment is carried out in accordance with the relevant required modules, ensuring compliance with the safety requirements of the AD 2000 Code.

In our quotation checklists, we ask directly for the fluid group and PED classification — if the classification is not yet known, we will carry out the assessment as part of the design process.