PSU / PPSU tubes for filtration: Safe, heat and chemical resistant filtration

Traditionally known from drinking water and wastewater treatment, filtration technology is increasingly being used in various industries such as food technology. The aim of filtration is to separate substances into permeate and retentate. Depending on the type of filtration, the temperatures, pressures and substances to be filtered to which the filtration tubes are exposed vary. As a plastics processor, Ensinger offers a wide range of plastics such as PP, PE, ABS, PSU, PPSU, from which the tubes can be manufactured.

Cross-flow filtration

Cross-flow filtration is used in the chemical, pharmaceutical and food industries. The liquid to be filtered is pumped parallel to the membrane or filter medium so that the filtrate can be removed at right angles to the direction of flow. This requires pipes that either transport the filtrate (permeate pipe) or contain the membranes (housing pipe).
Due to the high flow velocity, these pipes are exposed to high pressures and mechanical loads. The component must also be resistant to temperature and chemicals, depending on the substances contained, e.g. chemicals in the suspension to be filtered or highly acidic substances. Corrosion resistance and the longest possible service life are also required. For food applications, appropriate certifications/approvals are required.

Filtration tubes made of PSU and PPSU

From Ensinger's broad plastics portfolio, the two amorphous and thermoplastic materials polyethersulphone (PSU) and polyphenylsulphone (PPSU) meet the above requirements and also offer further advantages. With a continuous temperature resistance of 170 °C (PPSU) and 160 °C (PSU), both plastics have a high thermal and good chemical resistance. Despite their low weight, PSU and PPSU have high strength, hardness and rigidity in order to withstand the high loads. In addition to these key requirements, both materials are corrosion resistant, dimensionally stable and absorb very little water.

Another advantage over stainless steel is the transparency of PSU and PPSU, which allows deposits and contamination to be detected quickly. For applications in food industry, Ensinger supplies product-specific certificates of suitability for food contact with regard to FDA approval of raw materials, compliance with Regulation 1935/2004/EU, 10/2011/EU (specific measures for plastics) and 2023/2006/EU on good manufacturing practice (GMP) for materials and articles intended to come into contact with food. 

Depending on the application, it is necessary to consider which of the two polyarylsulphones is the most suitable material. Polyphenylsulphone (PPSU) has a higher temperature resistance, higher impact strength and chemical resistance than polyethersulphone (PSU). PPSU is therefore recommended for filter systems, subject to high mechanical, thermal and chemical loads. 
Filtration tubes made of PSU and PPSU are used in reverse osmosis, nanofiltration, ultrafiltration and microfiltration applications.

Advantages of Ensinger’s filtration tubes for cross-flow filtration

Transparency

PSU and PPSU are partially transparent due to their amorphous molecular structure. This enables the rapid detection of deposits and contaminants. 

Low density

The two materials are also characterised by their low density combined with high strength, hardness and rigidity.

Viscosity

PSU and PPSU have good viscosity. They can therefore absorb deformation energy at high strength without breaking.

Creep resistance

Our PSU/PPSU filtration tubes withstand mechanical stress at consistently high temperatures.

Impact resistance

In addition, PSU and PPSU plastics can withstand impact loads such as shocks or blows without breaking.

Temperature resistance

With a continuous operating temperature of 170°C (PPSU) or 160°C (PSU), the thermoplastic tubes can withstand the high thermal loads of the filtration process. 

Chemical resistance

Even after prolonged contact with chemicals, both materials retain their physical, chemical and mechanical properties.

Water absorption

PSU and PPSU materials have very low water absorption. This makes them ideal for contact and transport of liquids. 

Dimensional stability

Polyarylether sulphones also prove their stability and high strength at high temperatures. This means that filter tubes made of PSU/PPSU can withstand the high pressures in the filter system.  

Corrosion resistance

They are also highly resistant to chemical reactions. This makes them suitable for cross-flow filtration in the chemical and pharmaceutical industries.

Sterilisability

PSU and PPSU have excellent resistance to sterilisation in the usual processes and can be reused.

Certificates

For applications in food technology, Ensinger supplies product-specific certificates of suitability for food contact with regard to FDA approval for raw materials, compliance with Regulation 1935/2004/EU, 10/2011/EU (specific measures for plastics) and 2023/2006/EU on good manufacturing practice (GMP) for materials and articles intended to come into contact with food. 

Postprocessing options

Our tubes are suitable for post-processing methods such as machining, bonding, welding, press-fitting and others.

Further product solutions made from polyarylsulfones (PSU, PPSU)

In addition to their chemical resistance and high impact strength, these two high-performance plastics offer a wide range of processing options. Products and finished parts made from PSU and PPSU can be easily machined, bonded and welded. As a plastics specialist, Ensinger covers the entire value-added chain, from compounding and the respective manufacturing process (extrusion, injection molding, 3D printing) to further processing in-house.

Ensinger has established itself as a One-Stop Shop in many industries, including the food industry. Every day, its food solutions contribute to health protection and safe nutrition worldwide.