PTFE in hose systems for the chemical, pharmaceutical and food industry Markert Marsoflex PTFE hose assemblies: Innovation through years of research and development2 Table of contents 1. The material PTFE 2. Production of PTFE hoses 3. PTFE coextruded 4. PTFE in comparison 5. Requirement for PTFE 5.1 FDA approval 5.2 USP Class VI 5.3 Freedom from GMO/BSE/TSE 5.4 Regenerate-free 5.5 Virginity/Conductivity 6. Technical properties of PTFE 7. Connection of the hose fitting 8. Selection of the hose cover 9. The PTFE liner in detail 10. Which hose for which application 11. What can happen 12. Sustainability 13. Why Markert Marsoflex 14. Contact3 1. The material PTFE The four letters PTFE stand for polytetrafluoroethylene, which was originally also known under the trade name "Teflon" from the DuPont company. PTFE is a partially crystalline polymer of fluorine and carbon. PTFE was discovered in 1938 by chemist Roy Plunkett when he experimented with tetrafluoroethylene (TFE) and converted it to "colorless crumbs" polymerized. In the meantime, PTFE has become indispensable in many applications because of its outstanding properties: – PTFE is very inert and therefore has a very high resistance to almost all bases, alcohols, benzines, oils. – PTFE has a very low coefficient of friction and is therefore an ideal lubricant. – PTFE has an extremely low surface tension, so it is almost impossible to wet. There are almost no materials that stick to PTFE - also known as the non-stick effect of PTFE. – PTFE has a high temperature resistance up to +260 °C. – PTFE has very low electrical conductivity and therefore good insulation properties. PTFE has clear advantages over almost all other plastics and is the best technical solution for many applications.4 PTFE comes in two types: – Modified PTFE (modified) In – Non-modified PTFE (non modified) modified PTFE, perfluoropropyl vinyl ether (PPVE) is added. Hereby, the properties such as lower deformation, lower porosity, higher elongation at break and lower permeation are optimized. Markert uses only modified PTFE. 2. The production of PTFE hoses Polymerization produces a white PTFE powder. This produces the raw material for the manufacture of PTFE products. Market leaders in the production of PTFE include DuPont (now Chemours), DOW (3M™ Dyneon™) and Daikin. The PTFE powder is mixed with a binder (e.g. ISOPAR) for further processing and thus becomes processable. In the production of PTFE hoses, the resulting emulsion is thermally heated in an extruder and pressed over a die. If the PTFE is to be conductive, carbon is added to the PTFE in the mixing process (this is the starting material for the so-called "black" PTFE). By means of extrusion, the PTFE emulsion is sintered to the desired shape. In the final cooling and cutting process, the final PTFE hose liner is produced. ProcessFlow ExtrusionControlsControls Tube greenstate Coiling Evaporation Cooling Sintering5 The extrusion process is extremely complex, as only balanced tempering phases can ensure complete polymerization of the PTFE powder. Furthermore, the die and the PTFE guide must be matched to each other with high precision; only in this way PTFE liners can be produced reliable. The smallest inclusions or tolerance deviations in the PTFE liner can drastically influence the strength. Only raw materials of the highest quality may be used for industrial hose lines. Therefore, only the PTFE compound Teflon T-62 (Chemours formerly Dupont) is used for Markert Marsoflex hoses. 3. PTFE coextruded Pure PTFE is referred to as virgin PTFE. This PTFE forms tight linkage chains and has a very dense and thus smooth surface structure. White materials are often required, especially in pharmaceutical applications. For this purpose, pigments are added to PTFE to produce pure white PTFE. The pigmentation slightly changes the material structure, which is why unpigmented PTFE has fewer pores in the surface than pigmented PTFE. Transparent PTFE can be combined with pigmented PTFE by means of so-called coextrusion: Transparent virgin PTFE with a smooth surface on the inside - white pigmented PTFE on the outside: this combination provides a white appearance (since the white pigmented outer PTFE shines through the transparent inner layer) and a very smooth, transparent inner layer. Markert uses coextruded PTFE liners in all SIL300 PTFE tubing. These liners have a smoother (non-porous) surface with a lower absorption rate than pigmented white liners.6 4. PTFE in comparison PTFE can be considered the "all-purpose" material due to its excellent material properties, with a few exceptions. In the following, the properties of PTFE are compared with other highly resistant materials. MaterialMain material properties PTFE PTFE vs. siliconeDurable resistance to steam cleaning Better cleanability Broader temperature/pressure spectrum Broader chemical resistance Higher purity PTFE vs. PFAHigher flexural fatigue strength Lower coefficient of friction Better temperature application range Better price/performance ratio PFA has better low-temperature properties PTFE vs. FEPHigher flexural fatigue strength Higher flexibility Broader chemical resistance Better temperature application range PTFE has a lower coefficient of friction than FEP (0.02 vs. 0.05) FEP has better low-temperature properties PTFE vs. UPEBroader temperature range Broader chemical resistance Better UV/ozone resistance Higher purity Less weight PTFE vs. stainless steel Higher flexural fatigue strength Broader chemical resistance Higher flexibility Better cleanability7 Flexural fatigue strength is an important factor for the mechanical service life of a hose assembly. Here, PTFE offers significant advantages over PFA and FEP. According to bending tests in accordance with ASTM D2176, PTFE can withstand significantly more load cycles than PFA or FEP: 0 200.000 400.000 600.000 800.000 1.000.000 1.200.000 PTFEPFAFEP Load cycles according to ASTM Load cycles8 5. Requirement for PTFE A large number of approvals, requirements and confirmed properties appear in connection with PTFE as a material. We shed light on this and explain what is really relevant for the application. 5.1 FDA approval The FDA is the U.S. Food and Drug Administration, the government agency responsible for monitoring all goods marketed in the United States. This also includes all imports, which is why the guidelines and regulations of the US authority are also important for European manufacturers. FDA-compliant requirements need materials that have a long shelf life while not releasing ingredients into the food. The FDA is divided into various substructures. FDA21 stands for Food and Drugs, CFR for Code of Federal Regulations and Part 177 for Indirect Food additives: Polymers. This specific area of the FDA describes the approved polymers. FDA-approved PTFE is required whenever the hose assembly is used in applications and/or equipment subject to FDA approval. Markert Marsoflex PTFE tubing systems use only PTFE liners with FDA 21 CFR 177.1550 approval. The hose cover and any intermediate layers are generally not designed in accordance with FDA, since they are not in contact with the medium in the intended use. 5.2 USP Class VI Plastics used in medical technology and pharmaceuticals are divided into six biocompatibility classes in the United States Pharmacopeia (USP). To assign elastomers and other polymer materials to one of the classes, they are subjected to various tests to determine their biological reactivity in living organisms. Based on binding guidelines for the manufacture of medicinal products and medical devices, the quality of the substances tested is to be guaranteed. The correct identity of the drug substance, active ingredient strength, quality, purity and composition are evaluated. In order to obtain a USP Class VI classification, the following tests are carried out on the material itself and on various extracts of this material in external testing laboratories. Roughly, three test fields can be distinguished:9 – Acute systemic toxicity: The determination of acute irritant effect by skin contact, inhalation and ingestion is carried out. – intracutaneous reactivity: The test material is placed in direct contact with the tissue for which it is intended in normal use. – Implantation test: The reaction after implantation into the tissue of a living organism is studied. The duration is usually five days. These tests are performed at set exposure times and temperatures to ensure comparability of results. Although biocompatibility testing must take place on the finished medical device, it is important for the manufacturer that all starting materials used are also tested and meet the requirements of the final product. USP Class XI is further subgrouped in detail according to EP 3.1.9. This subcategory specifies specific tests on silicone elastomers, such as the residual peroxide content. Strictly speaking, USP Class VI approval is only required if the tubing is in continuous contact with human tissue. Markert Marsoflex PTFE hose systems use only PTFE liners with USP Class VI approval. 5.3 Freedom from GMO/BSE/TSE In the pharmaceutical industry, it may be necessary to confirm freedom from GMO/BSE/ TSE. This is a declaration that the products are free from animal ingredients and materials of animal or cell culture origin: – BSE (Bovine Spongiform Encephalopathy -' spongy change of the brain substance occurring in cattle) – TSE (Transmissible Spongiform Encephalopathy -' transmissible spongiform brain disease). – GMO (Genetically Modified Organism) The ADI-free certificate confirms that raw materials used in the manufacture of the elastomer do not contain any animal derived ingredients (ADI). Markert Marsoflex PTFE hose systems use only PTFE liners that are free of BSE, TSE, GMU and ADI.Next >