Fluoroplastics - Cleaning and Worth Knowing
All fluoroplastics, PTFE, PFA and FEP have a smooth, non-wetting surface and can usually be cleaned without any problems. Abrasive scouring agents might damage the surface and result in a milkiness of the vessels – especially those made of PFA and FEP. You may use all neutral detergents (pH 7). For a stronger contamination we recommend to use an alkaline detergent up to pH 12. Clean or dry vessels in a laboratory washing machine only when they are completely opened.
Cleaning and re-utilisation of tubing
In principle, fluoroplastic tubing shall only be reused provided the material which shall be conveyed is known and rated with + in the chemical resistance chart. If the first conveyed products or components of chemical compounds are unknown, the reuse of tubing cannot be recommended. Appropriate detergents are all water-soluble substances (such as salts, acids, lyes, etc.). Volatile solvents such as alcohols, ester, ketones, low-boiling hydrocarbons, chlorinated hydrocarbon, etc. will be reversibly dispended during aerated storage provided the substance was not absorbed by the inner layer of the tubing. After use with toxic or hazardous materials as well as with substances which only can be removed by using organic solvents, the tubing should be professionally disposed. Prior to reuse, cleaned tubing has to go through a visual inspection, respectively in case of doubt an inspection as per EN 12115 has to be made.
Autoclaving at +121 °C and 134 °C
Vessels made of PTFE, PFA or FEP can be sterilised using steam at +121 °C / 30 minutes respectively at 134 °C / 10 minutes. Besides a steam pressure sterilisation, a dry sterilisation at +160 °C is also possible. In order to avoid any plastic deformation, vessels with screw covers or stoppers have to be open while being autoclaved respectively sterilised. Autoclaving/Sterilisation of closed vessels can destroy them. Sterilisation of vessels made of fluoropolymers with high-energy radiation, gamma radiation or electron radiation is not recommended since this can cause a degeneration of the mechanical properties of the fluoropolymers.
Cleaning for trace analysis
To prevent contamination with cations or anions in trace analysis, the vessels should first be filled with an 1N HCL and HN03 solution. This solution should be left inside the vessels for maximum 6 hours at room temperature before rinsing the vessels with clean distilled water. Following test methods, which are common in the semiconductor industry, the vessel surfaces can also be cleansed by storing them for 24 hours in deionised water at +85 °C. In this case the vessels should be rinsed with deionised water as well.
Pressure resistance of bottles
Due to their thin walls, standard PTFE, PFA or FEP bottles should not be pressurised (from inside). Pressurisation could result in permanent deformation.