Fluorine Lined Magnetic Drive Pump for Pickling and Phosphating Lines A pickling line runs on hot acid and never stops, so the circulation pump becomes the weakest link in the line. This MPH-25 is built around a cast iron casing with a fully bonded FEP / PTFE fluorine lining: the acid only ever touches fluoroplastic, while the pressure boundary keeps the mechanical strength of metal. The magnetic coupling drives the impeller through a sealed wall, so there is no shaft seal to