When selecting plastic diaphragm pumps (including AODD and EODD drives), engineering specifications require choosing between Polypropylene (PP) and Polyvinylidene Fluoride (PVDF) fluid paths. ### Polypropylene (PP) Characteristics PP is a highly cost-effective polymer with excellent chemical resistance to mild acids, alkalines, and standard inorganic compounds. However, it is limited to a maximum temperature of 70°C and is vulnerable to highly concentrated oxidizing acids (e.g. concentrated Nitric or Hydrofluoric acid). ### PVDF (Kynar) Characteristics PVDF exhibits superior chemical compatibility and handles highly aggressive concentrated acids, halogens, and chlorinated solvents. It boasts a higher temperature limit (up to 90°C) and higher structural tensile strength, preventing housing flexing under extreme pressure loops. ### Selection Matrix Choose PVDF for organic solvents, chemical processing loops exceeding 60°C, or concentrated nitric/hydrochloric acids. Choose PP for plating bath circulations, general wastewater sludge transfers, and battery charging chemicals.

Polypropylene vs. PVDF Casing Materials Guide