The performance and longevity of a magnetic drive pump are heavily dependent on the correct selection of materials for its wetted parts, as these components must withstand corrosive attack, temperature extremes, and mechanical stress.
For the wetted-end components (casing, impeller), material choice is dictated by the chemical nature of the fluid. For highly corrosive fluids like strong acids and alkalis, fluoroplastics such as ETFE, PFA, or PVDF are the materials of choice. These offer exceptional chemical resistance and ensure the fluid medium remains free from metallic contamination. For less aggressive chemicals or higher-pressure applications, metallic constructions like stainless steel (AISI 316) are standard due to their strength and durability. In extreme cases involving high temperatures or particularly corrosive environments, high-performance alloys like Hastelloy or titanium may be utilized.
The bearings and shafts are critical for pump longevity. Since these pumps use the process fluid for lubrication, the bearing materials must have excellent self-lubricating properties and wear resistance. Silicon carbide (SiC) is widely regarded as the ideal material for sliding bearings due to its extreme hardness, high thermal conductivity, and superior corrosion resistance, making it suitable for most demanding applications
. Alternatives include high-purity alumina ceramics or carbon graphite (often impregnated with metal or resin), which are used in less severe applications.
Finally, the magnetic assembly and containment shell require careful consideration. The containment shell must be made of a non-magnetic material with high electrical resistance to minimize eddy current losses, which generate heat and reduce efficiency. Common materials include Hastelloy, titanium, or high-strength plastics. For the magnets, temperature is the deciding factor. While Neodymium (NdFeB) offers the strongest magnetic field, it is limited to applications below 120°C. For high-temperature services up to 300°C or more, Samarium Cobalt (SmCo) magnets are essential to prevent irreversible demagnetization .
