What is the classification basis of corrosion - resistant pumps, and what are the characteristics of different categories?

Classified by: 1) Material (PVDF, PP, stainless steel, Hastelloy), 2) Structure (centrifugal, self-priming, magnetic drive, vertical), 3) Seal type (mechanical seal, magnetic drive, gland packing), 4) Application (chemical transfer, filtration, dosing, wastewater).