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).