Centrifugal Pump Impeller Material For Various Applications
🔗What is impeller in centrifugal pump?
When choosing impeller materials, apart from cost and abundancy, many other properties of material like abrasion and corrosion resistance need to be considered.
- Cast iron: When it is necessary to pump clear and fresh water, the impeller is cast as a single piece and made of cast iron. This impeller type is cheaper than those made of other materials, such as brass or bronze. Cheapest option but still a good performer. It has good corrosion resistance to neutral and alkaline liquids, but not suitable for acidic liquids.
- Duplex and super duplex: It is high-grade stainless steel. It is the most corrosion resistant material. Resistant to localized corrosion like a crevice, intergranular and stress cracking. They are suitable for water treatment, seawater, and fire pumps. Stainless steel is used to make machines in the milk industry to prevent contamination of the liquids handled.
- Bronze: When pumping liquid that causes corrosion due to salt, material such as gunmetal and stainless steel is used for the impeller. Gunmetal is a type of bronze. It has higher corrosion erosion and cavitation resistance than cast iron material. They are very good choice for power generation, seawater, offshore gas and oil application. Advantages of bronze include high wear resistance, high compression strength, ability to dry run etc.
- Cast steel impeller with special packing is used for making impeller where it is required to pump liquid having a temperature above 150°C.
- When acids are pumped, the impeller and all surfaces in contact with the liquid should be coated with a suitable material to resist corrosion.