The blades of centrifugal pump impeller are generally backward curved blades. There are two types of blades: cylindrical and twisted. The application of twisted blades can reduce the load of blades, improve the suction performance of centrifugal pumps and improve the cavitation resistance, but it is difficult to manufacture and the cost is high. The impeller of centrifugal pump for oil refining and chemical industry is required to be cast or welded as an integral pump impeller. The welded pump impeller is developed in recent years and is mainly used for special centrifugal pumps for chemical industry made of metal materials with poor casting performance, such as iron and its alloys. The geometric accuracy and surface finish of the welded pump impeller are better than that of the cast impeller, which is conducive to improving the efficiency of the centrifugal pump.

The closed impeller is composed of blades and front and rear cover plates. The closed impeller has high efficiency and is difficult to manufacture. It is widely used in centrifugal pumps. It is suitable for conveying clean water, solution and other clean liquids with low viscosity and without particles.