The impeller of a centrifugal pump generally consists of four parts: blades, front cover, rear cover and hub. According to the type of dry type, it can be divided into closed impeller. There are three structures: semi-open impeller and open impeller.
1. A closed impeller means that the flow passage is relatively closed, and a closed flow passage is formed between the front cover plate, the rear cover plate and the blades. It is suitable for conveying high-density, clean liquids. Closed impellers have two structures: single-suction impellers and double-suction impellers.
2. Semi-open impeller means that the impeller flow channel is semi-closed. Compared with a closed impeller, it has no front cover and is suitable for transporting liquids containing solid particles or impurities.
3. An impeller without front and rear covers is called an open impeller. Suitable for transporting slurry or fiber media.
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The impeller of a centrifugal pump transfers the energy of the prime mover to the liquid in the pump through centrifugal force, causing the liquid to increase speed and pressure, causing the liquid in the pump to be discharged, and the liquid in the inlet pipeline to be sucked in.
Commonly used materials for impellers include: cast iron HT20~40, HT25~47, cast steel ZG15, ZG25, cast copper ZGCuR, stainless steel 1Cr13, 2Cr13, 1Cr18Ni9Ti, and aluminum cast iron.
Impellers can be divided into four forms according to their different structures: the first form is composed of a front cover, a rear cover, blades and a hub, and is called a closed impeller (Figure a); One form, consisting of a back cover, blades and hub, is called a semi-open impeller (Figure b); the third form, consisting of blades and hub, is called a fully open impeller (Figure c); the fourth form , 7 consists of two front covers, blades and hub, with two suction inlets distributed on both sides, which is called a double-suction impeller (Figure d).
Semi-open and fully-open impellers are often used to transport liquids containing more impurities; double-suction impellers are often used in situations with large displacements, with good cavitation resistance and relatively high efficiency.