The function of the pump casing is to collect the liquid thrown by the inner impeller and convert part of the kinetic energy of the high-speed liquid into static pressure energy. The reason is that the shell shape of Dalian casting is volute, the cross-section of the runner gradually increases, the speed decreases and the pressure increases.

A pump is a machine that delivers or pressurizes fluid. It transmits the mechanical energy or other external energy of the prime mover to the liquid to increase the liquid energy. The pump is mainly used to transport water, oil, acid-base liquid, emulsion, suspended lotion, liquid metal and other liquids, as well as liquid, gas mixture and liquid containing suspended solids. Pumps can generally be divided into positive displacement pumps, power pumps and other types of pumps according to the working principle.

In addition to classification according to the working principle, it can also be classified and named according to other methods. For example, it can be divided into electric pump and hydraulic pump according to the driving method; According to the structure, it can be divided into single-stage pump and multi-stage pump; It can be divided into boiler feed pump and metering pump according to the purpose; According to the nature of the transported liquid, it can be divided into water pump, oil pump and mud pump. According to the shaft structure, it can be divided into linear pump and traditional pump. The water pump can only transport the logistics with fluid as the medium, and cannot transport solids.