A pump is a machine that delivers fluid or pressurizes fluid. It transfers the mechanical energy of the prime mover or other external energy to the liquid to increase the liquid energy. The pump is mainly used to transport liquids such as water, oil, acid-base liquid, emulsion, suspension emulsion and liquid metal, and can also transport liquid, gas mixture and liquid containing suspended solids. Pumps can usually be divided into three categories according to their working principles: positive displacement pumps, power pumps and other types of pumps. In addition to classification according to working principles, it can also be classified and named according to other methods. For example, according to the driving method, it can be divided into electric pumps and water turbine pumps; according to the structure, it can be divided into single-stage pumps and multi-stage pumps; according to purposes, it can be divided into boiler feed water pumps and metering pumps; according to the nature of the conveying liquid, it can be divided into Water pump, oil pump and mud pump etc. According to the shaft structure, it can be divided into linear pump and traditional pump. Water pumps can only transport fluids as a medium, not solids.

In the production of the chemical and petroleum sectors, most of the raw materials, semi-finished products and finished products are liquids, and the raw materials into semi-finished products and finished products need to go through a complicated process. In these processes, pumps play a role in transporting liquids and providing pressure flow for chemical reactions. In addition, pumps are used to regulate temperature in many devices.

In agricultural production, pumps are the main irrigation and drainage machinery. In the mining and metallurgical industries, pumps are also the most used equipment. The mine needs to use pumps to drain water, and in the process of beneficiation, smelting and rolling, pumps are needed to supply water.

In the power sector, nuclear power plants require nuclear main pumps, secondary pumps, and tertiary pumps, and thermal power plants require a large number of boiler feed water pumps, condensate pumps, oil-gas mixed pumps, circulating water pumps, and ash pumps.

In the construction of national defense, pumps are required for adjustment of aircraft flaps, rudder and landing gear, rotation of warships and tank turrets, and ups and downs of submarines. High-pressure and radioactive liquids, and some require no leakage from the pump.

In short, whether it is airplanes, rockets, tanks, submarines, drilling, mining, trains, ships, or daily life, pumps are needed everywhere, and pumps are running everywhere. Because of this, the pump is classified as a general-purpose machine, which is a major product in the machinery industry.

Electric pumps are pumps driven by electricity. The electric pump is composed of a pump body, a pumping pipe, a pump seat, a submersible motor (including cables) and a starting protection device. The pump body is the working part of the submersible pump, which is composed of water inlet pipe, diversion shell, check valve, pump shaft and impeller. There are two ways to fix the impeller on the shaft.