A pump is a mechanical device that transports or pressurizes liquids. It transfers the mechanical energy or other external energy of the prime mover to the liquid, increasing the energy of the liquid. 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 usually be classified into three types based on their working principles: positive displacement pumps, power pumps, and other types of pumps. In addition to classification based on 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 hydraulic pumps, etc; According to structure, it can be divided into single-stage pumps and multi-stage pumps; According to their purposes, they can be divided into boiler feed pumps and metering pumps, etc; According to the properties of the transported liquid, it can be divided into water pumps, oil pumps, and mud pumps. There is a certain interdependence between the various performance parameters of a pump, which can be represented by a curve called the pump characteristic curve. Each pump has its own specific characteristic curve.
The definition and historical origins of pumps
A machine that transports or pressurizes liquids. In a broad sense, a pump is a mechanical device that transports fluids or pressurizes them, including some mechanical devices that transport gases. The pump transfers the mechanical or other energy from the prime mover to the liquid, increasing the energy of the liquid.
The improvement of water is crucial for human life and production. There were various water lifting devices in ancient times, such as the Egyptian chain pump (17th century BC), the Chinese orange gourd (17th century BC), the pulley (11th century BC), the water wheel (1st century AD), and the spiral rod invented by Archimedes in ancient Greece in the 3rd century BC. Around 200 BC, the ancient Greek craftsman Ctesibius invented the most primitive piston pump - the fire pump. As early as 1588, there were records of 4-blade slide pumps, and various other rotary pumps have emerged since then. In 1689, D. Papin of France invented the volute centrifugal pump with four blade impellers. In 1818, centrifugal pumps with radial straight blades, semi open double suction impellers, and volutes appeared in the United States. From 1840 to 1850, H.R. Worthington of the United States invented a piston pump with a pump cylinder and a steam cylinder facing each other, which directly acted on steam, marking the formation of modern piston pumps. From 1851 to 1875, multi-stage centrifugal pumps with guide vanes were successively invented, making it possible to develop high head centrifugal pumps. Subsequently, various pumps were introduced one after another. With the application of various advanced technologies, the efficiency of pumps is gradually improving, and the performance range and applications are also expanding.
Classification criteria for pumps
There are many types of pumps, which can be divided into:
① Power pumps, also known as impeller pumps or vane pumps, rely on the rotating impeller to continuously transfer energy to the liquid, increasing the kinetic energy (mainly) and pressure energy of the liquid. Then, the kinetic energy is converted into pressure energy through the extrusion chamber. They can be divided into centrifugal pumps, axial flow pumps, partial flow pumps, and vortex pumps.
② Positive displacement pumps rely on the periodic changes in the volume of the sealed working space that contains the liquid to periodically transfer energy to the liquid, increasing the pressure of the liquid to forcibly discharge it. According to the motion form of the working components, they can be divided into reciprocating pumps and rotary pumps.
③ Other types of pumps transmit energy in other forms. If a jet pump relies on high-speed injection of working fluid to suck the fluid to be transported into the pump and mix it, momentum exchange is carried out to transfer energy; The water hammer pump utilizes the flow of water during braking to raise it to a certain height and transfer energy; An electromagnetic pump is used to transport liquid metal that is energized by electromagnetic force. In addition, pumps can also be classified according to the nature, driving method, structure, and purpose of the liquid being transported.
