The pump is one of the most significant inventions in the history of humankind. Pumps allow liquids (and sometimes solid particles) to be efficiently moved from one place to another and pressurized for use. Archimedes of Syracuse is credited with coming up with one of the first practical pump designs in the 3rd Century BC. His Archimedes’ screw was an early positive displacement pump that was used for irrigation purposes.
As you might reasonably expect, pump technology has improved and diversified since the time of the ancient Greeks. This article is a quick look at some of the most important kinds of pumps used in modern industry.
Axial flow pumps are relatively simple but immensely powerful and useful. They essentially consist of a series of propellers in a pipe – forcing gasses and liquids at high pressure along a straight path. Axial flow pumps are most notably used in turbojet engines, where they create channels of high-pressure air that is very combustible when injected with jet fuel. In industry and agriculture, axial flow pumps are used to move irrigation waters and sewage. Small-scale axial flow pumps are particularly popular in Asia – where farmers regularly use them in the movement of liquid from irrigation ditches.
Peristaltic pumps are used to move materials that might cause traditional pumps to clog up, and peristaltic pumps are designed so that the material never has to come into contact with the pump’s moving parts – remaining within a heavy-duty hose. The hose is compressed by two rotating ‘shoes’. Because the shoes are equally dispersed, liquids are allowed into a central section and then are forced out successively. Although these pumps are less efficient at moving large loads than some other models, they are absolutely essential for moving caustic liquids and abrasive materials that would severely damage any other kind of pump.
Jet pumps make use of the sucking motion generated when a liquid is forced into and out of a small nozzle. They work a little bit like a straw. An impeller sucks liquid into a chamber and then forces it through a small hole. The changes in pressure caused by this cause the pump to suck up more liquid, and the process repeats without the need for an impeller.
Electromagnetic pumps are used to move magnetically charged materials such as liquid metals. Instead of provoking liquid movement through kinetic force, these pumps use electromagnetism. They are used in metalworking industrial plants and also for the cooling of nuclear power plants. Powerful magnets within the pump are positioned in such a way that the positive and negative charges provoke movement in the materials. Materials that are very difficult to handle can be controlled using this system in a very safe and predictable way, thanks to the constant electromagnetic forces imposed upon them. Because they lack moving parts, these pumps are perfect for high-temperature environments where traditional pumps would expand or contract too much for use.