A centrifugal pump uses centrifugal force to pump a liquid containing solids. Centrifugal force is generated by the rotation of the impeller, which causes the liquid to leave the impeller's vanes at a higher velocity than it had when it entered. In turn, this outward flow creates a pressure differential. Pressure is lowest at the impeller eye, which allows more liquid to enter - resulting in a constant flow of liquid through the pump.
What differentiates a self-priming centrifugal pump from a standard centrifugal pump is the ability to pump liquid without the pump casing being entirely filled with liquid - thanks to the inclusion of a partial vacuum that allows self-priming pumps to rid themselves of air. Both standard and self-priming centrifugal pumps are an integral part of the water desalination, mining and petrochemical industries amongst others.
Water desalination plants are more vital than ever. By separating dissolved salts and other minerals from otherwise unusable water, water desalination plants are able to recover potable water for the areas that need it most. And, although desalination methods vary dramatically (from nanofiltration to electrodialysis), what unites these processes is the inclusion of centrifugal pumps. More than capable of transporting solid-containing seawater efficiently, self-priming centrifugal pumps are especially popular with high capacity water desalination plants.
The mining industry is unconventional in that it uses centrifugal pumps in an altogether different manner to similar industries. In the context of mining, despite being the same mechanism structurally, a centrifugal pump is known as a froth pump, because of the product it is altered to produce. Mineral processing owes the separation of precious minerals from gangue and bitumen to the intervention of centrifugal pumps. As well as actually playing a part in processing the minerals themselves, centrifugal pumps are also used to transport the slurries and solid-containing fluids that accumulate during the mining process.
The petrochemical industry is an industry with a heavy reliance on centrifugal pumps. Given not only the value of the petrochemical components at play, but also the very real danger of them igniting means that the robustness of the centrifugal pumps involved is of utmost importance. Consequently, the production of plastics, rubbers and dyes is indebted to the use of well-designed centrifugal pumps.