ABSTRACT
Pumps are divided into two fundamental types based on the manner in which they transmit energy to the pumped media: kinetic or positive displacement. In kinetic displacement, a centrifugal force of the rotating element, called an impeller, “impels” kinetic energy to the fluid, moving the fluid from pump suction to the discharge. On the other hand, positive displacement uses the reciprocating action of one or several pistons, or a squeezing action of meshing gears, lobes, or other moving bodies, to displace the media from one area into another (i.e., moving the material from suction to discharge). Sometimes the terms ‘inlet’ (for suction) and ‘exit’ or ‘outlet’ (for discharge) are used. The pumped medium is usually liquid; however, many designs can handle solids in the forms of suspension, entrained or dissolved gas, paper pulp, mud, slurries, tars, and other exotic substances, that, at least by appearance, do not resemble liquids. Nevertheless, an overall liquid behavior must be exhibited by the medium in order to be pumped. In other words, the medium must have negligible resistance to tensile stresses.
