Pump is a special piece of machinery that applies mechanical actions to cause the replacement of fluids or gases. These pieces of machinery are often utilized in industries like mining and construction that require constant supply of gases or fluids transported from distant places, or transporting huge amounts of substances. These pieces of machinery are also applied in medicine for creating sophisticated prosthetics and artificial organs.

Such devices can be separated into two main categories - positive displacement and centrifugal. The first type works by separating a determined amount of substance and applying force to it, thus moving it to a desired outlet. The second type transforms the rotational energy of an internal mechanism into a movement energy. The substance is affected by the rotor, and starts moving outwards through the determined outlet. Centrifugal type pumps are often utilized in HVAC/R systems. Their variability in construction allows them to be used in many types of HVAC/R structures.