Pumps

A pump is a mechanical device that moves fluids by adding energy to the fluid. Pumps are used to raise pressure, transfer liquids between locations, or circulate fluids within systems. They differ from compressors in that they primarily increase liquid pressure rather than compress gases. Pumps can be categorized by how they move a fixed amount of fluid per cycle (positive displacement) or by how they impart energy to the fluid to create flow (dynamic).

Dynamic pumps, also called centrifugal pumps, use an impeller to accelerate fluid and convert kinetic energy into pressure. Fluid enters the center of the impeller and exits at high velocity into a volute or diffuser where energy is converted to static pressure. These pumps are common for circulating large volumes at moderate pressures. Positive displacement pumps trap a fixed amount of fluid and discharge it, producing a relatively constant flow at a given speed. Subtypes include reciprocating pumps (piston, plunger, diaphragm) and rotary pumps (gear, vane, lobe, screw).

Key components across pump types include the housing or volute, the impeller or trapping element, a drive shaft, seals, and bearings. Materials are chosen to suit the fluid, with options such as cast iron, stainless steel, aluminum, and various plastics. Performance is described by flow rate and head, while efficiency, net positive suction head (NPSH) requirements, and fluid viscosity influence selection and operation.

Common applications span water supply, irrigation, wastewater, chemical processing, oil and gas, HVAC, and food and beverage. Proper maintenance includes monitoring seals and bearings, preventing cavitation, and ensuring correct alignment and lubrication.