page_title: Pump
section_title: Velocity pumps
hierarchical_section_title: Pump / Types / Velocity pumps
caption_attribution_description: English: Schematic of centrifugal pump dynamicsItaliano: Schema dinamico di una pompa centrifuga
context_page_description: A pump is a device that moves fluids, or sometimes slurries, by mechanical action, typically converted from electrical energy into Hydraulic energy. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift, displacement, and gravity pumps.
  Pumps operate by some mechanism, and consume energy to perform mechanical work moving the fluid. Pumps operate via many energy sources, including manual operation, electricity, engines, or wind power, and come in many sizes, from microscopic for use in medical applications, to large industrial pumps.
  Mechanical pumps serve in a wide range of applications such as pumping water from wells, aquarium filtering, pond filtering and aeration, in the car industry for water-cooling and fuel injection, in the energy industry for pumping oil and natural gas or for operating cooling towers and other components of heating, ventilation and air conditioning systems. In the medical industry, pumps are used for biochemical processes in developing and manufacturing medicine, and as artificial replacements for body parts, in particular the artificial heart and penile prosthesis.
context_section_description: Rotodynamic pumps (or dynamic pumps) are a type of velocity pump in which kinetic energy is added to the fluid by increasing the flow velocity. This increase in energy is converted to a gain in potential energy (pressure) when the velocity is reduced prior to or as the flow exits the pump into the discharge pipe. This conversion of kinetic energy to pressure is explained by the First law of thermodynamics, or more specifically by Bernoulli's principle.
  Dynamic pumps can be further subdivided according to the means in which the velocity gain is achieved.
  These types of pumps have a number of characteristics:
  Continuous energy
  Conversion of added energy to increase in kinetic energy (increase in velocity)
  Conversion of increased velocity (kinetic energy) to an increase in pressure head
  A practical difference between dynamic and positive-displacement pumps is how they operate under closed valve conditions. Positive-displacement pumps physically displace fluid, so closing a valve downstream of a positive-displacement pump produces a continual pressure build up that can cause mechanical failure of pipeline or pump. Dynamic pumps differ in that they can be safely operated under closed valve conditions (for short periods of time).
caption: A centrifugal pump uses an impeller with backward-swept arms
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