What is a Centrifugal Pump?

By definition, a centrifugal pump is a machine. More specifically, it is a machine that imparts energy to a fluid. This energy infusion can cause a liquid to flow, rise to a higher level, or both.

A centrifugal pump is a very simple machine. It is one of many kinds of rotary machines, which are devices that include an impeller (rotary element) and a casing to hold the impeller. The figure below shows a cross-section of a centrifugal pump.

A centrifugal pump impeller increases the fluid’s speed and pressure as it moves it toward the discharge pipe of the pump. The pump casing constricts the direction of the fluid from the inlet pipe, directs it into the pump, and slows and controls the flow before release.


The impeller is a key component in a centrifugal pump. It consists of curved vanes which can number anywhere from one (screw impeller) through to six. For fluids with entrained solids, an open or semi-open impeller backed by a single disc is better.

The fluid enters the centre of the impeller at its eye, exits between the vanes surrounding the eye, and is accelerated by centrifugal force out into the pump casing. The motor turns the impeller, which rotates at a high speed (typically 500-3000 rpm) to move the water through the system.

In a volute casing, the impeller is offset, effectively creating a curved funnel with an increasing cross-sectional area towards the pump outlet. This design causes the fluid pressure to increase towards the outlet.

Centrifugal Pump Performance is usually expressed in terms of the following of its characteristics:

Capacity (Q) – expressed in volumetric units in a given time i.e.; litres per second
Head (H) – measured in kilopascals (kPa) or metres (m)
Power (P) – kW
Speed (N) – revolutions per minute (RPM) or revolutions per second (RPS)
Efficiency (תּ) – as a ratio of useful work performed against power input



Centrifugal pumps are simple and efficient low-cost solutions to most low-pressure, high-capacity pumping applications involving low-viscosity fluids, such as water, solvents, chemicals and light oils. Typical applications include water supply and circulation, irrigation and the transfer of chemicals in petrochemical plants. Positive displacement pumps are preferred for applications involving highly viscous fluids such as thick oils and slurries, especially at high pressures, for complex feeds such as emulsions or biological fluids. They are also useful for accurate dosing when required.

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Centrifugal Pump Videos

Watch short animated videos here showing the simple, effective concept of Centrifugal pumps:

How does a Centrifugal pump work?



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6500 Series® end suction centrifugal pumps are based on the proven technology of Gorman-Rupp’s Prime Aire® and Prime Aire Plus® priming-assisted pump models. The 6500 Series was designed to extend Gorman-Rupp’s end suction centrifugal pump offering and to better serve applications where a suction lift is not required.  A double volute mitigates shaft breakage and extends the life of the mechanical seals, wear rings and bearings, all while maintaining hydraulic efficiency, while a side access port allows for easy access to pump interior for inspection and clean out while the pusher bolt capability assists in the removal of the suction flange.

Advantages include:

  • High efficiency
  • Alloy steel shafts with stainless steel options
  • Dual sight gauges for bearing and seal cavities
  • Smart Scroll® indexable discharge location
  • Atmospheric vent
  • Oversized bearings for longer bearing life
  • Double volute on larger models
  • Solids-handing models include side access for inspection and clean out

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The Gorman-Rupp O Series pumps were originally designed for handling petroleum products. Later, O Series pumps were introduced into the industrial market for effective handling of solvents and similar liquids, as well as excellent clean liquids handling. The straight-in-suction design without a check valve eliminated entrance restrictions provides quick, reliable self-priming with few moving parts offering saving through minimal maintenance and increased efficiency. The O Series has a variety of seal configurations to choose from allowing it to handle a number of different liquids.

Advantages include:

  • Capital cost savings over wet well/ dry well constructions
  • Low cost of ownership
  • Easy access for monitoring or service
  • Purpose design of PTO from tanker trucks

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The Gorman-Rupp VG and VGH Series range of standard centrifugal pumps come in two styles. A general purpose style (VG) for clean liquids and a heavy duty style (VGH) for clean petroleum fluids as well as dirty water and mild abrasives.

The VG centrifugal pump has a cast iron casing and impeller, whereas the VGH centrifugal pump has a ductile iron casing, cast iron impeller with replaceable iron wear rings and a tungsten carbide/silicon carbide cartridge type mechanical seal with fluorocarbon elastomers.

Advantages include:

  • High efficiency
  • Ethanol capable [with a seal upgrade]
  • Low lifecycle costs
  • Hand primer kit available in some centrifugal pump models

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The EDUR range of multi-stage centrifugal pumps can deliver flows to 45 litres per second and heads to 300 metres. They are also available in a variety of materials (Cast Iron, All Bronze, All Stainless Steel and Super-Duplex) enabling them to pump corrosive fluids including seawater. These centrifugal pumps are ideal for booster systems, boiler feed and condensate systems, washing plants, water treatment and hardening systems.

Pumps can be close or long-coupled. Advantages include:

  • All Iron, All Bronze, All Stainless Steel and Super-Duplex construction
  • Flows to 16 l/s
  • Head: max. 300 m
  • Discharge pressure: max. 21,4 bar
  • Operating pressure: max. 40 bar
  • Handle temperatures -50 °C to 160 °C
  • Viscosity: The NH series are able to handle media with a viscosity up to 200 cSt, while the other series of multistage centrifugal pumps can handle viscosities up to 115 cSt
  • Single and double mechanical seals available along with gland packing and water cooled gland packing

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The EDUR range of Industry Bloc close-coupled centrifugal pumps are ideal for pumping water and other clean and slightly polluted fluids. They are compact in size, and available in a variety of materials of construction including cast iron, bronze and stainless steel.

Motors are either 2 pole or 4 pole, with IP55 enclosures, and insulation class F.

Advantages include:

  • Flows to 166 l/s
  • Heads to 98m
  • Handle temperatures from -50 °C to 140 °C
  • Handle viscosity to 200 cSt
  • Handle solids content

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Hydro Innovations is proud to distribute a broad range of quality, reliable and industry-leading industrial pumps and aerators.

We are also delighted to share that Hydro Innovations is proud to be the exclusive distributor of Gorman-Rupp Pumps.

Gorman-Rupp is the world leader in self-priming centrifugal wastewater pump technology, and invests heavily in R&D, and in training for their international representatives – like Hydro Innovations.

This puts us in an excellent position to make the very best recommendations for our Australian customers.

Our other suppliers, Ragazzini of Italy and EDUR of Germany, are also world leaders in their respective technologies (Peristaltic Pumps – Ragazzini, and Specialist centrifugal pumps – EDUR).

We carry a very large inventory of pumps and spare parts for all of these brands, to help us to deliver industry-leading service.

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