High Performance Centrifugal Pumps
Hydro Innovations are in a unique position to be able to offer centrifugal pumps from two very high quality manufacturers. Gorman-Rupp of the USA and EDUR Pumps from Germany, both offering performance, reliability, long service lives.
Gorman-Rupp have two series of pumps. Their “6500 Series” and their “VGH Series”. The VGH pumps for heavy duty service, pumping water and fuel based products [including ethanol], and the 6500 pumps for water or wastewater, with spherical solids handling capacities to 101mm.
EDUR have a wide range of specialist centrifugal pumps including their “Torque-Flow” series of vortex impeller pumps for handling solids up to 80mm, Industry-Block series for heavy duty pumping of water, effluent or corrosive fluids, and their excellent line of Multistage pumps for handling heavy duty high pressure applications for water or corrosive fluids.
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.
HOW DOES A CENTRIFUGAL PUMP WORK?
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
SUMMARY
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.
