What is meant by centrifugal pump?
A centrifugal pump is a mechanical device that uses centrifugal force acting on fluid to pump fluid using mechanical power (rotational energy).
The motor provides mechanical power in most cases. To pump fluids, a centrifugal pump employs centrifugal force. As a result, it is known as a centrifugal pump. Centrifugal power affects an object or material moving in a circular path by causing it to move away from the path’s central axis or centre point. This capability can be used to control pressure and movement within a pump unit.
It is the most common form of hydraulic equipment used to transport fluids from low to high pressure areas in a wide range of industries and in many daily gadgets. It moves fluid from one place to another using an internal impeller.
How do centrifugal pumps work?
Centrifugal pumps use one or more impellers, which are coupled and rotate with the pump axis. This provides the power to move the liquid through the pump and pressurizes the liquid to move it through the piping system. Therefore, the pump turns the mechanical energy of a motor to the energy of a moving fluid. A part of the energy becomes kinetic energy of the movement of the fluid, and another part to potential energy, represented by the pressure of the fluid or by its elevation, against gravity, to a greater height.
The transfer of energy from the mechanical rotation of the impeller to the movement and pressure of the fluid is often described in terms of centrifugal force. The exit pressure is a reflection of the pressure applied by centripetal power.
Different types of centrifugal pumps
There are four main centrifugal pumps classifications (the main distinction of each is the mechanism that operates the alternative diaphragm):
- Mechanically actuated
- Hydraulically actuated
- Solenoid and air actuated
- Double membrane pumps (AODD).
Materials of centrifugal pumps
There is a wide variety of construction materials, that go from various plastics and stamped cast iron or stainless steel for lighter duties, to bronzes, stainless steels, exotic alloys and specialty plastics for more corrosive, abrasive, hygienic or other difficult applications.
Uses and applications of centrifugal pumps
Typical applications for centrifugal pumps include:
- Liquids of all viscosities
- Chemical processes
- Pressure lubrication
- Pressure painting
- Cooling systems
- Oil burner service
- Grease management
- Liquefied gasses (propane, butane, ammonium, freon, etc..)
What are the main characteristics of a centrifugal pumps
There are two large families of pumps: centrifugal and positive displacement. Compared to the latter, centrifugal pumps are often specified for higher flow rates and to pump lower viscosity liquids. In some Chemical Plants, 90% of the pumps used are centrifugal. However, there are a number of applications for which positive displacement pumps are preferred.
What are the limitations of a centrifugal pump?
The centrifugal pump’s efficient working is based on the constant and high speed rotation of its impeller. Centrifugal pumps become increasingly inefficient with high viscosity feeds: there is a higher resistance and higher pressure is required to maintain a specific flow rate.
Sludge, such as sludge, or high viscosity oils can cause excessive erosion and overheating resulting damages and premature failures. Positive displacement pumps typically work at significant lower speeds and are less susceptible to these problems.
Another limitation is that, unlike a positive displacement pump, a centrifugal pump cannot suck dry: it must initially be primed with the pumped fluid. Therefore, centrifugal pumps are not suitable for any application where the supply is intermittent. Also, if the supply pressure is variable, a centrifugal pump produces a variable flow rate; a positive displacement pump is insensitive to pressure changes and will provide a constant output. Therefore, in applications where precise metering is required, a positive displacement pump is preferred.
Pumps at Asimer Group
Asimer Group has been collaborating with the most important European pump manufacturers for more than 10 years (FLOWSERVE, ANDRITZ, SULZER).
The knowledge of the centrifugal pump and the experience accumulated in its development has allowed the ASIMER Group to «penetrate» the world of the industrial pump, with increasingly complex materials, and critical quality requirements, mainly framed in the dimensional tolerances, surface finishes and NDTs (Non Destructive Test)