Understanding the basics of two of the most widely used pumps

Centrifugal Pumps

Over the years, pumps have undergone immense technological advancements in terms of consistence performance and operational safety. There are a bewildering range of pumps that are commercially available today in the market for diverse industrial as well as household applications. This article briefly describes the design, operation and applications of centrifugal pumps & liquid ring pumps.

Generally, pumps are devices to transfer liquids or fluids from one place to another. Application of pumps is virtually in every field. Depending on the application, pumps can vary from advanced pumps for industrial use to simpler pumps used at homes or in fish ponds. One of the most widely used pumps out of the host of pumps available in the market is centrifugal pumps.

In 1475 according to Reti, the early device that could be classified as a centrifugal pump was a mud lifting machine. Centrifugal pumps that can be truly characterized were not built until late 17th century. It was Denis Papin who built a centrifugal pump using straight vanes. A centrifugal pump, like most pumps, convert motor’s mechanical energy to energy of a moving fluid. A part of this energy leads into kinetic energy of the fluid and remaining part into potential energy of fluid pressure or by lifting the fluid to a higher altitude, against gravity.

When the mechanical rotation of the impeller leads to the motion and pressure of the fluid, it is described as centrifugal force.

Vertical Centrifugal Pumps

One of the many types of centrifugal pumps is Vertical Centrifugal Pumps. They are also referred to as Cantilever Pumps. The configuration of cantilever pumps consists of a unique shaft and bearing support to allow the volute to hang in the sump and the bearings are fitted outside of the sump. A parts washer is the common application of these pumps that uses a throttle bushing instead of stuffing box to seal the shaft.

Liquid Ring Pumps

Liquid ring pumps are usually remarkably simple unit that function on only a single moving part. The single most moving part in liquid ring pumps – vaned impeller is made up of central hub mounted on a shaft. There are number of curved vanes on this hub at regular intervals. This entire configuration of the pump is built within a closed chamber which forms the pump body.

These pumps have typical application as a vacuum pump. However, they can also be utilized as a gas compressor. The function of a liquid ring pump can be compared to a rotary vane pump but the only difference being the essential role of vanes. Vanes in liquid ring pumps are an integral part of the rotor as they churn the liquid and form the seal for compression chamber. Liquid ring vacuum pumps tend to be an inherently pumps with a low friction design as the rotor is the only moving part. Liquid ring pumps can be powered by an induction motor and can be single or multistage.

The author writes for Premier Fluid Systems Inc. which specializes in marketing and servicing the pumps and systems of Travaini, PVR-Rotant and other quality brand names. The Company’s primary products include liquid ring pumps, liquid ring compressors, centrifugal pumps, rotary vane vacuum pumps and vacuum systems.