Centrifugal Pumps: Introduction and Types

by Sweta Shah HR Executive in Ambica Machine Tools

Centrifugal pumps are the most popular type of pumps that are used in various industries for transferring fluids. It uses rotating impeller which is attached to the shaft to move fluids using the centrifugal force. They are a very commonly used pump for delivering liquids to the desired location in industries like agriculture, power generation plants, mining, petroleum, chemical, and many others. Centrifugal pumps are widely used since they are capable of handling a large quantity of fluids and provide a high flow rate.

Types of Centrifugal Pumps

Centrifugal pumps are classified into various types depending on the factors like design, construction, service, application, compliance with national standards etc. It may happen that one pump can fall into various types depending on its construction. Let’s have a look into various types of centrifugal pumps distinguished by various factors.

Based on the number of impellers

Single stage – It has one impeller pump with simplistic design and easy maintenance. Ideal for low-pressure installations and large flow rates; commonly used for pumping high flow and low or moderate TDH.

Two-stage – With two impellers operating side-by-side, two stage pumps are used in medium head applications.

Multi-stage – Majorly used for high head applications with three impellers present in a series.

Based on the type of flow

Radial flow – In this type, liquid enters at the center part of the impeller and is directed out at a right angle to the pump shaft.

Axial flow – In axial flow pumps, the fluid is moved parallel to the pump shaft. They are also called propeller pumps.

Mixed flow – As the name suggests, it has the mixed characteristics of both radial and axial flow pumps. Here, the impeller blades move the liquid away from pump shaft and direct at an angle greater than 90-degrees to the pump suction.

Based on the type of impeller design

Single suction – In this type, impeller allows the fluid to enter through one side. Due to flow force on one side, it has an axial thrust imbalance.

Double Suction – It is equipped with the double suction pump with fluid entering to the blades from both sides.

Based on bearing support

Overhung – Here impeller is placed at the end of the shaft and is supported by bearing on just one side. It has a horizontal placement of shaft which can even be vertical with a different bearing configuration.

Between bearing – Impeller is placed on the shaft with bearings support present on both the sides. Briefly, the impeller is present in between the bearings.

Based on the type of volute

Single volute – Here there is a single narrow volute passage and is usually used as a low capacity pump.

Double volute – Here, there are two partial volutes which are 180-degrees apart to balance the radial load

Based on the orientation of the shaft

Shaft is an essential characteristic which classifies the centrifugal pumps into different types.

Horizontal – In these pumps, the shaft is present on the horizontal plane providing maintenance ease.

Vertical – In vertical centrifugal pumps, shaft is located in the vertical plane forming a unique bearing support and shaft combination that leaves the volute hanging while bearings are placed outside the sump.

Based on the industry standards

Centrifugal pumps are also distinguished based on the industry standards and its applications in that particular industry. Based on different quality and industry standards there are various types available such as ANSI Pump, API Pump, DIN Pump, ISO Pump, and Nuclear Pump.