The basic principle on which a centrifugal pump works is that when a certain mass of liquid is made to rotate by an external force, it is thrown outwards from the axis of rotation and a centrifugal head is impressed on it. This elegantly simple mechanism\u2014accelerating fluid and then converting its velocity into pressure\u2014makes the centrifugal pump the workhorse of modern industry, found everywhere from municipal water supply and wastewater treatment plants to chemical processing, mining operations, and power generation facilities.<\/p>\n\n\n\n Understanding how a centrifugal pump works and how to select the right one is fundamental knowledge for engineers, technicians, and anyone involved in fluid handling. Drawing on over two decades of pump engineering and manufacturing experience, Changyu Pump brings deep expertise in centrifugal pump design, material selection, and application-specific configuration. This guide provides a comprehensive reference covering the working principle, main components, classification system, key performance parameters, industrial applications, and a practical selection framework.<\/p>\n\n\n\n A centrifugal pump operates through a continuous three-step process that converts mechanical energy into fluid energy. The entire cycle can be summarized as follows:<\/p>\n\n\n\n In essence: the impeller adds kinetic energy to the fluid, and the volute converts that kinetic energy into pressure energy.<\/strong> This two-stage energy conversion is the defining characteristic of every centrifugal pump, regardless of its size, configuration, or application.<\/p>\n\n\n\n A centrifugal pump generates flow, and the pressure developed is a measure of the system’s resistance to that flow. In practice, the pump must develop sufficient pressure to overcome this resistance, and it does so by converting the kinetic energy imparted to the fluid into pressure energy within the volute. The gauge pressure is a measurement of the resistance to flow.<\/p>\n\n\n\n In fluid dynamics, the term “head” is used to measure the kinetic energy that a pump creates. Head is a measurement of the height of the liquid column the pump could create from the kinetic energy the pump gives to the liquid. The key advantage of using head instead of pressure is that the pressure from a pump will change if the specific gravity of the liquid changes, but the head will not. The pump’s performance on any Newtonian fluid can always be described by using the term head. For a deeper understanding of how pump head relates to system design, see our centrifugal pump pressure calculation guide<\/a>.<\/p>\n\n\n\n The relationship between flow rate, head, power consumption, and efficiency is captured in the pump performance curve<\/strong>\u2014the most important document for selecting and evaluating a centrifugal pump.<\/p>\n\n\n\n Operating the pump near its BEP is critical: running far to the left or right of the BEP accelerates wear, increases vibration, and wastes energy. A pump selected solely on flow and head without verifying its position on the performance curve may be inefficient from the day it is commissioned.<\/p>\n\n\n\n NPSH is the abbreviation of “net positive suction head” and is an important factor in evaluating the suction characteristics of a centrifugal pump. It allows a prediction to be made regarding the safety margin required to avoid the effects of\u00a0cavitation<\/a>\u00a0during operation. <\/p>\n\n\n\n Two values must be compared:<\/p>\n\n\n\n Cavitation occurs when the NPSHA is lower than the NPSHR<\/strong>. When the local pressure inside the suction eye of the impeller drops below the vapor pressure of the fluid being pumped, vapor bubbles form and then collapse violently as they move into higher-pressure zones, producing noise, vibration, and pitting damage to the impeller surface. Common causes include a suction line that is sized too small, is too long, or contains too many bends and fittings, and too high a fluid temperature.<\/p>\n\n\n\n To prevent cavitation, start with a correct NPSH calculation during plant design, ensure adequate suction line diameter, minimize bends and fittings, and verify that the pump operates within its recommended flow range. The NPSHA must exceed the NPSHR by an adequate margin\u2014typically 0.5\u20131.0 meter or NPSHA > 1.3 \u00d7 NPSHR.<\/p>\n\n\n\n A centrifugal pump has five main parts: the casing (called a volute), the impeller, the backplate, the bearings, and the shaft that connects the impeller to the engine or motor. Each component plays a critical role in the pump’s operation.<\/p>\n\n\n\n The impeller is the rotating component that imparts kinetic energy to the fluid. It is the most critical component of the pump, as its design directly determines the pump’s efficiency, flow characteristics, and suitability for different applications.<\/p>\n\n\n\n The volute<\/a> collects the liquid discharged from the impeller at high velocity and gradually causes a reduction in fluid velocity by increasing the flow area. This converts the fluid’s kinetic energy into pressure energy.<\/p>\n\n\n\n Two main designs exist:<\/p>\n\n\n\n The shaft connects the impeller to the drive system (e.g., motor) and transfers mechanical energy to the impeller. It is fully protected from the liquid to be pumped by means of fully enclosed gaskets between the impeller nut, shaft end, and shaft sleeve. A properly dimensioned shaft exhibits minimum deflection at the stuffing box, resulting in long operational life for mechanical seals.<\/p>\n\n\n\n Bearings support the shaft and ensure its smooth rotation. They are typically made of alloy steel or stainless steel and are located in the bearing housing, which provides lubrication and maintains shaft alignment.<\/p>\n\n\n\n Seals serve the critical function of containing and preventing the leakage of fluid along the rotating shaft. This is essential in maintaining the pump’s efficiency and preventing environmental contamination.<\/p>\n\n\n\n Common seal types include:<\/p>\n\n\n\n![\"What-Is-a-Centrifugal-Pump-Working-Principle,-Types-&-Selection-Guide\"](\"https:\/\/changyupump.com\/wp-content\/uploads\/2026\/05\/What-Is-a-Centrifugal-Pump-Working-Principle-Types-Selection-Guide.webp\")
<\/figure>\n\n\n\n1. Centrifugal Pump Working Principle: How Does It Work?<\/h2>\n\n\n\n
1.1 The Working Principle<\/h3>\n\n\n\n
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1.2 Understanding Pressure and Head<\/h3>\n\n\n\n
1.3 Understanding the Pump Performance Curve<\/h3>\n\n\n\n
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1.4 Critical Concept: Net Positive Suction Head (NPSH)<\/h3>\n\n\n\n
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2. Main Parts and Impeller Types of a Centrifugal Pump<\/h2>\n\n\n\n
2.1 Impeller Types and Their Applications<\/h3>\n\n\n\n
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2.2 Casing (Volute)<\/h3>\n\n\n\n
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2.3 Shaft and Bearings<\/h3>\n\n\n\n
2.4 Seals<\/h3>\n\n\n\n
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2.5 Centrifugal Pump Parts Summary<\/h3>\n\n\n\n