This pressure increase can be anywhere from several dozen to several hundred psid across a centrifugal pump with a single stage impeller. Running too far out on the curve, or too far back, can cause damage to the pump, excessive energy consumption, and overall poor performance. The wrong pump will not only operate inefficiently, but. Knowing how to read a centrifugal pump curve is essential to the health of your system. Figure 4 shows a typical head, h ft, versus capacity discharge, q gpm, curve for a singlestage. Centrifugal pumps sample pump curve 3500 is the rpm impeller size 6.
Choosing the correct centrifugal pump for your application is critical for maximizing longterm performance. Pump characteristic an overview sciencedirect topics. Each feedpump is a multistage centrifugal pump producing 150 ls at 21 mpa. Centrifugal pump exercise b objective to create head, power and efficiency characteristic curves for a centrifugal pump. In some cases an additional pressure behind the impellers to the point that the. Operating characteristic curves of a centrifugal pump. This paper describes the technique of determining the complete operating characteristics of a hydraulic machine such as a centrifugal pump. How to select a centrifugal pump examples of total head calculations sizing a pump for a home owner application 14. Jun 23, 2016 lets first go through the characteristic curves of centrifugal and reciprocating pump so that the ones referring it for the first time also get the idea of it. A typical composite curve includes the pump performance curves, horsepower curves. Casing design radial axial radial axial stage casing.
What is total head 10 what is the relationship between head and total head 11. Sulzer pumps, in centrifugal pump handbook third edition, 2010. To change the operating point either the system curve or the pump curve must be changed. The efficiency of centrifugal pumps varies over the individual curve. Secondary objectives are to familiarize the student with the characteristics of a centrifugal pump and to introduce the student to the homologous scaling relationships. Centrifugal pump pump curves pumps can generate high volume flow rates when pumping against low pressure or low volume flow rates when pumping against high pressure. Understanding centrifugal pump curves when selecting a centrifugal pump, one should match the performance of the pump to that needed by the system. Pump headflow curves are typically given for clear water. This tech brief examines how pump curves can provide data about a pumps ability to produce flow against certain head, shows how to read a typical centrifugal pump curve, and provides.
For the choice of the right pump, the system characteristic curve or data must be known about it. Pdf dimensionless characteristics of centrifugal pump. The pump curve also displays the pump model, the pump size and number of stages for multistage pumps. Pdf characteristics of centrifugal pumps working in direct. Centrifugal pump classification number of stages single stage multistage shaft position horizontal vertical horiz. Operational characteristics of a centrifugal pump engineers.
A typical composite curve includes the pump performance curves, horsepower curves and npsh required. The possible combinations of total pressure and volume flow rate for a specific pump can be plotted to create a pump curve. Reading and understanding centrifugal pump curves is key to proper pump selection, and to their reliable and efficient operation. This tech brief examines how pump curves can provide data about a pump s ability to produce flow against certain head, shows how to read a typical centrifugal pump curve. The centrifugal pump characteristic curves show the law and. Inside a centrifugal pump, an impeller rotates on a drive shaft. The operating point adapts itself to the intersection point of these two lines in dependence of pump characteristic curve and system characteristic curve automatically see diagram 5 24. Checklist of problems vvith centrifugal pumps and their causes centrifugal pumps are one of the worlds most commonly used devices. Invented in the 17th century, the basic principle is still used today.
Pdf laboratory report centrifugal pump anh phuong le. Components of centrifugal pump performance curve 1. Whats the significance of pump characteristic curves. The operating characteristic of a pump at a speed of 1430 revmin and a rotor diameter of 125. Theory one way of illustrating pump characteristics. Jordan, an application engineer at crane engineering, explains how to read a centrifugal pump curve in the video below. Centrifugal pump curves characteristics continued bhp brake horsepower and capacity for the centrifugal pump to deliver the capacity we want, we must supply the pump with a certain hp. For prerotation control, the impeller is preceded by controllable inlet guide vanes.
The choice of pump for a given application depends largely on how the pump headflow characteristics match the requirement of the system downstream of the pump. Pump and system curves the pump curve is solely a function of the physical characteristics of the pump. When sizing, it is helpful to select a pump whose curve puts the duty point as close to this bend in the curve. Session 1 system curves alabama water environment association. Pump cavitation is caused by the reduction in system heads. The impeller accelerates the flow of the fluid handled. Centrifugal pumps pump curves real pumps are never ideal and the performance of the pumps are determined experimentally by the manufacturer and typically given in terms of graphs or pump curves. To change the operating point either the system curve or the pump curve. These are graphed for fixed pump speed for each impeller diameter in a given family of pumps. A centrifugal pump converts driver energy to kinetic energy in a liquid by accelerating the fluid to the outer rim of an impeller. For the normal operating range of centrifugal pumps n, q and h all positive, it is sufficient to plot the characteristic curve in the first quadrant of the hq coordinate system.
Centrifugal pump characteristic curve components of centrifugal. Pump manufacturers use the terminology called head and pump users use pressure to measure the performance. When sizing, it is helpful to select a pump whose curve puts the duty point as close to this bend in the curve as possible. Checklist of problems vvith centrifugal pumps and their causes. Typical performance curves for a single impeller speed and diameter appear as. To read pump system curve and operating points click here. Pump performance charts with multiple pump curves are shown below. Flow, head, impeller trim diameter, efficiency, power, npshr, mcsf minimum continuous stable flow and rpm. Characteristic curves for a singlestage centrifugal and other components. The curve begins at the point of zero flow, or shutoff head, and gradually descends until it reaches the pump runout point or maximum flow rate. All energy transferred to the fluid is derived from the mechanical energy driving the impeller.
The twophase model is solved numerically in the case of a radial. The following figure shows typical performance curve for a centrifugal pump related to the system frictional head. The flow rate q and the developed head h are both determined by the intersection. In industry, characteristics of all pumps are usually read from its qh curve or performance curve flow rate height. Centrifugal pump characteristic curve for an operations engineer who is working in a chemical process industry or a process engineer who is involved in hydraulic calculations understanding the centrifugal pump performance curve is an important aspect. Sep 24, 2018 centrifugal pump curves show 8 important factors that are critical in selecting the right pump for your application. Pdf characteristics of centrifugal pumps working in. Pdf centrifugal pump performance characteristics for domestic. The most efficient point of two curves is illustrated in figure 1.
May 03, 2018 before we start first we will understand the basics of centrifugal pump performance curve. Timar department of chemical and biochemical engineering, faculty of chemical and food technology, slovak university of technology, sk812 37 bratislava email. How to read a pump curve for centrifugal pumps pumpworks. During operation of a pump, the pump must run constantly with the speed of the prime mover. Positive displacement pumps have a constant torque characteristic, whereas centrifugal pumps demonstrate variable torque characteristics. Figure 12 shows the characteristic curve of an actual pump a single stage vertical turbine pump together with the characteristic curve of the process, known as the system curve. How to read a centrifugal pump curve crane engineering. Pdf water pressure problems at home can be quite frustrating in daily life. Depending on the required delivery head, the centrifugal pump will find its operating point when the plant curve and pump curve meet. Unlike positive displacement pumps such as piston pumps, centrifugal pumps deliver a var iable flow rate q increasing. Centrifugal pump monitoring and determination of pump. Centrifugal pump curves for various specific speeds.
Pump head, on the vertical axis, is the difference between system back pressure and the inlet pressure of the pump. To do that, an engineer would refer to a pumps composite curve. Pdf laboratory report centrifugal pump anh phuong le vu. The operating point of a centrifugal pump, also called its duty point, is given by the intersection of the pump characteristic curve with the system curve. For example, a 350 mw unit would require two feedpumps in parallel. A centrifugal pump performance curve is a tool that shows how a pump will perform in terms of head and flow. Generally, the hp increases as we increase the capacity. Dimensionless characteristics of centrifugal pump p. The performance or characteristic curve of the pump. Understanding of centrifugal pump performance curve is very important for select a proper pump for the required application. Unit 571 new smyrna beach, fl 32128 386882ezce3923. Reading centrifugal pump curves national environmental. Most centrifugal pumps are characterized by an elliptical head curve which is at a maximum at zero flow shut off and a minimum at run out.
A pump performance curve indicates how a pump will perform in regards to pressure head and flow. Centrifugal pump performance curves and technical information. The operating characteristic of a pump at a speed of 1430 revmin and a rotor diameter of 125 mm is as follows. A common application of the multistage centrifugal pump is the boiler feedwater pump. Maximum normal capacity line should not operate in the region to the right of the line because pump can be unstable. How it operates in practice is determined by the resistance of the system it is installed in.
Jordan, an application engineer at crane engineering, explains how to read a centrifugal pump curve. A centrifugal pump is required to produce a flow of water at a rate of 0. Centrifugal pumps are commonly used to move liquids through a piping system. As can be seen, the performance charts use a discharge q usually in m 3 h and pump. The centrifugal force moves the fluid towards the outer edge of the pump. Positive displacement pumps are those in which energy is imparted to the liquid in a fixed displacement volume, such as a casing or a cylinder, by the rotary motion of gears. Theory one way of illustrating pump characteristics is to construct contour lines of. Lesson 28 characteristic curves of centrifugal pumps. These curves are observed to have the following characteristics.
Centrifugal pump selection michael smith engineers. Characteristics of centrifugal pumps working in direct or reverse mode. How to select a centrifugal pump examples of total head calculations sizing a pump. Affinity laws applied to centrifugal pump applications. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially. The headdischarge curve hq curve relates the head produced by a pump to the volume of water pumped per unit time i. A curve is defined for a specific operating speed rpm and. To create head, power and efficiency characteristic curves for a centrifugal pump. A pump curve denotes flow on the xaxis horizontal and head pressure on the yaxis vertical.
Pumping head characteristic curves are plots of what an existing pump can do under various loads duties we measure the pump characteristic curve by determining. Usually the operating point is not on the qh curve of the pump. How to read a centrifugal pump performance curve mechanical. The pump curve describes how a centrifugal pump performs in isolation from plant equipment. From there you can adjust operating speeds, viewsave electronic curves and data sheet reports in a pdf format, generate system curves, simulate multiple pumpsspeeds, request quotes and much more. Characteristic curve pumps, valves and service ksb. The system curve is completely dependent on the size of pipe, the length of pipe, the number and location of elbows, and other factors. Operational characteristics of a centrifugal pump normally, a centrifugal pump produces a relatively low pressure increase in the fluid. Centrifugal pump characteristic curve components of. This tech brief examines how pump curves can provide data about a pump s ability to produce flow against certain head, shows how to read a typical centrifugal pump curve, and provides.
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