These curves are also utilized as starting blocks for the design and selection of pumps to arrive at an efficient outcome. While there are dozens, even hundreds, of different centrifugal pump designs, virtually all of them can be categorized into just a few categories. A centrifugal pump is a very simple device, mechanically. Centrifugal pump curves for various specific speeds. The efficiency of centrifugal pumps varies over the individual curve. To read pump system curve and operating points click here. Even agreeing on a basic definition for minimum flow can be problematic. The centrifugal pump operation should conform to the pump curves supplied by the manufacturer. If a pump is offered with multiple impellers with different diam eters, manufacturers typically plot a separate pump curve for each size of impellor on the same pump performance chart. A typical composite curve includes the pump performance curves, horsepower curves and npsh. Rotodynamic or simply dynamic pumps impart momentum to a fluid, which then causes the fluid to move into the delivery chamber or outlet.
In order to read and understand the pump curves, it is very important to develop a clear understanding of the terms used in the. Back to basics w hen i left university, i found that i needed additional information to turn my theoretical knowledge of fluid mechanics into the practical knowledge required to specify a pump. Pump curves for hydronic circulators always show the head energy added along the vertical axis and the flow rate through the circulator on the horizontal axis. Centrifugal pumps have much different horsepower input characteristics than positive displacement pumps. The inline design of the pumps enables installation in a horizontal onepipe system. Understanding centrifugal pump curves allied pumps. A drooping pump curve is a characteristic headflow pump performance curve that does not continually rise when moving from the best efficiency point bep back to shutoff. Pump the cr pump is a nonselfpriming, vertical multistage centrifugal pump. 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. These curves are generated by pump manufacturers for each specific pump type. It consists of an impeller that is attached to a shaft which is rotated by a driver, most often by an electric motor. If we take the operating point b we can determine point c. Pdf centrifugal pump handbook, third edition sulzer.
If flow were completely frictionless, a centrifugal pump would be 100% efficient. In simple terms, a pump curve is a graphical representation of the performance characteristics of a pump. To do that, an engineer would refer to a pumps composite curve. Centrifugal pumps are commonly used to move liquids through a piping system. 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. Fortunately, manufacturers include this information on the curves as well.
This portable document format \ pdf \ file contains bookmarks, thumbnails, and hyperlinks to help you navigate through the document. Aug 26, 2017 the centrifugal pump curve has high and low flow limits, which can cause significant mechanical damage to the pump if not avoided. Checklist of problems vvith centrifugal pumps and their causes. What is total head 10 what is the relationship between head and total head 11. Castle pumps performance curves are based on the actual motor rpms that are used, whereas some manufacturers round up the rpms to the nearest thousand making the curve less accurate. Lesson 28 characteristic curves of centrifugal pumps.
Reading and understanding centrifugal pump curves is key to proper pump selection, and to their reliable and efficient operation. Reading centrifugal pump curves national environmental. Understanding centrifugal pump curve chemical engineering site. How to read a pump curve for centrifugal pumps pumpworks. 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. Before we start first we will understand the basics of centrifugal pump performance curve. Understanding centrifugal pump curves when selecting a centrifugal pump, one should match the performance of the pump to that needed by the system. Each pump has its own pump performance curve, and what might be the perfect pump for one particular situation may be totally wrong for. The fluid must be available to the pump with sufficient energy so that the pump can work with the fluids energy. Q curve can be plotted based on measured values from combination of hq curve and pq curve and this formula. Pump curves relate flow rate and pressure head developed by the pump at different impeller sizes and rotational speeds. Pump cavitation is caused by the reduction in system heads.
California state polytechnic university, pomona mechanical engineering department memorandum to. In centrifugal pumps the delivery head h depends on the flow rate q. Pump iso efficiency and other curves every pump manufacturer generates pump curves for every type of pump to define. Close contact with the market has opened up new fields of application. This new edition of the centrifugal pump handbook takes full account of the recent progress that has been made in pump construction and technology. Pumps can generate high volume flow rates when pumping against low pressure or low volume flow rates when pumping. The limits of the centrifugal pump curve turbomachinery. Make no mistake, theres a lot of information on a centrifugal pump curve like the one shown here. From munson et al, fundamentals of fluid mechanics figure 7. Fluid mechanics centrifugal pump performance experiment. Pumps are designed and selected to operate near their highest efficiency point.
The pump curves start at a high point on the left side of the graph called the shut off head. Technical data on this page are grouped by pump type, and listed by pump model number. Centrifugal pump selection michael smith engineers. Berkeley type b end suction centrifugal pumps 3600 rpm. Centrifugal pump performance curves and technical information 0 20 40 60 80 100 120 140 0 10 20 30 40 50 60 70 80 0 100 110 capacity ead ft nps in feet 10 20 30 40 50 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 160 npsh req u i r e d 2 5 0 m i mp e l r dia t r 9 16 45 h e a d c a p a c i t y 0 5 10 15 20 25 30 35 40 gpm lbs. Product data introduction this data booklet deals with grundfos cr, cri and crn as well as cre, crie and crne pumps. A comparative study on centrifugal pump designs and two. Fluid mechanics centrifugal pump performance experiment 1. The manufacturers pump curves use pump operating data entered, checked, and supplied by the manufacturer of the pump. S200 series stainless steel centrifugal pumps waukesha.
Unlike positive displacement pumps such as piston pumps, centrifugal pumps deliver a var iable flow rate q increasing. More specifically, two pumps are said to be homologous if they are geometrically similar and the following two dimensionless parameters are the same. A centrifugal pump is required to produce a flow of water at a rate of 0. They are normal curves, flat curves and drooping curves. Running too far out on the curve, or too far back, can cause damage to the pump, excessive energy consumption, and overall poor performance. 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. Head versus capacity power versus capacity npsh versus capacity.
The performance or characteristic curve of the pump. You will notice in the above curve that the pump is being operated at 2940rpm 3000rpm so this curve is for a pump operating at 50hz. The efficiency curve is used for choosing the most efficient pump in the specified operating range. Waukesha cherryburrell wcb curves are intended for use as an aid for preliminary selection of pumps by trained and qualified engineers. In a normal curve the head decreases rapidly as flow increases. Jun 27, 2018 failure to do so can drastically reduce the service life of pump components.
Taco radiant made easy application guide technical documents. Dec 07, 2014 fluid mechanics centrifugal pump performance experiment 1. Curves relating total head, efficiency, power, and net positive suction head required npshr to discharge or pump capacity q are utilized to describe the operating properties characteristics of a 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. Some curves are drawn to show the performance of several impeller diameters from the maximum impeller to the minimum impeller. Pdf dimensionless characteristics of centrifugal pump. 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. The centrifugal pump characteristic curves show the law and. To change the operating point either the system curve or the pump curve must be changed. This paper addresses the influence of airwater twophase mixture on the characteristic curve of a centrifugal pump. Reading the centrifugal pump curve, however, is a different story. A characteristic curves selection chart is the graphic representation of several characteristic curves which shows the effect of various changing parameters on machines in one diagram. 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. When plotted on the same graph, the point at which the system curve and pump curves intersect is called the operating point it identifies the capacity you can expect from the pump.
Dont run centrifugal pumps on the end of the curve. Centrifugal pump monitoring and determination of pump. Pdf laboratory report centrifugal pump anh phuong le. The performance of a centrifugal pump is shown by a set of performance curves. Checklist of problems vvith centrifugal pumps and their causes centrifugal pumps are one of the worlds most commonly used devices. A definition that at first glance seems more than reasonable is as follows. The lowest pump flow that can be maintained continuously. Pdf centrifugal pump performance characteristics for domestic. Scroll down, find the model number of your pump, and click the link to open the. How to read a centrifugal pump curve simscale blog. The concept of the fluid being available to the pump is discussed in detail in chapter 2 of this book. Pump performance charts with multiple pump curves are shown below.
In some cases an additional pressure behind the impellers to the point that the. Centrifugal pumps are widely used in industrial and domestic situations. During a bench test, the pump is operated at constant speed and the values q and h are. Mtrspkmthmta multistage centrifugal pump cooling lubricants. Pump efficiency is the ratio of the energy imparted by the pump to the energy required by the pump.
The performance curves for a centrifugal pump are shown in figure 1. How to read a pump curve years ago, making a pump selection meant sitting down with large printed catalogs and flipping through them until you reached a pump curve that fit a projects hydraulic requirements. If they operate at the righthand end of the pump curve the likelihood of cavitation increases. Understanding of centrifugal pump performance curve is very important for select a proper pump for the required application. Ksb aktiengesellschaft has been manufacturing centrifugal pumps for more than 110 years. Cornell pump company centrifugal pump curve classifications. Centrifugal pump curves estimate pump performance at different impellor diameter and speed based on affinity laws. Centrifugal pump performance test inspection for industry. The efficiencyflowrate curve at centrifugal pump performance test. Based on the combination of pressure lift and volume flow a classification of pumps can be made, which can be quantified with the specific. Pump category subcategory distillation hydrotreating hydrocracking catalytic cracking residuum and heavy oil upgrading gas treating and sulfur recovery lng ngl and lpg gas to liquids offsites and waste treatment heavy oil, oil sands and shale crude, product and co. The pump casing shall be vertically split, end suction, top.
Oct 01, 20 ron astall, united pumps australia ask ten different pump engineers for their guidelines on establishing centrifugal pump minimum flow and you might get ten different answers. Its no wonder that many newly practicing engineers are a little inti. The operating characteristic of a pump at a speed of 1430 revmin. By learning about these common types of centrifugal pumps, youll be better prepared to make a pump type recommendation the next time you assist with the pump design and selection process. At the low flow end of the curve, flow recirculation can damage a pump, while at the high flow end, excessive npshrequired, horsepower and choke flow can result in mechanical damage to impellers, casing, shaft, bearings and seals. The pump cannot suck on or draw the liquid into the pump. Centrifugal pump performance curves and technical information. This set of four curves is known as the pump characteristic curves or pump performance curves. Centrifugal pump curves formats engineered software. This tells us how much energy is lost by the pump mechanism. Centrifugal pumping is the terminology used in the management of water and other fluid. Smaller impellors produce less pressure at lower flow rates.
The pump curve describes the relationship between the rate of fluid flow and head for the pump itself. This is a family of parabolic curves starting at the origin. Depending on the required delivery head, the centrifugal pump will find its operating point when the plant curve and pump curve meet. Examples of such parameters are the impeller diameter see impeller trimming, preswirl control see figs.
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. How to read a centrifugal pump curve crane engineering. Pump curves are drawn showing the performance of the rated impeller diameter. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially.
The manual pump curve displays the minimal information, showing only the pump head as a function of flow rate. The chamber stack and the outer sleeve are secured between the pump head and the base by means of staybolts. Jordan, an application engineer at crane engineering, explains how to read a centrifugal pump curve in the video below. We consult pump curves not only to see if they can do the work we need them to do but if they will do it efficiently. Centrifugal pump impellers can be machined to larger or smaller diameters to alter the performance to best match the application. Product data 3 introduction 3 performance range of cr, cri, crn 4 performance range of cre, crie, crne 4 applications 5 product range 6 pump 8 motor 8 terminal box positions 9 ambient temperature 9 viscosity 9 2. The wrong pump will not only operate inefficiently, but can fail prematurely because it is not ideally suited to the applications conditions. Turbines and centrifugal pumps all fall into this category.
A 316 stainless steel shaft shall be furnished in all pumps. Components of centrifugal pump performance curve 1. Pdf water pressure problems at home can be quite frustrating in daily life. The base has suction and discharge ports on the same level inline. With the exception of the shaft and bearings, there is. Grundfos pumps ltd grovebury road leighton buzzard beds lu7 4tl. How to select a centrifugal pump examples of total head calculations sizing a pump for a home owner application 14. Now, decide on the curve that best suits the application of desired gpm, head feet, and rpm.
Cornell pump company manufactures closecoupled and frame mounted centrifugal pumps for the agriculture, food processing, industrial, refrigeration, municipal, rental oem, mining, and oil and gas markets. This tech brief examines how pump curves can provide data about a pumps abili. Head is a measurement of the height of the incompressible fluid column the pump could create from the kinetic energy, that the pump gives to the liquid. Knowing how to read a centrifugal pump curve is essential to the health of your system. Jun 26, 2014 knowing how to read a centrifugal pump curve is essential to the health of your system. Head, power consumption, efficiency and npsh are shown as a function of the flow. The centrifugal pump performance curve consists of four set of curves. The ksb group exceeds the energy saving objectives of future eu regulations, which translates into large savings for the groups customers. Judging by the questions i see asked nearly every week on linkedin and elsewhere, i believe this is a problem shared by many engineers early in. The possible combinations of total pressure and volume flow rate for a specific pump can be plotted to create a pump curve. The pump is to be furnished with 58 type 21 mechanical seal with stainless steel metal parts, viton elastomers, ceramic seat and carbon washer.
The corresponding theoretical head coefficient curves are presented in figure 12. Know and understand centrifugal pumps \ r i \ suction piping. This relationship, also called pump performance, is illustrated by curves. The varous pump curves are provided by the pump manifacturer. Reading and understanding centrifugal pump curves is key to proper pump selection. Choosing the correct centrifugal pump for your application is critical for maximizing longterm performance. Berkeley type b end suction centrifugal pumps are ideal for applications that require high performance, easy maintenance and moderate initial cost, used in many oem, industrial, commercial, swimming pool, and agricultural applications. Pipeflo can select pumps directly from the supplied electronic pump catalog. Berkeley type b end suction close coupled centrifugal pumps. In fluids dynamics the term pump head is used to measure the kinetic energy which a pump creates. Find your local representatives within your region for product inquiries. A typical composite curve includes the pump performance curves, horsepower curves and npsh required.
668 1467 982 359 1079 247 871 219 16 380 449 805 1235 214 823 710 797 713 1287 621 1278 1409 1039 1317 434 460 1337 415 549 1431 267 621 704 1211 349 114 783 899 1155 837 1085 214 1404 1092 1428 1186 636 314 209 1047