Reading and understanding centrifugal pump curves is key to proper pump selection, and to their reliable and efficient operation. Each graph will usually have curves representing the pump head vs. Data for these curves are developed by testtem head. When reading pump curves, simply type in your duty point or just click directly on the graph and compare it to the pump curve. Section 3 describes basic terms and concepts regarding the operation and performance of positive displacement pumps.
Certrifugal pump reciprocating pump schematic diagram characteristic curve is essential. For any flow, there is a range of pump lifts required. Centrifugal pump characteristic curve pump performance. 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.
This set of four curves is known as the pump characteristic curves or pump performance curves. Pump manufacturers use the terminology called head and pump users use pressure to measure the performance. 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. Components of centrifugal pump performance curve 1. The pump curve also displays the pump model, the pump size and number of stages for multistage pumps.
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. The pump performance curve describes the relation between the flowrate and the head for the actual pump. Centrifugal pump monitoring and determination of pump characteristic curves using experimental and analytical solutions article pdf available in processes 62. Lesson 28 characteristic curves of centrifugal pumps. Positive displacement pumps have a constant torque characteristic, whereas centrifugal pumps demonstrate variable torque characteristics. The curves for power consumption and efficiency will normally only cover the pump part of the unit i. Characteristic curves of centrifugal pumps are defined as those curves which are plotted from the results of a number of tests on the centrifugal pump.
Section 2 contains tables of information useful for pump sizing. The characteristic curves of centrifugal pumps plot the course of the following parameters against flow rate q. Versatility is one of the main characteristics of neptuno pumps vtp. Pumps of dissimilar characteristics can operate in parallel, if the system head does not exceed the shut off head of any of the pump at any. Qh characteristic diagram of centrifugal pump and of pipeline. Examples of such parameters are the impeller diameter see impeller trimming, preswirl control see figs. Gather all application information including product nature, viscosity, temperature, nipa, flow rate and pressure loss. The h in the curve is the difference in energy level between the suction and the pressure side of the pump. However, as the pump characteristic is changing, the control system needs to know how to adjust the pumping parameters accordingly, so that the pump runs under safe conditions. Reading centrifugal pump curves national environmental. Pump efficiency and power pump efficiency, epump pump water horsepower whp e brake horsepower bhp 221 n by the pump manufacturer calculate required bhp, knowing epump water horsepower is defined as. The characteristic curves flowhead of the pump were determined by measuring the difference between the outlet and the inlet pressures for different steady flow rates. Pump characteristic curves also offer the opportunity to establish the optimum solution to operate the pumppumps at or closest to the bep as well as ascertain the implication of operating away from the bep.
How to read a centrifugal pump curve crane engineering. In some cases an additional pressure behind the impellers to the point that the. A centrifugal pump converts driver energy to kinetic energy in a liquid by accelerating the fluid to. The pump performance curves are based on data generated in a test rig. The modules listed in the overview are linked to the corresponding pages. This portable document format \ pdf \ file contains bookmarks, thumbnails, and hyperlinks to help you navigate through the document. To do that, an engineer would refer to a pumps composite curve. The operating point of a pump is determined by the intersection of the pump and system curves. 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 flow rate q and the developed head h are both determined by the intersection. The curves were plotted for various values of the rotating speed.
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. A pump performance curve indicates how a pump will perform in regards to pressure head and flow. This lecture is all about centrifugal pump characteristic curves, npsh available and npsh required. Flow, head, impeller trim diameter, efficiency, power, npshr, mcsf minimum continuous stable flow and rpm. Actual pump performance data will typically be presented graphically as shown in fig. Centrifugal pump exercise b objective to create head, power and efficiency characteristic curves for a centrifugal pump. Pump characteristic curves in most pump curves, the total dynamic head h in m ft, the efficiency e in percent, and the power input p in kw hp are plotted as ordinates against the flow 3 rate q in m3sormh galmin or mgald as the abscissa. Pdf laboratory report centrifugal pump anh phuong le. Theoretical study and measurement of the characteristic. Qh curves will be given by the manufacturer of the pump and can normally be considered as a simple quadratic curve. Each of the characteristics is explained in the next sections for propeller pumps. Velocity head is calculated using the ing several pumps of a specific model.
Centrifugal pump monitoring and determination of pump. Selecting a positive displacement pump using performance curves choosing a pump series a. 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. Understanding centrifugal pump curves when selecting a centrifugal pump, one should match the performance of the pump to that needed by the system. Centrifugal pump curves show 8 important factors that are critical in selecting the right pump for your application. To determine the form of a system curve, consider the equation for total pressure in a piping system. Unlike positive displacement pumps such as piston pumps, centrifugal pumps deliver a var iable flow rate q increasing. Qh curves will be given by the manufac turer of the.
A centrifugal pump performance curve is a tool that shows how a pump will perform in terms of head and flow. Pdf dimensionless characteristics of centrifugal pump. A typical composite curve includes the pump performance curves, horsepower curves and npsh required. You can also do quick calculations on efficiency, speed and p1. Whats the significance of pump characteristic curves. This also keeps the spare part inventory to an economic level 2. This paper shows the concept of how the pump characteristic curves transform from the normal state to the conditions of circulating a twophase mixture. The graphs will also show curves of constant efficiency and constant pump power bhp. 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. The efficiency of centrifugal pumps varies over the individual curve. The following figure shows typical performance curve for a centrifugal pump related to the system frictional head.
Pumping system curves michigan technological university. Pumps and pumping system bureau of energy efficiency 116 figure 6. These curves are necessary to predict the behaviour and performance of the pump when the pump is working under different flow rate head and speed. The characteristic curve s shape is primarily determined by the pump type i. Learn about pump characteristic curve in this excerpt from the pumps and motors lecture from our distribution exam prep course. Pump cavitation is caused by the reduction in system heads. 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. To change the operating point either the system curve or the pump curve must be changed. A centrifugal pump requires a minimum amount flow to be moving through the pump to dissipate heat created.
Section 1 contains the technical information including. 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. The total pressure caused by a piping system is the sum of. For systems pump manufacturers normally publish a set of with a high total head this component is very small characteristic curves for each pump model they compared with other components of the total sys make.
Pump body strainer impeller shaft mechanical seal aluminum cast iron on request aluminum cast iron on request stainless steel aisi 304 on request. Centrifugal pump characteristic curve components of centrifugal. What follows is a brief presentation of the different pump performance curves. Pdf centrifugal pump monitoring and determination of. Explain the performance and characterstic of centrifugal pumps.
Pump head, on the vertical axis, is the difference between system back pressure and the inlet pressure of. 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. 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. In a piping system, pressure loss due to friction increases with increasing fluid flow. Pump curves are a diagnostic tool, for establishing pump performance in an operating system. Selecting a positive displacement pump using performance. Other important information for a proper pump selection is also included like efficiency curves, npsh r curve, pump curves for several impeller diameters and different speeds, and power consumption. Characteristic curves a type performance data b type 0 200 0 12 25 20 15 10 5 0 total head hm 9 15 18 lmin qm3h 50 100 150 250 300 350 qdx7180.
Theory one way of illustrating pump characteristics is to construct contour lines of. On the left side of the curve, minimum flow is indicated by a vertical bold line. A curve is defined for a specific operating speed rpm and. A vendor manual for a specific pump usually contains a curve of pump flow rate versus pump head called a pump characteristic curve. For example, on the curve for 308 mm impeller, one duty point is. Selecting identical pumps as far as possible with stable qh characteristic for equal load on each pump. Pdf centrifugal pump monitoring and determination of pump. Centrifugal pump characteristic curve components of. After a pump is installed in a system, it is usually tested to ensure that the flow rate and head of. Pump characteristic an overview sciencedirect topics. In general, pump curves are designed according to iso 9906 annex a, which specifies the tolerances of the curves.
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