Application of the energy equation between the two free surfaces, points 1 and. The energy transfer in a centrifugal pump is accomplished by changing the state of motion of the liquid. From the above equation it follows that the system characteristic curve shifts vertically in the hq sys coordinate system if the systems tank pressures pa, pe and the geodetic head h geo z a z e vary. First of all, the complete characteristics head, power, and efficiency were measured experimentally using a specific test loop. 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. 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. Download practical centrifugal pumps design, operation. The single most energy efficient discharge versus head point on the pump curve is termed as the best efficiency point bep. Certrifugal pump reciprocating pump schematic diagram characteristic curve is essential. A group of empirical equations were developed in order to estimate the performance curves h q, n q, p q, npshr q of a centrifugal pump. But for a specific operation there exists a head vs discharge equation depending on the system characteristics. A typical centrifugal pump characteristic curve is shown below. It is evident from this figure that for a typical radial flow pump, npshr gradually increases as the pump discharge increases. Depending on the required delivery head, the centrifugal pump will find its operating point when the plant curve and pump curve meet.
Ratio of power output of the pump to power input to the pump or shaft. To do that, an engineer would refer to a pumps composite curve. Only the head and flow information is displayed on the pump curve. Lesson 28 characteristic curves of centrifugal pumps. Figure 4 shows a typical head, h ft, versus capacity discharge, q gpm, curve for a singlestage. Reading and understanding centrifugal pump curves is key to proper pump selection, and to their reliable. Both may be freely downloaded from the appropriate organisation website see below. Reading and understanding centrifugal pump curves is key to proper pump. Pdf dimensionless characteristics of centrifugal pump. The most efficient point of two curves is illustrated in figure 1. In this case it is the p1value that has to be taken into account.
Oct 27, 2016 in simple terms, a pump is a mechanical device, used to lift water fluid from low level to high level. When viewing the calculated results, the pump operating point the red knee is displayed on the pump curve. The present experimental study deals with the effect of varying different soft slurry concentrations ranging from 0 to 18 % by weight on the performance characteristic of a centrifugal pump. The h in the curve is the difference in energy level between the suction and the pressure side of the pump. Performance characteristics of centrifugal pump conveying soft slurry. Understanding centrifugal pump curves when selecting a centrifugal pump, one should match the performance of the pump to that needed by the system. Baldoukas department of mechanical engineering, tei of halkida, 34 400 psachna, greece abstract. Whats the significance of pump characteristic curves. On xy plot, head is plotted in y axis and the flow is plotted in x axis. Each pump has its own pump performance curve, and what might be the perfect pump for one particular situation may be totally wrong for another. Azouz 2, 1 department mechanical engineering, faculty of engineering, lebanese international university, beirut, lebanon. Frequency reference speeds for the characteristic curve documen. Smaller impellors produce less pressure at lower flow rates.
Details about centrifugal pump characteristic curve. Curve captor is a free distributed under gpl vacuum tube modeling software that brings the advantages of modern computer simulation tools to design of vacuum tube curve captor is a free distributed under gpl vacuum tube modeling software that brings the advantages of modern computer simulation tools to design of vacuum tube electronics. In simple terms, a pump is a mechanical device, used to lift water fluid from low level to high level. Understanding centrifugal pump curve chemical engineering site. Pump characteristic curves manufacturer of a pump supplies a curve that shows head obtained by the pump for different discharge values. Pump performance charts with multiple pump curves are shown below. For the pump project assignment, use the measured data for your pump. Grundfos has developed the pump handbook, which in a simple manner deals with various considerations. In simple terms, a pump curve is a graphical representation of the performance characteristics of a pump. Shutoff head is the maximum head that can be developed by a centrifugal pump operating at a set speed. Pump runout is the maximum flow that can be developed by a centrifugal pump without. Centrifugal pump characteristic curve components of. Performance characteristics of centrifugal pump conveying.
At each pump curve intersection, the flow and tdh is fixed. Understanding centrifugal pump curves allied pumps. For example, in figure 10, the operating point for the centrifugal pump in the original system is designated by the intersection of the pump curve and the system curve h lo. The flow rate q and the developed head h are both determined by the intersection. The system characteristic curve see characteristic curve represents the relationship between the system head h sys and the flow rate q.
Overal pump performance and unsteady pressure pulsation information are. Shut off head is the head developed by the pump at zero flow. Characteristic curves for a singlestage centrifugal and other components. Centrifugal pump curves formats engineered software. Energy is imparted to the liquid by means of a disk with curved vanes. Selecting a centrifugal pump by system analysis 2012 instructor.
A comparative study on centrifugal pump designs and two. By graphing a system characteristic curve and the pump characteristic curve on the same coordinate system, the point at which the pump must operate is identified. Practical centrifugal pumps design, operation and maintenance by the authors paresh girdhar, moni is a comprehensive guide to pump construction, application, working, maintenance and management issues. Pump curves may include additional information about required horsepower input, pump efficiency and net positive suction head required, referred to as npshr. The numerical data obtained from a cfd study performed with the ansys cfx software and based on steady state and. Usually the operating point is not on the qh curve of the pump. Pump manufacturers use the terminology called head and pump users use pressure to measure the performance.
The characteristic curves of centrifugal pumps plot the course of the following parameters against flow rate q. A typical composite curve includes the pump performance curves, horsepower curves and npsh required. To change the operating point either the system curve or the pump curve must be changed. Centrifugal pump characteristic curve engineers edge. The same goes for the efficiency value, which only covers the pump part. Use either of the following equations to determine the new ed or use equations involving d to determine the trim pump characteristic curve 4.
Prediction of performance characteristics of a centrifugal. Performance curves for a twostage centrifugal pump operating at 3500 rpm. Centrifugal pump performance curves and technical information. Fundamentals of fluid mechanics chapter 12 pumps and.
Plot the values from this table on the graph that already has the the pump characteristic curve the equal efficiency curve, and determine the q3 and h3 5. Components of centrifugal pump performance curve 1. The main advantage of this approach is the fact that only one characteristic curve is used for all possible operating speeds of the tested pump in the frame of suitable dimensionless numbers. Jun 27, 2018 failure to do so can drastically reduce the service life of pump components.
Reading and understanding centrifugal pump curves is key to proper pump selection, and to their reliable and efficient operation. The figure below shows a typical pump curve as furnished by a. In some pump types with integrated motor and perhaps also an integrated frequency converter, e. 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 characteristic curve is a componentspecific plot that shows how a change in one dynamic variable might affect others. Pump and motor characteristic curves what are characteristic curves. Different pumps that operate with different pump curves will all operate along the system curves but at different fixed points. The magnitude of this change depends upon the dimensions and shape of the waterways and on the operating speed of the impeller. 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.
Versatility is one of the main characteristics of neptuno pumps vtp. 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. Qh curves will be given by the manufacturer of the pump and can normally be considered as a simple quadratic curve. Characteristics of centrifugal pumps working in direct or. The required horsepower input to a pump and the efficiency of that pump depends on where on the pump curve the pump is operating. Types, performance evaluation, efficient system opera tion, flow control. B closed pressure vessel with free flow from the pipe ending above the water level. The manually entered pump curve has a lower amount of pump data entered, but it also has less operating data displayed on the pump curve. The hydraulic properties of a pump can be described by some characteristics. This pressure is expressed in units of measure called pounds per square inch psi or feet of headft. Publication date 1921 topics pumping machinery publisher. It is often parabolashaped and does not generally pass through the origin of the hq coordinate system. There are several terms associated with the pump characteristic curve that must be defined. On the centrifugal pumps performance curves estimation using empirical equations n.
Each pump has its own pump performance curve, and what might be the perfect pump for one particular situation may be totally wrong for. Where these curves cross is the operating point see figure 3. Experimental and numerical investigations have been carried out to study the behaviour of a centrifugal pump operating in direct mode or turbine mode. 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. Jordan, an application engineer at crane engineering, explains how to read a centrifugal pump curve in the video below. Download practical centrifugal pumps design, operation and. The fourth characteristic curve typically published by pump manufactures is the net positive suction head required npshr versus pump discharge q curve as shown in fig. The reason for the system curves parabola shape becomes clear. How to read a centrifugal pump curve crane engineering. Reading centrifugal pump curves national environmental.
On the manual pump curve data entry, you enter the pump performance data on the pump dialog box under the curve tab. Such curves capture the performance of a component over a range of operating conditions and are commonly used in component selection, sizing, and analysis. On the centrifugal pumps performance curves estimation using. Knowing how to read a centrifugal pump curve is essential to the health of your system.
The characteristic curves shape is primarily determined by the pump type i. Experimental results are presented for pump performance head, overall efficiency and electrical power input as a function of the flow rate. Technically, it is a contrivance which provides energy increases both kinetic or potential to the fluid by transforming the mechanical energ. Apr 08, 2016 plot the values from this table on the graph that already has the the pump characteristic curve the equal efficiency curve, and determine the q3 and h3 5. 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. For a given pump geometry and operating speed, the velocities of the liquid vary with the flow rate. In addition the pump performance is predicted by general. 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. Centrifugal pump curve freeware free download centrifugal. 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. A performance curve is used to determine which pump best. Publication date 1921 topics pumping machinery publisher london. 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. A typical characteristic curve shows the total dynamic head, constant horsepower, efficiency, and net positive suction head all plotted over the capacity range of the pump.
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