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. It isconcluded that the leakage lossplays a major role inthe performance of a centrifugal slurry pump. Components of centrifugal pump performance curve 1. Detailed performance of radialbladed centrifugal pump. Centrifugal pump pump curves pumps can generate high volume flow rates when pumping against low pressure. What follows is a brief presentation of the different pump performance curves. To determine the performance data at a particular point, first locate the operating point of the pump. In fluids dynamics the term pump head is used to measure the kinetic energy which a pump creates.
Actual on site performance will be given by the intersection of the pump curve with the actual system curve. Let us look again at examples of stable and unstable pump curves. Pdf water pressure problems at home can be quite frustrating in daily life. This tells us what the pump is capable of flowing if we fulfill the other inputs. 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 performance experiment the purpose of this experiment was to determine the performance. Follow the pressure line, down and to the right, until it intersects 3 the product viscosity 2. Pdf centrifugal pump performance drop due to leading. Pump performance curve a centrifugal pump performance curve is a tool that shows how a pump will perform in terms of head and flow.
To select a proper pump for a particular application it is necessary to utilize the system curve and the pump performance curve. The test rig required numerous different sets of orifice plates. This is the point where the system head curve crosses the pumps head vs. Head versus capacity power versus capacity npsh versus capacity. Detailed performance of a radialbladed centrifugal pump impeller in water by max j. Understanding pump performance curves progressive dairy. For example, in the pump performance chart shown below, pump efficiency declines from about 75% at full speed to about 55% at half speed while following the system curve with zero static head. Head the point on the system curve that intersects the pump curve is known as the operating point. The efficiency of centrifugal pumps varies over the individual curve. Attempts to predict the performance characteristics of centrifugal pumps designed to handle clear. The corresponding values of the flow capacity and head are plotted on the main curve on the graph at various impeller sizes.
In our example below, these curves show the performance at 1450 rpm for a 3 inlet2 outlet. Centrifugal pump performance curves part 1 youtube. Performance curves for different pumps can only be compared if they are stated with the same speed. Where these curves cross is the operating point see figure 3. Unlike positive displacement pumps such as piston pumps, centrifugal pumps deliver a var iable flow rate q increasing. Operating line system curve this is dependent on the system you are putting the pump into. This tech brief examines how pump curves can provide data about a pumps abili ty to produce flow against. 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. Figure 44 shows only the information relevant to the 8 12 impeller performance curve.
The system curve is a graphical representation of the relationship between discharge and head loss in a system of pipes the system curve is completely independent of the pump characteristics the basic shape of the system cur. Care must be taken to correctly read the performance data from pump curves. Flow, head, impeller trim diameter, efficiency, power, npshr, mcsf minimum continuous stable flow and rpm. The curve immediately above this point will be most suitable. In centrifugal pumps, the fluid enters along the centerline of the pump, is pushed outward by the rotation of the impeller blades, and exits along the outside of the pump. The curves can be converted to the same speed by the formulas of affinity laws, which will also be explained later. The pump flow capacity, shown on the xaxis of the pump performance curve, represents the gallons per minute gpm that the pump will pump at any given point during its operation. California state polytechnic university, pomona mechanical engineering department memorandum to. A step by step guide example as an example, size a pump to pump 50 gallons per minute and generate 5 feet of head. A typical composite curve includes the pump performance curves, horsepower curves and npsh required. Point a o on the performance curve is where the desired flow rate gpm and total dynamic head tdh points intersect.
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. The head and flow rate determine the performance of a pump, which is graphically shown in the. Motor and pump performance curve winner hydraulics. Taco comfort solutions understanding pump curves td09. Selecting a positive displacement pump using performance. Pumps can generate high volume flow rates when pumping against lowpressure head or low volume flow rates when pumping against highpressure head. A pump performance curve indicates how a pump will perform in regards to pressure head and flow. How to read a centrifugal pump curve crane engineering. The pump curve directly above the duty point is the 722. This is an overview of pump capabilities as detailed on the pumps performance curve.
Below you will find performance curve information for the vaughan horizontal, vertical, pedestal and submersible pumps. Manufacturers will put several different trim curves on a pump performance curve to make pump specification easier, although this sometimes makes the pump performance curve more difficult to read. Selecting a positive displacement pump using performance curves. Qh curves will be given by the manufacturer of the pump and can normally be considered as a simple quadratic curve. The engineer receives a pump performance curve from the sales representative as part of the pump purchase. A pump will operate where its performance curve intersects the system resistance curve above centre as shown by the dotted lines. Aug 21, 2011 what is a centrifugal pump performance curve, how do you read and use it. In general, pump curves are designed according to iso 9906 annex a, which specifies the tolerances of the curves. The h in the curve is the difference in energy level between the suction and the pressure side of the pump. Different pumps that operate with different pump curves will all operate along the system curves but at different fixed points. 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. Now consider a centrifugal pump is required to pump water from one vessel to another vessel, the pump parameters. If the duty point is not exactly on the pump curve, the performance of the pump can be adjusted by throttling the flow, reducing the impeller diameter or adjusting the output speed of the drive. Teikoku canned motor pumps playing a role in various situations around the globe teikoku electric, the worlds leading canned motor pump manufacturer pump performance curvetechnical informationproduct linesteikoku electric mfg.
In the composite shown bottom of the graph and 5 feet on the side. Understanding how to read a positive displacement pump curve can help troubleshoot a currently installed system, or help to size equipment for the next project down the road. Dec 07, 2014 fluid mechanics centrifugal pump performance experiment 1. Reading centrifugal pump curves national environmental. It is made up of four to five points, each point being obtained from a separate npsh test at a different constant flow. This is an overview of pump capabilities as detailed on the pump s performance curve. For any of the flii pumps, use the curve on page 32 and for the fkl pump use the curve on page 11. Fluid mechanics centrifugal pump performance experiment. Sep 26, 2015 centrifugal pumps performance curve 14. At each pump curve intersection, the flow and tdh is fixed.
Fluid mechanics centrifugal pump performance experiment 1. The characteristic curves of centrifugal pumps plot the course of the following parameters against flow rate q. Soltis lewis research center summary shrouded and unshrouded versions of a 7. It is good practice to select a pump with an impeller.
A curve is defined for a specific operating speed rpm and a specific inletoutlet diameter. What is a centrifugal pump performance curve, how do you read and use it. The curves for power consumption and efficiency will normally only cover the pump part of the unit i. Numerous graphs and corrective factors are needed to produce the pump curve. Analysis the data plotted should show an increase in flow rate with decreasing elevation like a typical pump performance curve. How to read a centrifugal pump performance curve mechanical. Positive displacement pumps can handle many difficult applications. On one axis of the pump curve, you will find capacity, and on the other, total dynamic head tdh. This curve is plotted on the pump manufacturers performance curve for a given pump and it shows the relationship between the head and capacity flow rate of a given pumpimpeller combination. The characteristic curves shape is primarily determined by the pump type i.
Pump performance curves generally show performance for various impeller diameters or trims. What is the importance of performance curve of pumps in. Centrifugal pump curves show 8 important factors that are critical in selecting the right pump for your application. Knowing how to read a centrifugal pump curve is essential to the health of your system. Jul 07, 2014 analysis the data plotted should show an increase in flow rate with decreasing elevation like a typical pump performance curve. The pump curve also displays the pump model, the pump size and number of stages for multistage pumps. The performance overlap region, where both pump types should be considered, is presented with guidelines to evaluate proper. This is normally carried out after the abovementioned tests. In this study, different techniques for improving centrifugal pump performance by changing impeller geometry are discussed. To find the operating point at which a particular piping system and circulator will settle, you can plot a system head loss curve for the piping system on the same graph as the pump curve. Running too far out on the curve, or too far back, can cause damage to the pump, excessive energy consumption, and overall poor performance. Draw a sketch of the pump bucket tube system with a control volume around the whole system. However, the data needs to be corrected to account for head loss in the tubing. The centrifugal pump characteristic curves show the law and.
Motor and pump performance curve s3 ratting percentage of 10 minute cycle nominal duty curve s2 ratting time to reach 150 brush temperature. The pump characteristic curves are compared with utility defined system curve so that the pump having maximum efficiency in the working region may be identified. 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. Locate the calculated differential pressure on the vertical axis 1. That is, analyze the system to determine the pump head required as a function of flow rate through the pump this will form the system line.
Prediction of headcapacity curve agrees reasonably well with the experimental results over the full range of operating conditions. Vaughan pump performance curves resources to assist you. In the curve below for a rotary lobe pump, multiple viscosities are shown to determine the pump horsepower. To change the operating point either the system curve or the pump curve must be changed. For other pumps, the magnitude of the decrease in pump efficiency may be negligible. Pump performance curvetechnical informationproduct lines. May 03, 2018 it is made up of four to five points, each point being obtained from a separate npsh test at a different constant flow. Pdf centrifugal pump performance characteristics for domestic. Centrifugal pump performance drop due to leading edge cavitation view the table of contents for this issue, or go to the journal homepage for more 2012 iop conf. As an example in the above curve, consider an ndp40 series pump performance curve with rubber diaphragms, pumping 80 gpm at 50ft tdh. This improvement can be achieved by making geometrical changes in design of an impeller. Pump performance, splitter blades, diffuser, tip clearance 1.
These pdf s contain detailed information, but please consult vaughan or your vaughan representative to assist with your final pump selection. Prediction of performance characteristics of a centrifugal. Jordan, an application engineer at crane engineering, explains how to read a centrifugal pump curve in the video below. To do that, an engineer would refer to a pumps composite curve. It merely reiterates the head and flow values estimated in steps 1 and 2 by. The flow rate q and the developed head h are both determined by the intersection. This basic difference is evident in the pumps response to a systems headflow curve. Several pump applications are presented to illustrate the selection process needed to insure pump reliability. Single and three phase 3600 rpm and 1800 rpm electric motors.
Gallons per minutes total head feet 5 10 15 20 npshr feet 2000 rpm 1800 rpm 1600 rpm 1400 rpm 50 60 70 30 hp 40 hp 50 hp 60 hp 75 hp 80 83 80 150 hp 125 hp 100 hp npshr 1760 rpm 0 250 500 750 1250 1500 1750 2000 2250 2500 2750 0 40 80 120 160 200 240 280. Centrifugal pump performance curves and technical information. 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. What is the importance of performance curve of pumps in industry. Centrifugal pump characteristic curve components of. This point determines compressed air requirements for the particular pump. Therefore the constant between each curve is the capacity or xaxis. The head at this point corresponds to the shutoff head of the pump, point a in figure 4.
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