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. Single and three phase 3600 rpm and 1800 rpm electric motors. In our example below, these curves show the performance at 1450 rpm for a 3 inlet2 outlet. Point a o on the performance curve is where the desired flow rate gpm and total dynamic head tdh points intersect. To change the operating point either the system curve or the pump curve must be changed. The head and flow rate determine the performance of a pump, which is graphically shown in the. The efficiency of centrifugal pumps varies over the individual curve. The pump curve also displays the pump model, the pump size and number of stages for multistage pumps.
This is normally carried out after the abovementioned tests. 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. The test rig required numerous different sets of orifice plates. Vaughan pump performance curves resources to assist you. 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. In the composite shown bottom of the graph and 5 feet on the side. The h in the curve is the difference in energy level between the suction and the pressure side of the pump. As an example in the above curve, consider an ndp40 series pump performance curve with rubber diaphragms, pumping 80 gpm at 50ft tdh. The engineer receives a pump performance curve from the sales representative as part of the pump purchase. Let us look again at examples of stable and unstable pump curves.
Several pump applications are presented to illustrate the selection process needed to insure pump reliability. In this study, different techniques for improving centrifugal pump performance by changing impeller geometry are discussed. 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. Flow, head, impeller trim diameter, efficiency, power, npshr, mcsf minimum continuous stable flow and rpm. It merely reiterates the head and flow values estimated in steps 1 and 2 by. Centrifugal pump pump curves pumps can generate high volume flow rates when pumping against low pressure. At each pump curve intersection, the flow and tdh is fixed. The flow rate q and the developed head h are both determined by the intersection. Motor and pump performance curve s3 ratting percentage of 10 minute cycle nominal duty curve s2 ratting time to reach 150 brush temperature. To select a proper pump for a particular application it is necessary to utilize the system curve and the pump performance curve.
Positive displacement pumps can handle many difficult applications. 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. Centrifugal pump performance curves part 1 youtube. Taco comfort solutions understanding pump curves td09. Now consider a centrifugal pump is required to pump water from one vessel to another vessel, the pump parameters. 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. Attempts to predict the performance characteristics of centrifugal pumps designed to handle clear. Reading centrifugal pump curves environmental finance center. Components of centrifugal pump performance curve 1.
For any of the flii pumps, use the curve on page 32 and for the fkl pump use the curve on page 11. Sep 26, 2015 centrifugal pumps performance curve 14. Pdf centrifugal pump performance characteristics for domestic. These pdf s contain detailed information, but please consult vaughan or your vaughan representative to assist with your final pump selection. Locate the calculated differential pressure on the vertical axis 1. A curve is defined for a specific operating speed rpm and a specific inletoutlet diameter. This is an overview of pump capabilities as detailed on the pumps performance curve. 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.
How to read a centrifugal pump curve crane engineering. Pump performance curvetechnical informationproduct lines. This basic difference is evident in the pumps response to a systems headflow curve. Performance curves for different pumps can only be compared if they are stated with the same speed. 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. Understanding centrifugal pump curves when selecting a centrifugal pump, one should match the performance of the pump to that needed by the system. Different pumps that operate with different pump curves will all operate along the system curves but at different fixed points. The head at this point corresponds to the shutoff head of the pump, point a in figure 4. This tells us what the pump is capable of flowing if we fulfill the other inputs. It isconcluded that the leakage lossplays a major role inthe performance of a centrifugal slurry pump. 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. Dec 07, 2014 fluid mechanics centrifugal pump performance experiment 1. What is a centrifugal pump performance curve, how do you read and use it.
California state polytechnic university, pomona mechanical engineering department memorandum to. The pump curve directly above the duty point is the 722. Care must be taken to correctly read the performance data from pump curves. Motor and pump performance curve winner hydraulics. In the curve below for a rotary lobe pump, multiple viscosities are shown to determine the pump horsepower. Detailed performance of a radialbladed centrifugal pump impeller in water by max j. The characteristic curves shape is primarily determined by the pump type i. 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. Head versus capacity power versus capacity npsh versus capacity. The performance overlap region, where both pump types should be considered, is presented with guidelines to evaluate proper. 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. Numerous graphs and corrective factors are needed to produce the pump curve. Pump performance curves generally show performance for various impeller diameters or trims.
Head the point on the system curve that intersects the pump curve is known as the operating point. This point determines compressed air requirements for the particular pump. Below you will find performance curve information for the vaughan horizontal, vertical, pedestal and submersible pumps. Jul 07, 2014 analysis the data plotted should show an increase in flow rate with decreasing elevation like a typical pump performance curve. This improvement can be achieved by making geometrical changes in design of an impeller. Unlike positive displacement pumps such as piston pumps, centrifugal pumps deliver a var iable flow rate q increasing. Centrifugal pump performance experiment the purpose of this experiment was to determine the performance. A curve is defined for a specific operating speed rpm and. Pdf water pressure problems at home can be quite frustrating in daily life. Actual on site performance will be given by the intersection of the pump curve with the actual system curve. This tech brief examines how pump curves can provide data about a pumps abili ty to produce flow against. Soltis lewis research center summary shrouded and unshrouded versions of a 7. What is the importance of performance curve of pumps in. Jordan, an application engineer at crane engineering, explains how to read a centrifugal pump curve in the video below.
In fluids dynamics the term pump head is used to measure the kinetic energy which a pump creates. A step by step guide example as an example, size a pump to pump 50 gallons per minute and generate 5 feet of head. 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. Centrifugal pump performance curves and technical information. Prediction of headcapacity curve agrees reasonably well with the experimental results over the full range of operating conditions. What follows is a brief presentation of the different pump performance curves. How to read a centrifugal pump performance curve mechanical. Where these curves cross is the operating point see figure 3. 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. 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. Therefore the constant between each curve is the capacity or xaxis. The centrifugal pump characteristic curves show the law and.
Pdf centrifugal pump performance drop due to leading. Figure 44 shows only the information relevant to the 8 12 impeller performance curve. Fluid mechanics centrifugal pump performance experiment 1. Reading centrifugal pump curves national environmental. Draw a sketch of the pump bucket tube system with a control volume around the whole system. 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. Operating line system curve this is dependent on the system you are putting the pump into. What is the importance of performance curve of pumps in industry. 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. 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. A pump performance curve indicates how a pump will perform in regards to pressure head and flow. For other pumps, the magnitude of the decrease in pump efficiency may be negligible. The corresponding values of the flow capacity and head are plotted on the main curve on the graph at various impeller sizes.
To determine the performance data at a particular point, first locate the operating point of the pump. Pump performance curve a centrifugal pump performance curve is a tool that shows how a pump will perform in terms of head and flow. The characteristic curves of centrifugal pumps plot the course of the following parameters against flow rate q. 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.
Follow the pressure line, down and to the right, until it intersects 3 the product viscosity 2. A typical composite curve includes the pump performance curves, horsepower curves and npsh required. Selecting a positive displacement pump using performance. It is good practice to select a pump with an impeller. To do that, an engineer would refer to a pumps composite curve. It is made up of four to five points, each point being obtained from a separate npsh test at a different constant flow. The curves can be converted to the same speed by the formulas of affinity laws, which will also be explained later. This is an overview of pump capabilities as detailed on the pump s performance curve.
Aug 21, 2011 what is a centrifugal pump performance curve, how do you read and use it. Understanding pump performance curves progressive dairy. Detailed performance of radialbladed centrifugal pump. The curves for power consumption and efficiency will normally only cover the pump part of the unit i.
In general, pump curves are designed according to iso 9906 annex a, which specifies the tolerances of the curves. Pumps can generate high volume flow rates when pumping against lowpressure head or low volume flow rates when pumping against highpressure head. This is the point where the system head curve crosses the pumps head vs. Knowing how to read a centrifugal pump curve is essential to the health of your system. 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. Analysis the data plotted should show an increase in flow rate with decreasing elevation like a typical pump performance curve. 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. However, the data needs to be corrected to account for head loss in the tubing.