Unit 571 new smyrna beach, fl 32128 386882ezce3923. Below diagram demonstrate that at a flow rate of 100 lpm or 6 m 3 h, the pump will produce 3. Pdf laboratory report centrifugal pump anh phuong le. The h tq curve shows the relationship between head and flow rate. Information is plotted on an xy graph where the xaxis is measured in units of flow and the yaxis is measured in units of head, power, and npshr.
When reading pump curves, simply type in your duty point or just click directly on the graph and compare it to the pump curve. Examples of such parameters are the impeller diameter see impeller trimming, preswirl control see figs. 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. This type of curve is referred to as a rising characteristic curve. How it operates in practice is determined by the resistance of the system it is installed in. Pump selection, sizing and interpretation of performance curves 4 3 performance curve at some point in the pump selection process, the impeller diameter is selected. 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. Typically a pump performance curve will carry information about the following points. A typical composite curve includes the pump performance curves, horsepower curves and npsh required.
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. A graphical representation of these factors is called. Efficiency considerations e during the pump selection process, only pumps pump b having high efficiencies above 70% for the design pump a discharge should be considered for a system. Characteristic curves for a singlestage centrifugal and other components. Centrifugal pump characteristic curve engineers edge. Combined curve for pumps a and 8 shows a headdischarge characteristic curve for two operating in series pumps operating in parallel. 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. Learn about pump characteristic curve in this excerpt from the pumps and motors lecture from our distribution exam prep course. Centrifugal pump performance curves and technical information. The efficiency of centrifugal pumps varies over the individual curve. The pump performance curve describes the relation between the flowrate and the head for the actual pump. Positive displacement pumps have a constant torque characteristic, whereas centrifugal pumps demonstrate variable torque characteristics.
In a piping system, pressure loss due to friction increases with increasing fluid flow. This set of four curves is known as the pump characteristic curves or pump performance curves. However, the curve does exist and if you insist you can probably get it. After a pump is installed in a system, it is usually tested to ensure that the flow rate and head of the pump are within the required specifications. The pump application may limit the access of personnel for a thorough. Operating characteristic curves of a centrifugal pump. Other important information for a proper pump selection is also included like efficiency curves, npsh r curve, pump curves for. A pump performance curve indicates how a pump will perform in regards to pressure head and flow. A pump curve provides a wealth of information regarding the performance capabilities of a pump.
Suitable for application pump speeds up toapi674 1995andhydraulicinstitutespeedlimitations. A centrifugal pump performance curve is a tool that shows how a pump will perform in terms of head and flow. Theory one way of illustrating pump characteristics is to construct contour lines of. How to read a centrifugal pump curve crane engineering. Each of the characteristics is explained in the next sections for propeller pumps. Whats the significance of pump characteristic curves. Use either of the following equations to determine the new ed or use equations involving d to determine the trim pump characteristic curve 4. Qh curves will be given by the manufac turer of the. Understanding centrifugal pump curves when selecting a centrifugal pump, one should match the performance of the pump to that needed by the system. Aug 22, 2017 learn about pump characteristic curve in this excerpt from the pumps and motors lecture from our distribution exam prep course. The characteristic curves shape is primarily determined by the pump type i. Characteristic curves for a centrifugal pump examining figure 3, the general performance of the pump can be determined. Centrifugal pump characteristic curve components of. 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.
Sep 24, 2018 centrifugal pump curves show 8 important factors that are critical in selecting the right pump for your application. 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 monitoring and determination of pump. What follows is a brief presentation of the different pump performance curves. Manufacturers data for this pump is contained in figures 7.
The pump performance curves are based on data generated in a test rig. The single most energy efficient discharge versus head point on the pump curve is termed as the best efficiency point bep. Components of centrifugal pump performance curve 1. The pump characteristic is normally described graphically by the manufacturer as the pump performance curve. On the left side of the curve, minimum flow is indicated by a vertical bold line. 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.
Reading centrifugal pump curves national environmental. The characteristic curves of centrifugal pumps plot the course of the following parameters against flow rate q. For the choice of the right pump, the system characteristic curve or data must be known about it. The curve immediately above this point will be most suitable. Pump headflow curves are typically given for clear water. Pump characteristic an overview sciencedirect topics. To do that, an engineer would refer to a pumps composite curve. To change the operating point either the system curve or the pump curve must be changed. The pump curve directly above the duty point is the 722. In some cases an additional pressure behind the impellers to the point that the. In short, pump curve show you how a pump perform at any given point of its range. The flow rate q and the developed head h are both determined by the intersection. Flow, head, impeller trim diameter, efficiency, power, npshr, mcsf minimum continuous stable flow and rpm. The curves for power consumption and efficiency will normally only cover the pump part of the unit i.
The pump curve describes how a centrifugal pump performs in isolation from plant equipment. The headdischarge curve hq curve relates the head produced by a pump to the volume of water pumped per unit time i. A centrifugal pump requires a minimum amount flow to be moving through the pump to dissipate heat created. A vendor manual for a specific pump usually contains a curve of pump flow rate versus pump head called a pump characteristic curve. You can also do quick calculations on efficiency, speed and p1. For an existing pump, the diameter of the impeller is known. This is the primary information reported in the pump performance curves and very important information regarding most of the pump calculations related to differential pressure across the pump. Certrifugal pump reciprocating pump schematic diagram characteristic curve is essential.
Pump cavitation is caused by the reduction in system heads. A curve is defined for a specific operating speed rpm and. The starting point for the curve at no flow, will be the same. Qh curves will be given by the manufacturer of the pump and can normally be considered as a simple quadratic curve. Pdf laboratory report centrifugal pump anh phuong le vu. 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. 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. The operating point adapts itself to the intersection point of these two lines in dependence of pump characteristic curve and system characteristic curve automatically see diagram 5 24. For the sake of example, today were going to look at a selection made for the following design. The amount of pressure the pump is required to overcome dictates where the performance point will be on the curve and how much flow is produced. In this post, well break down the anatomy of a centrifugal pump curve.
Centrifugal pump characteristic curve components of centrifugal. 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. 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. Lower efficiency curves at other discharges and head, at the same speed and the same size impeller, when plotted.
The figure below shows the pump curve of a single pump a, two pumps operat ing in parallel b, and the system curve c. 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. Lesson 28 characteristic curves of centrifugal pumps. In fact, the curve reaches a high point prior to zero flow, then declines as it approaches shutoff. Centrifugal pump curves show 8 important factors that are critical in selecting the right pump for your application. The pump curve also displays the pump model, the pump size and number of stages for multistage pumps. The choice of pump for a given application depends largely on how the pump headflow characteristics match the requirement of the system downstream of the pump. Reading and understanding centrifugal pump curves is key to proper pump selection, and to their reliable and efficient operation. A centrifugal pump converts driver energy to kinetic energy in a liquid by accelerating the fluid to the outer rim of an impeller. Pdf dimensionless characteristics of centrifugal pump. Figure 4 shows a typical head, h ft, versus capacity discharge, q gpm, curve for a singlestage. 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.
Reading centrifugal pump curves environmental finance center. Cutoff point as qh curve reaches maximum discharge, when delivery valve is fully opened the flow velocity in the suction pipe may become so high that qh curve will drop abruptly in the vertical downward direction, the point where this drop occurs is known as cutoff point. In general, pump curves are designed according to iso 9906 annex a, which specifies the tolerances of the curves. Pumps operating in series pumps operating in parallel.
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. Well use sabre bav series pump curve as an example. The development in materials and pump construction have led to an increased life time and better reliability of the products. Pump manufacturers use the terminology called head and pump users use pressure to measure the performance. Not all manufacturers will provide you with the pump characteristic curve. Theoretical study and measurement of the characteristic. Centrifugal pump selection michael smith engineers.
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