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Experiment #10: Pumps
1. introduction.
In waterworks and wastewater systems, pumps are commonly installed at the source to raise the water level and at intermediate points to boost the water pressure. The components and design of a pumping station are vital to its effectiveness. Centrifugal pumps are most often used in water and wastewater systems, making it important to learn how they work and how to design them. Centrifugal pumps have several advantages over other types of pumps, including:
- Simplicity of construction – no valves, no piston rings, etc.;
- High efficiency;
- Ability to operate against a variable head;
- Suitable for being driven from high-speed prime movers such as turbines, electric motors, internal combustion engines etc.; and
A centrifugal pump consists of a rotating shaft that is connected to an impeller, which is usually comprised of curved blades. The impeller rotates within its casing and sucks the fluid through the eye of the casing (point 1 in Figure 10.1). The fluid’s kinetic energy increases due to the energy added by the impeller and enters the discharge end of the casing that has an expanding area (point 2 in Figure 10.1). The pressure within the fluid increases accordingly.
The performance of a centrifugal pump is presented as characteristic curves in Figure 10.2, and is comprised of the following:
- Pumping head versus discharge,
- Brake horsepower (input power) versus discharge, and
The characteristic curves of commercial pumps are provided by manufacturers. Otherwise, a pump should be tested in the laboratory, under various discharge and head conditions, to produce such curves. If a single pump is incapable of delivering the design flow rate and pressure, additional pumps, in series or parallel with the original pump, can be considered. The characteristic curves of pumps in series or parallel should be constructed since this information helps engineers select the types of pumps needed and how they should be configured.
2. Practical Application
Many pumps are in use around the world to handle liquids, gases, or liquid-solid mixtures. There are pumps in cars, swimming pools, boats, water treatment facilities, water wells, etc. Centrifugal pumps are commonly used in water, sewage, petroleum, and petrochemical pumping. It is important to select the pump that will best serve the project’s needs.
3. Objective
The objective of this experiment is to determine the operational characteristics of two centrifugal pumps when they are configured as a single pump, two pumps in series, and two pumps in parallel.
Each configuration (single pump, two pumps in series, and two pumps in parallel) will be tested at pump speeds of 60, 70, and 80 rev/sec. For each speed, the bench regulating valve will be set to fully closed, 25%, 50%, 75%, and 100% open. Timed water collections will be performed to determine flow rates for each test, and the head, hydraulic power, and overall efficiency ratings will be obtained.
5. Equipment
The following equipment is required to perform the pumps experiment:
- P6100 hydraulics bench, and
6. Equipment Description
The hydraulics bench is fitted with a single centrifugal pump that is driven by a single-phase A.C. motor and controlled by a speed control unit. An auxiliary pump and the speed control unit are supplied to enhance the output of the bench so that experiments can be conducted with the pumps connected either in series or in parallel. Pressure gauges are installed at the inlet and outlet of the pumps to measure the pressure head before and after each pump. A watt-meter unit is used to measure the pumps’ input electrical power [10].
7.1. General Pump Theory
Consider the pump shown in Figure 10.3. The work done by the pump, per unit mass of fluid, will result in increases in the pressure head, velocity head, and potential head of the fluid between points 1 and 2. Therefore:
- work done by pump per unit mass = W/M
P : pressure
v : flow velocity
g : acceleration due to gravity
z : elevation
Applying Bernoulli’s equation between points 1 and 2 in Figure 10.3 results in:
Since the difference between elevations and velocities at points 1 and 2 are negligible, the equation becomes:
Dividing both sides of this equation by gives:
The right side of this equation is the manometric pressure head, H m , therefore:
7.2. Power and Efficiency
The hydraulic power ( W h ) supplied to the fluid by the pump is the product of the pressure increase and the flow rate:
The pressure increase produced by the pump can be expressed in terms of the manometric head,
7.3. Single Pump – Pipe System performance
While pumping fluid, the pump has to overcome the pressure loss that is caused by friction in any valves, pipes, and fittings in the pipe system. This frictional head loss is approximately proportional to the square of the flow rate. The total system head that the pump has to overcome is the sum of the total static head and the frictional head. The total static head is the sum of the static suction lift and the static discharge head, which is equal to the difference between the water levels of the discharge and the source tank (Figure 10.4). A plot of the total head-discharge for a pipe system is called a system curve ; it is superimposed onto a pump characteristic curve in Figure 10.5. The operating point for the pump-pipe system combination occurs where the two graphs intercept [10].
7.4. Pumps in Series
Pumps are used in series in a system where substantial head changes take place without any appreciable difference in discharge. When two or more pumps are configured in series, the flow rate throughout the pumps remains the same; however, each pump contributes to the increase in the head so that the overall head is equal to the sum of the contributions of each pump [10]. For n pumps in series:
The composite characteristic curve of pumps in series can be prepared by adding the ordinates (heads) of all of the pumps for the same values of discharge. The intersection point of the composite head characteristic curve and the system curve provides the operating conditions (performance point) of the pumps (Figure 10.6).
7.5. Pumps in Parallel
Parallel pumps are useful for systems with considerable discharge variations and with no appreciable head change. In parallel, each pump has the same head. However, each pump contributes to the discharge so that the total discharge is equal to the sum of the contributions of each pump [10]. Thus for pumps:
The composite head characteristic curve is obtained by summing up the discharge of all pumps for the same values of head. A typical pipe system curve and performance point of the pumps are shown in Figure 10.7.
8. Experimental Procedure
8.1. Experiment 1: Characteristics of a Single Pump
a) Set up the hydraulics bench valves, as shown in Figure 10.8, to perform the single pump test.
b) Start pump 1, and increase the speed until the pump is operating at 60 rev/sec.
c) Turn the bench regulating valve to the fully closed position.
d) Record the pump 1 inlet pressure (P 1 ) and outlet pressure (P 2 ). Record the input power from the watt-meter (Wi). (With the regulating valve fully closed, discharge will be zero.)
e) Repeat steps (c) and (d) by setting the bench regulating valve to 25%, 50%, 75%, and 100% open.
f) For each control valve position, measure the flow rate by either collecting a suitable volume of water (a minimum of 10 liters) in the measuring tank, or by using the rotameter.
g) Increase the speed until the pump is operating at 70 rev/sec and 80 rev/sec, and repeat steps (c) to (f) for each speed.
8.2. Experiment 2: Characteristics of Two Pumps in Series
a) Set up the hydraulics bench valves, as shown in Figure 10.9, to perform the two pumps in series test.
b) Start pumps 1 and 2, and increase the speed until the pumps are operating at 60 rev/sec.
d) Record the pump 1 and 2 inlet pressure (P 1 ) and outlet pressure (P 2 ). Record the input power for pump 1 from the wattmeter (Wi). (With the regulating valve fully closed, discharge will be zero.)
Note: Wattmeter readings should be recorded for both pumps, assuming that both pumps have the same input power.
8.3. Experiment 3: Characteristics of Two Pumps in Parallel
a) Configure the hydraulic bench, as shown in Figure 10.10, to conduct the test for pumps in parallel.
b) Repeat steps (b) to (g) in Experiment 2.
9. Results and Calculations
Please visit this link for accessing excel workbook of this manual.
9.1. Result
Record your measurements for Experiments 1 to 3 in the Raw Data Tables.
Raw Data Table
(bar) | |||||
(bar) | |||||
(bar) | |||||
(bar) | |||||
(bar) | |||||
(bar) | |||||
9.2. Calculations
- If the volumetric measuring tank was used, then calculate the flow rate from:
- Correct the pressure rise measurement (outlet pressure) across the pump by adding a 0.07 bar to allow for the difference of 0.714 m in height between the measurement point for the pump outlet pressure and the actual pump outlet connection.
- Convert the pressure readings from bar to N/m 2 (1 Bar=10 5 N/m 2 ), then calculate the manometric head from:
- Calculate the overall efficiency from Equation 7.
– Overall head for pumps in series is calculated using Equation 8b. – Overall head for pumps in parallel is calculated using Equation 9b. – Overall electrical input power for pumps in series and in parallel combination is equal to (Wi) pump1 +(Wi) pump2 .
- Summarize your calculations in the Results Tables.
Result Tables
/s) | |||||
(N/m ) | |||||
(N/m ) | |||||
(Watts) | |||||
(%) |
/s) | |||||
(N/m ) | |||||
(N/m ) | |||||
(%) |
Use the template provided to prepare your lab report for this experiment. Your report should include the following:
- Table(s) of raw data
- Table(s) of results
- Plot head in meters as y-axis against volumetric flow, in liters/min as x-axis.
- Plot hydraulic power in watts as y-axis against volumetric flow, in liters/min as x-axis.
- Plot efficiency in % as y-axis against volumetric flow, in liters/min as x-axis on your graphs.
In each of above graphs, show the results for single pump, two pumps in series, and two pumps in parallel – a total of three graphs. Do not connect the experimental data points, and use best fit to plot the graphs
- Discuss your observations and any sources of error in preparation of pump characteristics.
Applied Fluid Mechanics Lab Manual Copyright © 2019 by Habib Ahmari and Shah Md Imran Kabir is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.
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Experiments on Performance of Gear Pump
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These gear pumps can work on high differential pressures in a way that the outlet side pressure is higher than the inlet pressure. However, there are certain clearances which allow the movement of the dynamic seal parts, and it also permits fluid to slip back and reduce its efficiency. The main components of the gear pump are the casing, gear wheel, and the suction and delivery pipe. 2 Casing makes contact between the liquid to be transferred and the gear wheel . The intermeshing of two identical gears takes place in gear wheel pump in which one of them is connected to the driving shaft while the other one revolves due to the driving shaft. The suction pipes are circular shaped which connects the gear to suction and delivery.
REQUIREMENTS
Materials: Gear Oil Pump Test Rig
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COMMENTS
In this lab experiment, we solved for the various characteristic of a gear pump. The values of the pump speed, flow rate, suction and discharge pressure were taken by running the setup. Using these already measured quantities, other properties such as pump head , hydraulic power, efficiency and the net positive suction head is measured. Table ...
The gear pump you will test in this experiment is an external gear type. The pump consists of two spur gears inside an enclosure and in mesh with each other, as shown in the figure below. Figure 2 Gear pump. The liquid is carried in the pockets formed between the gear teeth and the housing as the two gears rotate.
a) Set up the hydraulics bench valves, as shown in Figure 10.8, to perform the single pump test. b) Start pump 1, and increase the speed until the pump is operating at 60 rev/sec. c) Turn the bench regulating valve to the fully closed position. d) Record the pump 1 inlet pressure (P 1) and outlet pressure (P 2 ).
(Year 1 Lab Report Booklet 2019/2020) Figure 4: Static head Hs against flow rate- 50% pump speed Figure 5: pump characteristics against flow rate- cavitation Comparing the figures 2,3 and 5 it can be observed that all graphs have a similar shape ( a negative correlation). ... For gear pump experiment, figure 6 clearly shows the relation between ...
First of all, fill about 75 % of the reservoir tank capacity with any of standard oil, such as SAE 40. Now, with the partial opening of the delivery pump, start the pump set. After this, adjust the head of the pump with the help of delivery valve. Now, record the time taken while collecting ten c.c of oil, and also note down the readings of ...
Structures/Motion Lab (1998-1999) 20-263-571, Sections 001, 002, 003 CENTRIFUGAL PUMP TEST LAB OBJECTIVE: The objective of this exper iment is to determine the perfor mance character istics of a centr ifugal pump. This is accomplished by deter mining the capacity and efficiency of a centr ifugal pump when operating under the assigned conditions.
This document contains the results of Experiment 4: Gear Pump Performance Test. It includes data tables showing measurements of suction and delivery pressure, volume flow rate, electric and hydraulic power, and efficiency at two different pump speeds. Plots of hydraulic power vs efficiency for each speed are also presented. Sections for sample computations, findings/analysis, conclusion, and ...
A continuous pump flow rig is used in this lab experiment, as sketched in Figure 4. It is basically the same rig as the one that is used in the pipe flow experiment except that the pipe specimens are replaced by a centrifugal test pump, connected by flexible hoses.
This document provides information about Experiment 4 which tests the performance of a gear pump. The experiment aims to identify characteristic data and investigate dependencies of the gear pump with respect to the effect of pressure limitation. It addresses program outcomes related to conducting experiments and applying engineering knowledge to solve problems. The document also outlines ...
Exeriment-4 - Free download as Word Doc (.doc / .docx), PDF File (.pdf), Text File (.txt) or read online for free. This lab report details an experiment that measured the pressure, flow rate, power and efficiency of a gear pump at 250 rpm and 500 rpm. Performance data. This lab report details an experiment that measured the pressure, flow rate ...
Fundamentals of External Gear Pump Design . L. OGAN . T. W. ILLIAMS. ... U. S. Naval Research Laboratory 4555 Overlook Avenue SW Washingto n, DC 20375-5320. 8. PERFORMING ORGANIZATION ... point for a gear pump design. The scope of this report includes the quantitative and qualitative parameters and metrics to define pump performance, design of ...
Experiment: Performance Test on Gear PumpPresented and explained by: Mr. Jipson MathewCamera: Mr. Tom Thomas, Mr. K. N. Somanathan AsariEditing: Prof. Jose T...
dosing pump to supply a specified amount of chemical per pump revolution is critical. Chemical plants equally require pumps that can deliver a fixed volume of fluid per unit revolution. Gear pumps belong to the group of positive displacement pumps which are characterized with fixed volume discharge per unit revolution of the pump.
PDF | On Jun 1, 2017, M. E. Qazizada and others published Comparison of Gear and Peripheral pumps performance, evaluation of their reliability at operation region | Find, read and cite all the ...
ME 142L Gear Pump Test Experimentmade - Free download as Word Doc (.doc / .docx), PDF File (.pdf), Text File (.txt) or read online for free. The document describes an experiment to analyze the performance characteristics of a gear pump. The objectives are to familiarize students with operating a gear pump, measure its efficiency, and observe the relationships between flow rate, head pressure ...
The document describes a lab experiment on a gear pump. The objective is to identify the pump's characteristic data and investigate dependencies. The apparatus includes a gear pump setup with sensors for pressure, temperature, and flow rate. Procedures are described to collect data by varying the pump speed and throttling valve position, and plotting graphs of flow rate and pressure versus ...
Small external gear pumps usually operate at 1750 or 3450 rpm and larger models operate at speeds up to 640 rpm. External gear pumps have close tolerances and shaft support on both sides of the gears. This allows them to run to pressures beyond 3,000 PSI / 200 BAR, making them well suited for use in hydraulics.