Table of Contents
Abstract………………………………………………………………………………………2 Introduction…………………………………………………………………………………..3 Objective…………………………………………………………………………………….4 Theory……………………………………………………………………………………….5-8 Apparatus..…………………………………………………………………………………..9 Procedures……………………………………………………………………………………10-11 Results and calculation………………………………………………………………………12-16 Discussion……………………………………………………………………………………17 Conclusion...............................................................................................................................18 Recommendation…………………………………………………………………………….19 References…………………………………………………………………………………...20 Appendices..............................................................................................................................21
1
ABSTRACT
This experiment were conducted to investigate and demonstrate the operation and characteristics of the three different devices of flow meter. These three device has different accuracy of the data and also different in energy losses. The apparatus that we used in for Flow Meter Demonstration Unit experiment is the SOLTEQ Flow meter Measurement Apparatus (Model: FM 101).We have to identified three different types of flow meter contain that are found in the unit at the beginning of the experiment. Orifice meter, Venturi meter and a Rotameter were the flow meters that placed in this unit for this experiment. The Venturi and Orifice meter only can measured the output which not linear with the flow rate, Q. The volume that are used in this experiment is constant that is 3L. For the first part of this experiment we have to determine the flow rate by utilizing all three basic types of flow meter measurement. The flow rate of the venturi meter are calculate by using this equation
2 g ( h A −hC ) ¿
1 2
−1
At 2 2 ¿ ¿ ¿ and to calculate the orifice meter flow rate we have to used this equation A 1−¿ q=Cd x At x ¿
2 g ( hG−hH ) ¿
1 2
−1
At 2 2 ¿ ¿ ¿ . When the value of the rotameter increased the value for both venturi meter flow A 1−¿ q=Cd x At x ¿ rate and orifice meter flow rate are supposed to increase as well. For the second part for this experiment we have to investigate the loss coefficient of fluid through 90 degree elbow. For this part we have to calculate the velocity and also the velocity head of the fluid through 90 degree elbow. The value for both velocity and the velocity head calculated were both directly increasing when the flow rate are increased. For this part also we have to plot graph of differential of piezometer head against the velocity head and the graph that we should get is a straight line graph while the graph that we have been plotted were not a straight line graph. This is because there were some error occurs when we conducting the experiment.
2
INTRODUCTION
SOLTEQ Flowmeter Measurement Apparatus (Model: FM101) apparatus is designed to operate together with a basic hydraulic bench or any water supply. The apparatus is able to demonstrate the flow measurement comparison by using a venturi device, orifice device and rotameter . The flow comparison can be further be used to compare against the flow measurement of the hydraulics bench which can be either by Gravimeteric or Volumetric Method, depending on the type of hydraulics bench in use. Other features of the flow apparatus include a 90 degree elbow with pressure tappings before and after this elbow. The purpose of these features is to provide an added function to this apparatus to allow students to calculate the total head loss and loss coefficient when fluid flows through these devices. In short, the apparatus allows following range of experiment to be carried out: a) Direct comparison of flow measurement using venturi, orifice, rotameter and bench. b) Determination of total head loss and loss coefficient of fluid flow through a 90 degree elbow. c) Comparison of pressure drop against each device. In various industrial plants, the accuracy of the measurement is very important and an inaccurate measurement of the liquid flow can cause some serious problem in a industrial plants.
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OBJECTIVES The objective for this experiment is to determine the flow rate measurement by utilizing three basic types of flow measuring techniques that is rotameter, venturi meter and orifice meter. Other than that is to investigate the loss coefficient of fluid through 90 degree elbow.
4
THEORY There are three common apparatus to measures the flow rate in pipe or internal flow. The three common devices uses in this experiment is venturi meter, orifice meter and the rotameter. These three devices operates with the same principle which is the decrease in flow area in a pipe that will causes an increase in velocity and will cause the decreasing in pressure.
Rotameter The rotameter is a flow meter in which a rotating free float is the indicating element in this apparatus. Basically, the rotameter consists of a transparent tapered vertical tube through which fluid flow upward. Within the tube there are freely suspended “float” of pump-bob shape. The “float” of the pump-bob shape stop at the bottom end when there is no flow of fluid happen. As flow commences, the float rises until upward and buoyancy forces on it are balanced by its weight. The float rises only a short distance if the rate of flow is small, and vice versa. The points of equilibrium can be noted as a function of flow rate. With a well-calibrated marked glass tube, the level of the float becomes a direct measure of flow rate.
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Figure 1.1 Rotameter
Orifice meter The orifice meter is use as the metering device in a pipeline that consists of a concentric square-edged circular hole in a thin plate which is clamped between the flanges of the pipe. The pressure connection for attaching the separate pressure gauges are made at holes in the pipe walls on both side of the orifice plate. The downstream pressure tap is placed at the minimum pressure positions that assumed to be at the vena contracta. The centre of the inlet pressure tap is located between one-half and two pipe diameters from the upstream side of the orifice plate and usually a distance of one pipe diameter is employed. The equation of the venturi meter also can be applied for orifice meter
2 g (h7−h8)¿1 /2 −1 At 2 2 ¿ ¿ Actual,Q= 1− A Cd x At x ¿
( )
Where, 6
Cd = Coefficient of discharge (0.63) D7 = Orifice diameter = 16 mm D8 = Orifice upstream diameter = 26 mm At = Orifice area = 2.011 x 10-4 m2 A = Orifice upstream area = 5.309 x 10-4 m2 (h7 – h8) = Pressure difference across orifice (m)
Figure 1.2 Typical orifice meter Venturi meter This device consists of a venture tube and suitable differential pressure gauge. As we know the venture tube divide into 3 portion that is converging portion, a throat and a diverging portion.
2
3
Figure 1.3 Venturi meter
The first part is the converging portion and the function is to increase the velocity of the fluid and the lower its static pressure. A pressure difference between the inlet and the throat developed and the 7
pressure difference is then correlated with the rate of discharge. For the third part of venturi meter is the diverging cone that serves to change the area of the stream back to the entrance area and convert velocity head into pressure head. Assume incompressible flow and no frictional losses, from Bernoulli’s Equation
p1 v 1 p v + +Z 1= 2 + 2 + Z 2 ……………………………………………………………… (1) γ 2g γ 2g 2
2
Uses of the continuity Equation Q = A1V1 = A2V2 equation (1) becomes
A2 2 ¿ A1 1−¿ v p1 −p 2 + Z1 −Z 2= 2 ¿ γ 2g
………………………………………………………….. (2)
2
Ideal
2g(
p1− p 2 + Z1 −Z 2) ¿1 /2 γ A 2 2 −1 ¿¿2¿ ………………………………… (3) A1 1−¿ Q=A 2 V 2 =A 2 ¿
In the case of real fluid flow, the flow rate will be expected to be less than that given by equation (2). This is because of the frictional effects and the consequent head loss between inlet and throat. The non-ideal is accounted by insertion of an experimentally determined coefficient, Cd that is the coefficient of discharge. With Z1= Z2 in this apparatus, the equation (3) becomes
p1− p 2 1 /2 )¿ γ A 2 2 −12 ¿ ¿ ¿ ……………………………………. (4) A1 1−¿ Q=Cd x A 2 x ¿
2g( Actual
Where, Cd = Coefficient of discharge (0.98)
8
D2 = Throat diameter = 16 mm D1 = Inlet diameter = 26 mm At = Throat area = 2.011 x 10-4 m2 A = Inlet area = 5.309 x 10-4 m2 g = 9.81 m/s2 ρ = Density of water = 1000 kg/m3 P1 = Inlet pressure (Pa) P2 = Throat pressure (Pa)
90o elbow
When the upstream and downstream lines of linear friction gradient are extrapolated to the plane of fitting, a loss of piezometric head, ∆h, due to the fitting is found. By introducing the velocity heads to the upstream and downstream runs of pipe, total head loss, ∆H can be determined in which
∆ H=∆ h+
v1 v 2 − 2 g 2 g ………………………………………………………………….. (5) 2
2
The energy losses are proportional to the velocity head of the fluids as it is flows around the elbow and through an enlargement or contraction of the flow section, or through the valve. The terms of a dimensionless loss coefficient K are usually expressed the experimental values for the energy losses.
K=
∆H ∆H ∨ v 1 /2 g v 2 /2 g …………………………………………………………………. (6) 2
2
APPARATUS 9
4
5
6
1
2 7
8
Figure 1.4 SOLTEQ Flow meter Measurement Apparatus (Model: FM 101)
1. Discharge Valve 2. Water Outlet 3. Water Supply 4. Staddle Valve
5. Manometer 6. Rotameter 7. 90° elbow 8. orifice meter
Procedures
10
General start-up procedures The first thing that we do before we start the experiment was to fully close the flow control valve of hydraulic bench and fully open the discharge valve. The discharge has been ensure to properly directed to the volumetric tank of the fibreglass before we start the system. The flow discharge allowed back into the sump tank by ensure the volumetric tank valve is left open. The bench valve were slowly opened. At this point, the water flowing from the hydraulic bench to the flow apparatus and discharge through into the volumetric tank of hydraulic bench and then drained back into the sump tank of the hydraulic bench were observed. The procedure continued by fully opened the flow control valve. The bench valve were closed when the flow in the pipe was steady and there were no trapped bubble to reduce the flow to maximum measurable flow rate. The water level at the manometer board were begin to display different level of height. The level of the height for each tube of the manometer has been observed and the data were recorded in data sheet. At this point the flow were slowly reduce by controlling the flow discharge valve of the apparatus. The water level at the manometer board were began to level at straight level.
Demonstration of the operation and characteristic of three different basic type of flowmeter The apparatus were placed on the bench and the inlet pipe were connected to bench supply and the outlet pipe were into the volumetric tank. The pump supply from the hydraulic bench were start when the bench valve were fully closed and the discharge valve were fully opened. The bench valve were slowly opened until it is fully opened. The bench valve were closed when the flow in the pipe was steady and there were no trapped bubble to reduced the flow to the maximum measurable flow rate. The water level at the manometer board were adjusted by using the air bleed screw. The reading of the manometers with the maximum measurable flow rate were recorded in the data sheet. The reading of the rotameter were also recorded and the flow rate of the fluid were measured. The steps were repeated with different flow rates by adjusted the flow rates.
Determination of the loss coefficient when fluid flows through a 90 degree elbow The apparatus were placed on the bench and the inlet pipe were connected to bench supply and the outlet pipe were connected into the volumetric tank. The pump supply from the hydraulic bench were start when the bench valve were fully closed and the discharge valve were fully opened. The bench valve were slowly opened until it is fully opened. The bench valve were closed when the flow in the pipe was steady and there were no trapped bubble to reduced the flow to the maximum measurable flow rate. The water level at the manometer board were adjusted by using the air bleed screw. The 11
reading of the manometers with the maximum measurable flow rate were recorded in the data sheet. The reading of the rotameter were also recorded and the flow rate of the fluid were measured. The steps were repeated with different flow rates by adjusted the flow rates. A graph ΔH against VS2/2g for 90 degree elbow were plotted to determine the coefficient of losses.
Result and calculations
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Demonstration of the operation and the characteristic of three basic types of flowmeter B 239 259 291 333
C 229 221 209 210
Manometer reading (mm) D E F 235 237 238 242 248 255 265 276 286 290 309 325
No. 1 2 3 4
A 240 265 305 353
No.
Rotameter (l/min)
Vol (l)
Time (min)
Flowrate Q(l/min)
1 2 3 4
5 10 15 20
3 3 3 3
0.68 0.33 0.22 0.18
4.41 9.09 13.64 16.67
G 238 254 285 325
H 212 166 99 15
I 220 199 170 135
J 220 198 169 130
Flowrate using Bernoulli eq Venture(l/mi Orifice(l/min) n) 5.934 5.867 13.752 10.800 9.312 15.690 21.402 20.256
Calculation: Venturi flow rate Reading 1 1
2 g ( h A −hC ) ¿ 2 −1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1
2 ( 9.81 )( 0.24−0.229 ) ¿ 2 m3 /s ( 2.011 x 1 0−4 ) 2 −12 ¿¿ ¿ ( 5.309 x 1 0−4 ) 1−¿ −4 q=0.98 x (2.011 x 10 ) x ¿ 1.9708 x 1 0−4 x ¿ m 3 /s q=¿
3
q = 9.89x10-5 m /s
x
1000 1 min 60
q = 5.934 l/min
Reading 2
13
1
2 g ( h A −hC ) ¿ 2 −1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1 2
2 ( 9.81 )( 0.265−0.221 ) ¿ m3 /s ( 2.011 x 1 0−4 ) 2 −12 ¿ ¿ ¿ ( 5.309 x 10−4 ) 1−¿ −4 q=0.98 x (2.011 x 1 0 ) x ¿ 1.9708 x 1 0−4 x ¿ m 3 /s q=¿
3
q = 2.292x10-4 m /s
1000 1 min 60
x
q = 13.752 l/min Reading 3
2 g ( h A −hC ) ¿
1 2
−1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1
2 ( 9.81 )( 0.305−0.209 ) ¿ 2 m3 / s ( 2.011 x 1 0−4 ) 2 −12 ¿ ¿ ¿ ( 5.309 x 10−4 ) 1−¿ q=0.98 x (2.011 x 1 0−4) x ¿ 1.9708 x 1 0−4 x ¿ m 3 /s q=¿
q = 1.552x10
-4
3
m /s x
1000 1 min 60
q = 9.312 l/min 14
Reading 4 1
2 g ( h A −hC ) ¿ 2 −1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1 2
2 ( 9.81 )( 0.353−0.210 ) ¿ m3 / s ( 2.011 x 1 0−4 ) 2 −12 ¿ ¿ ¿ ( 5.309 x 10−4 ) 1−¿ −4 q=0.98 x (2.011 x 1 0 ) x ¿ 1.9708 x 1 0−4 x ¿ m 3 /s q=¿
3
q = 3.567x10-4 m /s
1000 1 min 60
x
q = 21.402 l/min
Orifice flowrate Reading 1
2 g ( hG−hH ) ¿
1 2
−1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1
2 ( 9.81 )( 0.238−0.212 ) ¿ 2 m3 /s ( 2.011 x 1 0−4 ) 2 −12 ¿ ¿ ¿ ( 5.309 x 10−4 ) 1−¿ q=0.63 x (2.011 x 1 0−4) x ¿
15
3
−4
1.267 x 1 0 x ¿ m /s q=¿
3
q = 9.778x10-5 m /s
1000 1 min 60
x
q = 5.867 l/min
Reading 2 1
2 g ( hG−hH ) ¿ 2 −1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1 2
2 ( 9.81 )( 0.254−0.166 ) ¿ m3 /s ( 2.011 x 10−4 ) 2 −12 ¿¿ ¿ ( 5.309 x 1 0−4 ) 1−¿ −4 q=0.63 x(2.011 x 10 ) x ¿ 1.267 x 1 0−4 x ¿ m3 /s q=¿
3
q = 1.80x10-4 m /s
x
1000 1 min 60
q = 10.8 l/min
Reading 3
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1
2 g ( hG−hH ) ¿ 2 −1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1 2
2 ( 9.81 )( 0.285−0.099 ) ¿ m3 / s ( 2.011 x 1 0−4 ) 2 −12 ¿ ¿ ¿ ( 5.309 x 10−4 ) 1−¿ −4 q=0.63 x (2.011 x 1 0 ) x ¿ 1.267 x 1 0−4 x ¿ m 3 /s q=¿
3
q = 2.615x10-4 m /s
1000 1 min 60
x
q = 15.69 l/min
Reading 4 1
2 g ( hG−hH ) ¿ 2 −1
At 2 2 ¿ ¿ ¿ A 1−¿ q=Cd x At x ¿ 1 2
2 ( 9.81 )( 0.325−0.015 ) ¿ m3 / s ( 2.011 x 1 0−4 ) 2 −12 ¿ ¿ ¿ ( 5.309 x 10−4 ) 1−¿ q=0.63 x (2.011 x 1 0−4) x ¿ 1.267 x 1 0−4 x ¿ m 3 /s q=¿
3
q = 3.376x10-4 m /s
x
1000 1 min 60
17
q = 20.256 l/min
Determination of the loss coefficient when fluid flows through a 90 degree elbow
Volume(L)
Time (sec)
3 3 3 3
41.03 19.90 13.00 10.90
Flowrate, Q (L/min)
Differential Piezometer V Head, (mm) (m/s) ( elbow hi-hj)
4.41 9.09 13.64 16.67
0 1 1 5
0.14 0.29 0.43 0.52
2
v 2g (mm) 0.99898 4.29 9.42 14.00
Calculation Reading 1 Choose the min flow rate, Q = 4.41 l/min = 7.35 X 10-5 m3/s Velocity of flow in the pipe (Diameter = 26 mm) 26 x 1 0−3 ¿2 π x¿ 4 7.35 X 10−5 m3 /s V= ¿ V = 0.14 m/s 2 0.14 ¿ ¿ ¿ 2 V =¿ 2g = 0.00099898 m = 0.99898 mm
Reading 2 18
Choose the min flow rate, Q = 9.09 l/min = 1.515 X 10-4 m3/s Velocity of flow in the pipe (Diameter = 26 mm) 26 x 10−3 ¿2 π x¿ 4 1.515 X 10−4 m3 / s V= ¿ V = 0.29 m/s 2 0.29 ¿ ¿ ¿ 2 V =¿ 2g = 0.00429 m = 4.29 mm
Reading 3 Choose the min flow rate, Q = 13.64 l/min = 2.273 X 10-4 m3/s Velocity of flow in the pipe (Diameter = 26 mm) 26 x 10−3 ¿ 2 π x¿ 4 2.273 X 10−4 m3 / s V= ¿ V = 0.43 m/s 0.43 ¿2 ¿ ¿ 2 V =¿ 2g = 0.00942 m = 9.42mm Reading 4 Choose the min flow rate, Q = 16.67 l/min = 2.778 X 10-4 m3/s Velocity of flow in the pipe (Diameter = 26 mm)
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−3 2
26 x 1 0 ¿ π x¿ 4 2.778 X 10−4 m3 /s V= ¿ V = 0.52 m/s 2
0.52 ¿ ¿ ¿ 2 V =¿ 2g = 0.014 m = 14.00 mm
Graph of differential Piezometer head against Velocity head 6 5 4
Differential piezometer head,mm 3 2 1 0
0
2
4
6
8
10 12 14 16
velocity head,mm
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Figure 1.5 Graph of differential Piezometer head against Velocity head Discussions
Flow meter demonstration experiment is to demonstrate three different types of flow meter which are rotameter, venturi meter, orifice plate meter. In this experiment we has to determine both venturi and orifice meter flow rate and also the velocity head.In this experiment as well we can see the characteristic of three different types that is venturi meter, orifice meter, rotameter and also how the this device operating. From the theory for this experiment, we know that venturi meter is way more accurate compared to orifice and also rota meter. The result that we get was different from the theoretical value and this is because some error that occurred during conducting this experiment. One of the major factor that caused our data to be different with theoretical value is because parallax error which is the position of eyes during taken the manometer reading is wrong. Our eyes were not perpendicular when we took the reading. We have to make sure our eyes is at the right position when we take the data to prevent some error occurred. Next, we didn’t take the average data for this experiment which is more accurate compared to only one data that we have been calculated. Other than that, the apparatus is also need to improve as along the manometer and its needs to have more calibration in order to get more accurate reading or data. There were also bubbled occurred in the pipeline when we conducted this experiment and the bubbled occurred in the pipeline might have been influenced the reading that we have take and the calculation that we have calculated. For experiment 2, we also has determined the objective which is to investigate the lost coefficient of fluid through 90 degree elbow. From the graph that have been plotted, gradient (K) of the graph is 0.357 and for the theoretical value is 0.3 for Elbow flanged regular 90°. The percentage error for this experiment is less than 15% so our experiment can be considered successful. From the graph that we have plotted we notice that some different with the theoretical data which the graph should be in a straight line. This case caused by some error in the differential piezometer head that we take.
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Conclusion
For the conclusion, we conclude that the venturi meter is more accurate compared to orifice meter and also the rotameter. Based on theory of this experiment, the venturi meter is a precise device in measuring the flow rate of any fluid as it has the diverged portion that increases the velocity and reduces the friction loss compared to other two devices. We also have determine the flow rate measurement by utilizing three basic types of flow measuring techniques that is
rotameter, venturi meter and orifice meter and for the
experiment 2 we also has investigate the loss coefficient of fluid through 90 degree elbow. Form the calculation that we have made the percentage of error for the experiment 2 is less than 15% and our experiment were considered as successful experiment.
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Recommendation
There are so many ways to improve the data and to get a more accurate data that ensure that we have drain all water from the apparatus when not in use and the apparatus should be stored properly to prevent damage to occur. Other than that, any manometer tube that does not fill with water that indicates that the tapping or the connection of the manometer is blocked. To remove the obstacle, disconnect the flexible connection tube and blow through. Next, the apparatus should not be exposed to any shock and stresses during the experiment because it can affect the reading that we should read. Lastly, the students itself must fully understand before conducting the experiment.
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References 1. K.L. Kumar, “Engineering Fluid Mechanics”, 1st Edition, (1976), S. Chand & Company Ltd. 2. Lab manual, Faculty of Chemical Engineering, UiTM Shah Alam 3. https://www.coursehero.com/file/8491162/Flowmeter-Demonstration-full/
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Appendices
Figure 1.5 SOLTEQ Flow meter Measurement Apparatus (Model: FM 101
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