MYRA THERMO

8/4/2019 MYRA THERMO

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UNIVERSITI TEKNOLOGI MARA

FAKULTI KEJURUTERAAN KIMIA

CHEMICAL ENGINEERING LABORATORY

(CHE 465)

REMARKS:

Checked by :____________________Date:

NO. TITLE ALLOCATED

MARKS (%)

MARKS

1 Abstract 5

2 Introduction 5

3 Aims 5

4 Theory 5

5 Apparatus 5

6 Procedure 10

7 Results 10

8 Calculation 10

9 Discussion 20

10 Conclusion 10

11 Recommendation 5

12 Reference 5

13 Appendix 5Total marks 100

NAME : NURUL HUMAIRA BINTI HISHAMUDIN 2010853094

RAZZANA BINTI ROSLI 2010470454

MUHAMMAD ZULHAFIZI BIN KAMARUDDIN 2010440872

MUHAMMAD IMRAN BIN ISMAIL 2010451868

MUHAMMAD FAIZ

GROUP : 2D

EXPERIMENT : FLOWMETER

DATE PERFORMED : 23 MARCH 2011

SEMESTER : 2

PROGRAMME/CODE : EH 220 / CHE 465

SUBMIT TO : MADAM FUZIEAH


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TABLE OF CONTAIN

ABSTRACT .........................................................................................

INTRODUCTION ..........................................................................................

OBJECTIVE ..........................................................................................

THEORY ...........................................................................................

APPARATUS ..........................................................................................

PROCEDURE ..........................................................................................

RESULTS ...........................................................................................

CALCULATIONS ..........................................................................................

DISCUSSION ..........................................................................................

CONCLUSION ...........................................................................................

RECOMMENDATIONS ...........................................................................................

REFERENCES ..........................................................................................

APPENDIX ...........................................................................................


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ABSTRACT

Three most common devices used to measure the instantaneous are ventury meter,

orifices and variable area meter. In this demonstration Flow Meter Test Rig and the Hydraulics

Bench Service Module are used in this experiment.

The operation each of these meters operates on the principle that a decrease in flow area

in a pipe causes an increase in velocity that is accompanied by decrease in pressure. The

difference between them is a matter of cost, accuracy, and how closely actually operation obeys

the idealized flow assumption.


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INTRODUCTION

The specific hydraulic model that is concerned for this experiment is the flow meter test rig.

This consists of ventury meter, variable area meter, and orifice plate installed in a series to allow

for direct comparisons. Other devices typically used to determine flow rate are orifices and

nozzles, but the ventury tube has less head loss than either of these other methods due to its

streamlined design.

Orifice is used in this experiment can be used to measure the fluid flow through the difference in

pressure from upstream and downstream. The orifice plates are cheap and can be delivered for

almost any application in any material. Their accuracy is poor at low flow rates. Its accuracy

depends on an orifice plate in good shape, with a sharp edge to the upstream side. An orifice

flow meter is typically installed between flanges connecting two pipe sections (flanges are not

shown in the above drawings). The three standard pressure tapping arrangements are shown in

the drawings; the location of the pressure taps affects the discharge coefficient somewhat.

Flange pressure taps penetrate the flange and are at a standard distance of 1 inch (2.54 cm) from

either side of the orifice. For corner taps or D and D/2 taps, the pressure tap locations are as

shown.

For ventury tube it is used commonly in applications where it is lower pressure drop than the

orifice plate can provide. The venturi meter is used to measure the rate of flow in a pipe. It is

generally consisting of an upstream portion, which is the same size as the pipe, contains a

piezometer ring for measuring static pressure. It also consists of a converging conical region, a

cylindrical throat containing a piezometer ring and gradually diverging conical region leading to
http://www.lmnoeng.com/orifice.htmhttp://www.lmnoeng.com/nozzles.htmhttp://www.lmnoeng.com/nozzles.htmhttp://www.lmnoeng.com/orifice.htm


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a cylindrical section the size of the pipe. A differential manometer s attached to the two

piezometer rings. The size of a venturi meter is specified by the pipe and throat diameter.

The classical Venturi tube (also known as the Herschel Venturi tube) is used to determine flow

rate through a pipe. Differential pressure is the pressure difference between the pressure

measured at D and at d. . The venturi tube is similar to an orifice meter, but it is designed to

nearly eliminate boundary layer separation, and thus form drag. The change in cross-sectional

area in the venturi tube causes a pressure change between the convergent section and the throat,

and the flow rate can be determined from this pressure drop.

Variable head meters work on the principle that a variation of the flow rate through a

constriction with a constant cross-sectional area causes a pressure drop suffered by the fluid as it

flows through the constriction. The pressure drop is related to the flow rate, and hence variations

of the pressure drop can be used to measure variations in the flow rate.

In order to control these processes and to calculate mass balances for these processes it is

important to be able to accurately measure the flow rate of these fluids as they move through

pipes, conduits, or channels.

The Variable Meter consists of an enlarging transparent tube and a metering that is displaced

upward by the upward flow of fluid through the tube. The tube is graduated to read the flow

directly. Notches in the float cause it to rotate and thus maintain a central position in the tube.

The greater the flow, the higher the position the float assumes.


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OBJECTIVE

To investigate the oprtion and characteristics of three type of flow meter,including accuracy and

energy loses.

THEORY

Recall Bernoulli equation, which expresses the principle of conservation of linear momentum

under special circumstances :

2

2

221

2

11

22gz

VPgz

VP

This was derived with the following assumptions:

1. Steady flow

2. Incompressible flow

3. Flow along a streamline

4. No frictional forces

In addition, we shall assume . Therefore, we have

22

2

22

2

11 VPVP

Let us consider the continuity equation (conservation of mass) and limit it to the same

assumption as above. Then we have

2211 AVAV where

4

2

1

1

DA

4

2

2

2

DA (3)

2

2

1

1

2

1

2

D

D

A

A

V

V(4)


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Solving for from equation (2) 2

1

2

1

2

2

112

V

V

VPP

Substituting for from equation (4) 2

1

4

2

1

2

112

D

D

VPP

Noting that

11 AVm

1

1A

mV

2

1

2

1A

mV

4

2

1

2

1

2

12 12 D

D

A

mPP

(5)

or pressure at any location x is given by

4

1

2

1

2

1 12 xD

D

A

mPxP

(6)

or, sinceg

xPxh

)()(

one can write

4

1

2

1

2

2

1)(

12

)(xD

D

Ag

mhxh

(7)

Hence the pressure head at any location along the test section can be expressed in term of the

pressure at a reference location (inlet).


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APPARATUS


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PROCEDURE

A. EXPERIMENT SET UP1. The flowmeter test rig is being placed on the bench and ensured it is level (necessary for

accurate readings from the manometer).

2. The inlet pipe are connected to bench supply and the outlet pipe are connected into thevolumetric tank.

3. Both end of inlet and outlet pipes are secured to prevent it moving about.4. The pump is turned on. The bench valve and the test rig flow control valve are opened to

flush the system.

5. Both the bench and test rig valves is closed to bleed air from the pressure tapping pointsand manometers and then the air bleed screw is opened by removing the cap from the

adjacent air valve.

6. A length of small-bore tubing is connected from the air valve to the volumetric tank.7. The bench valve is opened to allow flow through the manometer tubes to purge them of

air.

8. The air bleed screw is then tightened and the test rig flow control valve is opened partlyand the bench valve is closed partly.

9.

The air bleed screw is slightly opened to allow air to be drawn into the top of themanometer tubes and the screw is then re-tightened when the manometer levels reach a

convenient height.

10.All manometer levels must be checked to be on scale at the maximum flowrate.

B. TAKING SET OF RESULTS1. All manometer heights, the variable area meter reading and a timed volume collection

were recorded at a fixed flow rate by using the volumetric tank.

2. The ball valve is closed to achieved desired result and the time taken by using astopwatch was measured.

3. The time taken was used to accumulate a known volume of fluid in the tank, as measuredfrom the sight glass.


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4. Steps 1-3 are repeated by increasing the volume flowrate gradually until the variable areaflowmeter indicates full scale.

5. All the readings are recorded and tabulated.6. Calculations are being performed.


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RESULTS

Flow

rate

(L/min)

Time

taken

Volume

Collected

h1 h2 h3 h4 h5 h6 h7 h8

2 1.07.66 3 230 226 230 226 175 175 174 175

4 0.47.30 3 240 230 235 230 177 180 170 175

6 0.28.94 3 250 227 240 235 180 183 170 174

8 0.19.75 3 260 225 245 236 184 186 165 172

10 0.15.79 3 273 220 254 243 186 190 157 169

12 0.13.53 3 284 216 264 248 191 195 150 165

14 0.11.31 3 308 210 276 259 199 204 140 16116 0.10.87 3 329 200 290 268 205 213 128 155

18 0.08.47 3 350 192 305 278 214 220 115 150

20 0.06.72 3 350 180 320 288 220 230 103 145

22 0.06.19 3 395 165 335 300 230 243 90 140


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CALCULATIONS

The manometers are connected so that the following pressure differences can be obtained.

h1h

2Venturi meter reading

h1h3 Venturi loss

h4h5 Variable area head loss

h6h7 Orifice plate reading

h6h8 Orifice plate loss

For rate 2 (L/min)

Flow rate: Qt=

=

=4.4810-5

m3/s

Variable area flow rate Qa=

=3.3310-5

m3/s

Orifice plate flow rate Qo=

=()

=3.02m3/s


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Venturi meter flow rate, Qv=

=()

=4.99m3/s

CALCULATION FOR HEAD LOSS

Variable Area Head Loss,54

hhHa

=226-175

=51 mm

Orifice Plate Head Loss, 860 HHH

Ho = 175-175

= 0 mm

Venturi Plate Head Loss, 31 HHHv

Hv = 230-230

= 0 mm

Timed Flow Rate Squared, ( Qt ) = (4.478x10-5 )

=2.01 x 10

-9


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SAMPLE ERROR CALCULATION

Variable area % flow rate error

100%

=

= -25.67%

Orifice area % flow rate error

=

100%

= -32.59%

Venturi area% flow rate error

=

=11.38%


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Flow

rate(L/mi

n)

Timed

flowrate,

Qt

(m3/s)

Varia

blearea

flow

rate,

Qa(m

3/s)

Orific

e plateflow

rate,

Qo(m

3/s)

Ventu

rimeter

flow

rate,

Qv(m

3/s)

Varia

blearea

%

flow

rate

error

Orifi

ceplate

%

flow

rate

error

Vent

urimeter

%

flow

rate

error

Varia

blearea

head

loss

(mm)

Orifi

ceplate

head

loss

(mm

)

Vent

urimeter

head

loss

(mm)

Timed

flowrate

square

d (Qt2)

2 4.48

10-5

3.33

10-5

3.02

10-5

4.99

10-5

-

25.67

%

-

32.59

%

11.38

%

51 0 0 2.01

10-9

4 6.38

10-5

6.67

10-5

9.55

10-5

7.88

10-5

4.55% 49.69

%

23.51

%

53 5 5 4.07

10-9

6 1.07

10-4

1.00

10-4

1.09

10-4

1.20

10-4

-

6.54%

1.87

%

12.15

%

55 9 10 1.15

10-8

8 1.58

10-4

1.33

10-4

1.38

10-4

1.47

10-4

-

15.82

%

-

12.66

%

-

6.96

%

52 14 15 2.49

10-8

10 2.00

10-4

1.67

10-4

1.73

10-4

1.82

10-4

-

16.5%

-

13.5

%

-9% 57 21 19 4.00

10-8

12 2.31

10-4

2.00

10-4

2.03

10-4

2.06

10-4

-

13.42

%

-

12.12

%

-

10.82

%

57 30 20 5.34

10-8

14 2.73

10-4

2.33

10-4

2.71

10-4

2.47

10-4

-

14.65

%

-

0.73

%

-

9.52

%

60 43 32 7.45

10-8

16 3.00

10-4

2.67

10-4

3.59

10-4

2.83

10-4

-11% 19.67

%

-

5.67

%

63 58 39 9.00

10-8

18 3.75

10-4

3.00

10-4

3.09

10-4

3.13

10-4

-20% -

17.6

%

-

16.53

%

64 70 45 1.41

10-7

20 5.00

10-4

3.33

10-4

3.40

10-4

3.25

10-4

-

33.4%

-32% -35% 68 85 30 2.50

10-7

22 5.00

10-4

3.67

10-4

3.73

10-4

3.78

10-4

-

26.6%

-

25.4

%

-

24.4

%

70 103 65 2.50

10-7


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DISCUSSION

Throughout the experiment that was conducted, the aim of the experiment is to determine

which one of the devices has higher accuracy in measuring the flow rates. However, the

results of the experiment is disagreed by showing that the theory that the venturi meter hashighest accuracy in measuring the flow rate of fluids, but the different between head loss of

the venturi meter and the orifice meter is 0 m. The efficiency of orifice meter obeyed the

theory where the head loss produced by the variable area meter is 0.051 m compared to the

orifice meter with no head loss for the first readings. Differences in reading of the three

devices may occur which were caused by the air bubbles that was trapped in the tube while

we conducting the experiment.

When conducting the experiment, there is an error detected through measuring the flow rate

as the data obtained is not accurate enough. This error occur as we read the data manually and

not by digital measurement. All the data is read and observed at the scale of each

measurement. There are 8 tubes of measurement that must be taken at equivalent time. So,

there will be error in collecting the data because we only able to read the data one by one

from one tube to another tube. Therefore, there is a slight difference in time to take the

measurement and this will affected the result of data.

After calculating the percentage errors, we noticed that there must be some errors regarding

the value of measuring the height or regarding the time taken. But we would like to say that

our objectives of this experiment are fulfill even the accuracy of these three meters is slightly

deviated. We have discussed the reasons and way to reduce these errors by suggesting some

way to determine accurate head loss pressure of each instrument.

According to our aims, we have achieved about 50% to fulfill these objectives of experiment.

However, as a human, it is not an easy job to get 100% accuracy in determining these

characteristics of these meters, which are Orifice, Venturi, and Variable Area meters. This

error is detected while measuring the height of manometers with the help of stopwatch to

measure the time interval. Some other errors are caused of less exposure to these meters. The

human errors were inaccurate in taking manometers reading and also the time reading. This

will occur when the position of eyes are not accurate to the normal of the meter reading.


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We also have to make sure that there is no air bubbles inside the pipelining and manometers

of the flow meter before start taking any reading. To ensure this, air must be purged out of the

system. In order to achieve this, the flow valves on the flow meter fig must be opened slowly.

Thus the flow valves are flow slowly, the bubbles in the rig flow meter can be removed.

Besides that, this flow meter must use a digital meter to have more accurate value for the

entire meter.


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CONCLUSION

This experiment was performed to investigate and evaluate the operation and characteristics

of venturi and orifice flow meters, through actual results and compare with the theoretical

calculations. Overall, we conclude that results of the experiment is disagreed by showing thatthe theory that the venturi meter has highest accuracy in measuring the flow rate of fluids.

However, the difference of head loss of the venturi meter and the orifice meter is 0 m. On the

other hand, the efficiency of orifice meter obeyed the theory. The percentage error that we

calculate display us that we have achieved 50% due to some errors in taking the height of the

manometers. Note that if the static pressure in the system is excessive, Eg. with the bench

flow control valve fully open and the outlet flow control valve almost closed, it will not be

possible to use the hand pump to lower the levels in the manometer tubes. The valves should

be adjusted to provide the required flowrate at a lower static pressure. On top of that, after the

operation we should make sure that all the water is being drained out from the pipework.

Finally, this experiment has equiped us with the theory of fluid mechanics and has developed

an analytical discipline from the application of the classical laws of statics, dynamics and

thermodynamics.

RECOMMENDATIONS

1. Air must completely purge out from the tube to avoid bubbles presence. It is due tothe accuracy of the flowmeter.

2. Make sure there is no small particle in the water that we used.3. Make sure the eye position is correct to the meniscus. It is because to avoid parallax

error.


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REFERENCES

1. www.engr.iupui.edu/me/courses/me310lab/experiment12.pdf2. www.d.umn.edu/~dlong/exflwmtr.pdf3.

http://www.lmnoeng.com/venturi.htm

4. http://www.answers.com/topic/flow-meter5. http://www.csus.edu/indiv/h/hollandm/ce135/Present/FlowMetr/FMSingle.html6. www.engin.brown.edu/courses/en81/Lab%20Stuff/Lab2%20Fall...7. www.csupomona.edu/~padashner/313/FlowMeasurement.pdf8. http://www.ckgas.com/html/rotameters-basic-flowmeter-principles.html
http://www.engr.iupui.edu/me/courses/me310lab/experiment12.pdfhttp://www.engr.iupui.edu/me/courses/me310lab/experiment12.pdfhttp://www.engr.iupui.edu/me/courses/me310lab/experiment12.pdfhttp://www.engr.iupui.edu/me/courses/me310lab/experiment12.pdfhttp://www.d.umn.edu/~dlong/exflwmtr.pdfhttp://www.d.umn.edu/~dlong/exflwmtr.pdfhttp://www.d.umn.edu/~dlong/exflwmtr.pdfhttp://www.d.umn.edu/~dlong/exflwmtr.pdfhttp://www.lmnoeng.com/venturi.htmhttp://www.lmnoeng.com/venturi.htmhttp://www.answers.com/topic/flow-meterhttp://www.answers.com/topic/flow-meterhttp://www.csus.edu/indiv/h/hollandm/ce135/Present/FlowMetr/FMSingle.htmlhttp://www.csus.edu/indiv/h/hollandm/ce135/Present/FlowMetr/FMSingle.htmlhttp://www.engin.brown.edu/courses/en81/Lab%20Stuff/Lab2%20Fallhttp://www.engin.brown.edu/courses/en81/Lab%20Stuff/Lab2%20Fallhttp://www.engin.brown.edu/courses/en81/Lab%20Stuff/Lab2%20Fallhttp://www.engin.brown.edu/courses/en81/Lab%20Stuff/Lab2%20Fallhttp://www.csupomona.edu/~padashner/313/FlowMeasurement.pdfhttp://www.csupomona.edu/~padashner/313/FlowMeasurement.pdfhttp://www.csupomona.edu/~padashner/313/FlowMeasurement.pdfhttp://www.csupomona.edu/~padashner/313/FlowMeasurement.pdfhttp://www.ckgas.com/html/rotameters-basic-flowmeter-principles.htmlhttp://www.ckgas.com/html/rotameters-basic-flowmeter-principles.htmlhttp://www.ckgas.com/html/rotameters-basic-flowmeter-principles.htmlhttp://www.csupomona.edu/~padashner/313/FlowMeasurement.pdfhttp://www.engin.brown.edu/courses/en81/Lab%20Stuff/Lab2%20Fallhttp://www.csus.edu/indiv/h/hollandm/ce135/Present/FlowMetr/FMSingle.htmlhttp://www.answers.com/topic/flow-meterhttp://www.lmnoeng.com/venturi.htmhttp://www.d.umn.edu/~dlong/exflwmtr.pdfhttp://www.engr.iupui.edu/me/courses/me310lab/experiment12.pdf


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APPENDICES


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