8/3/2019 weir real

1/21

UNIVERSITI TEKNOLOGI MARAFAKULTI KEJURUTERAAN KIMIACHEMISTRY ENG.LABORATORY

(CHE 315)

Checked by: Rechecked by:

No Title Allocated Marks (%) Marks (%)1. Abstract/Summary 52. Introduction 53. Aims/Objective 54. Theory 55. Procedure 36. Apparatus 57. Results 208. Calculations 109. Discussions 2010. Conclusions 10

11. Recommendations 512. References 513. Appendices 2

Total 100

NAME : AHMAD SHAZWAN BIN SHARIF MOHD

STUDENT NO : 2006254352EXPERIMENT : FLOWMETER DEMONSTRATION APPARATUS

DATE PERFORMED: 9 SEPTEMBER 2008

PROGRAMME CODE : DIPLOMA IN CHEMICAL ENGINEERING / EH 110

8/3/2019 weir real

2/21

CONTENTS

Title PageAbstract/Summary 3Introduction 4Objectives 5Theory 6Apparatus 7Procedures 8Results 9Calculations 11Discussions 15

Conclusions 16Recommendations 17References 18Appendices 19

ABSTRACT/SUMMARY

2

8/3/2019 weir real

3/21

This experiment which is flowmeter demonstration apparatus uses the specific hydraulic

model, which is the Flow Meter Test Rig (F1-21). This consists of venturi meter, variable

area meter, orifice plate installed in a series of configuration to allow direct comparisons.

The main objective of this experiment is to determine the operation and characteristics of

three different basic types of flow meter, including accuracy and energy losses by

measurement of flow rates and associated pressure losses. The three flow meters are

connected in series and uses timed volume collection to produce reference measurement

of flow rate. Hence, the application of the Bernoulli equation yields the result which

applies for both the venturi meter and the orifice plate. For venturi meter, Cd is 0.98 and

for the orifice plate, the Cd is 0.63. Next, the energy loss that occurs in pipe fitting(so-

called secondary loss) is commonly expressed in terms of a head loss, and can be

obtained from the monometer readings. For this experiment, head losses will becompared against the square of the flow rate used.

INTRODUCTION

3

8/3/2019 weir real

4/21

Fluid mechanics is the study of gases and liquids at rest and in motion. This area of

physics is divided into fluid statics, the study of the behavior of stationary fluids, and

fluid dynamics, the study of the behavior of moving, or flowing, fluids.

A variable area meter is a meter that measures fluid flow by allowing the cross sectionalarea of the device to vary in response to the flow, causing some measurable effect that

indicates the rate.

An orifice plate is basically a thin plate with a hole in the middle. It is usually placed in a

pipe in which fluid flows. As fluid flows through the pipe, it has a certain velocity and a

certainpressure. When the fluid reaches the orifice plate, with the hole in the middle, the

fluid is forced to converge to go through the small hole; the point of maximum

convergence actually occurs shortly downstream of the physical orifice, at the so-called

vena contracta point (see drawing to the right). As it does so, the velocity and the

pressure changes .An orifice gas meter consists of a straight length of pipe inside which

an orifice plate has been installed. The gas static pressure and its temperature must be

measured in addition to the differential pressure. Orifice meters are less accurate than

other measurement methods and they do not handle a large range of flow rates.

A tube with a decrease in the inside diameter that is used to increase the flow velocity ofthe fluid and thereby cause a pressure drop, used to measure the flow velocity (a

venturimeter) or to draw another fluid into the stream.

OBJECTIVE

4

http://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Vena_contractahttp://en.wikipedia.org/wiki/Velocityhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Vena_contracta

8/3/2019 weir real

5/21

The objective in this experiment is to determine the operation and characteristics of three

different basic types of flow meters, including the accuracy and energy losses.

THEORY

Application of the Bernoulli equation yields the following result which applies for both

the Venturi meter and the orifice plate.

5

8/3/2019 weir real

6/21

Volume flow rate p

A

A

ACQ dv

=2

1

2

2

2

Where hgp

=

2

2

And h : head difference in m determined from the

manometer readings for the appropriate meter

g : acceleration due to gravity 2s

m

Cd

: discharge coefficient for the meter

A1: area of the test pipe upstream of the meter (m

2)

A2

: throat area of the meter (m2

)

Use of a discharge coefficient, Cd

, is necessary because of the simplifying assumptions

made when applying the Bernoulli equations. Values of this coefficient are determined by

experiment; the assumed values used in the software are:

Venturi meter Cd

= 0.98

Orifice plate Cd

= 0.63

The energy loss that occurs in a pipe fitting (so-called secondary loss) is commonly

expressed in terms of a head loss (h, meters), and can be determined from the manometer

6

8/3/2019 weir real

7/21

readings. For this experiment, head losses will be compared against the square of the flow

rate used.

APPARATUS

1. The hydraulics bench which allows us to measure flow by timed volumecollection.

2. The F1-21 flow meter apparatus

3. A stopwatch to allow us to determine the flow rate of water.

7

8/3/2019 weir real

8/21

PROCEDURES

1. The flow meter test rig was placed on the bench and ensured that it is level

(necessary for accurate readings from the manometer).

2. Then, the inlet was connected to the bench supply and the outlet pipe into the

volumetric tank, and the end of the pipe was secured to prevent it moving about.

The pump was started and the bench valve and rig flow control valve were

opened.

8

8/3/2019 weir real

9/21

3. In order to blade air from the pressure tapping points and manometer, both of the

bench and test rig valves were closed, then the air bleed screw was opened and the

cap from the adjacent air valve was removed.

4. A length of small bore tubing from the air was connected to the volumetric tank.

Next, the bench was opened and flow was allowed through the manometer tubes

to purge them of air. Then, air bleed screw was tightened slightly to allow air to

be drawn into the top of the manometers tubes. Re-tighten the screw when the

manometers levels reach a convenient height.

5. Finally, all manometer levels on scale were checked at the minimum flow rate

(full-scale reading on the variable area meter). This level can be adjusted further

by using the air bleed screw or the hand pump supplier.

Taking a set of result

1. At a fixed flow rate, all manometers height was recorded and the variable area

meter reading and timed volume collection was carried out using the volumetric

tank. This is achieved by closing the ball valve and measuring (with a stopwatch)

the time taken to accumulate a known volume of fluid in the tank, as measured

from the sight glass.

2. The fluid was collected for at least one minute to minimize timing errors.

RESULTS

Test pipe areaA1

(m2)

OrificeAreaA2

VenturiAreaA2

Volumecollected

V

Timeto

collect

Variablearea

meter

H1(mm)

H2(mm)

H3(mm)

H4(mm)

H5(mm)

H6(mm

9

8/3/2019 weir real

10/21

(m2) (m2) (m3) t(sec)

reading(L/min)

7.92x10-4 3.14x10-4 1.77x10-4 0.004 58 5 228 215 225 220 178 177.92x10-4 3.14x10-4 1.77x10-4 0.004 42 7 244 221 235 232 180 187.92x10-4 3.14x10-4 1.77x10-4 0.004 31 9 254 218 240 236 182 18

7.92x10-4

3.14x10-4

1.77x10-4

0.004 27 11 262 215 245 238 185 187.92x10-4 3.14x10-4 1.77x10-4 0.004 21 13 282 210 258 245 192 19

H7(mm)

H8(mm)

Timedflow rate

Qt(m

3/s)

Variablearea flow

rateQa

(m3/s)

Orificeplate flow

rateQo

(m3/s)

Venturimeter flow

rateQv

(m3/s)

Variablearea %

flow rateerror(%)

Orificeplate %flow rate

error(%)

Venturemeter %flow rateerror (%)

168 175 6.89 x 10-5 8.33 x 10-5 1.00 x 10-4 8.97 x 10-5 20.89 45.14 30.19

165 164 9.52 x 10-5 1.17 x 10-4 1.207x10-4 1.19 x 10-4 22.89 26.78 25.00158 158 1.29 x 10-4 1.50 x 10-4 1.57 x 10-4 1.49 x 10-4 16.28 21.71 15.50152 155 1.48 x 10-4 1.83 x 10-4 1.81 x 10-4 1.71 x 10-4 23.65 22.29 15.54141 148 2.22 x 10-4 2.50 x 10-4 2.22 x 10-4 2.11 x 10-4 12.61 0 0

Variable area head

loss (Ha)(m)

Orifice plate Head

Loss (H0)(m)

Venturi meter Head

loss (HV)(m)

Timed flow rate

squared (Q12)

0.042 0.004 0.003 4.747 x 10-9

0.052 0.017 0.009 9.063 x 10-9

0.054 0.027 0.014 1.664 x 10-8

0.053 0.033 0.017 2.190 x 10-8

0.053 0.047 0.024 4.928 x 10-8

10

8/3/2019 weir real

11/21

CALCULATIONS

For variable area meter reading 5L/min,

Timed flow rate, Qt (m3/s)

Qt = V/t

11

8/3/2019 weir real

12/21

= 0.004 m3

58 s

= 6.89 x 10-5 m3/s

Variable area flow rate, Qa (m3/s)

= 5 L/min (1m3 / 1000 L) (1 min / 60 s)

= 8.33x 10-5 m3 /s

Orifice plate flow rate, Qo (m3/s)

Orifice Plate Flow RateA2 = 3.1410-4m2

A1 = 7.9210-4m2

Qo

=

And where = h6-h7= (0.63)(3.14x10-4) [2(9.81)(0.179-0.168)]

[1-(3.14x10-4/7.92x10-4)2]

=1.00210-4m3/s

Venturi meter flowrate, Qv (m3/s)

Venturi Meter Flow RateA2 = 1.7710-4m2

A1 = 7.9210-4m2

12

8/3/2019 weir real

13/21

Qv

Where, =And where, = h1-h2

= (0.98)(1.77x10-4) [2(9.81)(0.228-0.215)][1-(1.77x10-4/7.92x10-4)2]

= 8.97 x 10-5m3/s

Variable area % flowrate error (%)

(Qa Qt) x 100%

Qt

= (8.33 x 10-5 6.89 x 10-5 ) x 100%

6.89 x 10-5

= 20.89 %

Orifice plate % flowrate error (%)

(Qo Qt) x 100%Qt

= (1.00 x 10-4 6.89 x 10-5) x 100%

6.89 x 10-5

= 45.14%

13

8/3/2019 weir real

14/21

Venturi meter % flowrate error (%)

(Qv Qt) x 100%

Qt

= (8.97 x 10-5 6.89 x 10-5) x 100%

6.89 x 10-5

= 30.19%

Variable area head loss (Ha)

Ha = h4 h5

= (0.220 0.178) m

= 0.042 m

Orifice plate head loss (Ho)

Ho = h6 h8

= (0.179 0.175)m

= 0.004 m

14

8/3/2019 weir real

15/21

Venturi meter head loss (Hv)

Hv = h1 h3

= (0.228 0.225)m

= 0.003 m

Timed flow rate squared (Qt2)

= Qt2

= (6.89 x 10-5)2

= 4.747 x 10-9

Note : All calculations for 7,9,11 and 13 must be repeated according to the examples

of calculations above.

DISCUSSIONS

The operation and characteristics of three different basic types of flow meter can be

compared in this experiment. The time taken for filling up of 4L will increase with the

variable area meter reading.

From the results, variable area meter reading are set up 5 (L/min), 7 (L/min),

9(L/min),11 (L/min),13 (L/min) and the result shows that the orifice plate head lost are

larger than the venturi meter head lost. At 5L/min, the Qa is 8.33 x 10-5 m3/s, Qo is

1.00 x 10-4m3/s, Qv is 8.97 x 10-5m3/s and Qt is 6.89 x 10-5m3/s. The percent error is

calculated by (Q Qt)/Qt x 100 where Q is Qo, Qv, or Qa.

15

8/3/2019 weir real

16/21

To conclude, there are some mistakes when reading the manometer level or there are

pressure tapping in the manometer variable area, orifice plate and venturi meter, % flow

rate error of each flow rates is not very consistent. The % of flow rate error depends on

the flow rate in each characteristic of three different basic types of flow meter. The error

occurs because there are some mistake when conducting this experiment and the results

obtained are not consistent because when the value for each tubes H1, H2 and so on, the

readings were not taken accurately because the water inside the tube was still moving

when the reading value has been taken and suppose that the water inside should not

moving, so then the value can be taken.

Other than that, the equipments were not set up appropriately so the pressure tapping

inside the tube was not been released early and it affected the result obtained. As given in

the theory, the value for venturi coefficient is Cd = 0.98 and also for the orifice coefficientis Cd = 0.63. From the data obtained for time need to be taken for each flow rate, the time

decreases when the variable area meter reading increases. This is due to the dealing with

the larger amount of water and time, since a lot of water can flow to the reservoir so it

can fill the reservoir for a short period of time.The orifice plate and venturi meter head

loss increases when variable area meter reading increases. The times flow rate squared

increases because time needed to collect 4L of water decreases.

CONCLUSION

In the experiment of the venturi meter, variable area meter and the orifice plate are

installed in a series configuration to permit direct comparison. It means that it is possible

to determine the three different basic types of flow meter, thus knowing the accuracy and

energy losses.For 5L/min the head lost for orifice plate is 0.004m and the venturi meter head lost

is 0.003m.When the variable area reading were added up, the head lost of orifice is

0.017 m and for the venture meter head lost is 0.009 m. Next at every add up of the

variable area reading the head lost still increases. The orifice plate and venturi shows a

big variation in flow rate errors, but the percent value between orifice and venturi is

slightly same, meaning that the different is not too large.

16

8/3/2019 weir real

17/21

. At 5L/min, the Qa is 8.33 x 10-5 m3/s, Qo is1.00 x 10-4m3/s, Qv is 8.97 x 10-5m3/s

and Qt is 6.89 x 10-5m3/s. Then, calculate the same result for 7, 9, 11 and 13L/min.

RECOMMENDATION

1. Make sure the hydraulics bench is in good condition.

2. Make sure to check all manometer levels are on scale at the maximum flow rate.

3. Make sure that the ball valve is fully closed in the sink when the reading are taken

to avoid errors.

4. Read the results at the manometer carefully by using ruler to avoid parallax error.

17

8/3/2019 weir real

18/21

5. Make sure the stopwatch is controlled perfectly and ensure that the stopwatch

starts and stops when the volume reach 0L to 4L.

6. Make sure to collect the fluid for at least one minute to minimize timing error.

REFERENCES

1. Christine John Geankoplis, Transport Processes And Separation Process Principle(Includes Unit Operations), 4th Edition, Pearson Education International.

2. Coulson, J.M. and Richardson J.F., Chemical Engineering, Volume 2, Third Edition

(SI Units), Pergamon.

18

8/3/2019 weir real

19/21

3. Chemical Engineering Laboratory (CHE 315) Manual. Abd Jamil Lam, Chemical

Engineering Faculty, UiTM Shah Alam, Selangor.

4. www.wikipedia.com

APPENDICES

Test pipe areaA1

(m2)

OrificeAreaA2

(m2)

VenturiAreaA2

(m2)

Volumecollected

V(m3)

Timeto

collectt

(sec)

Variablearea

meterreading(L/min)

H1(mm)

H2(mm)

H3(mm)

H4(mm)

H5(mm)

H6(mm

7.92x10-4 3.14x10-4 1.77x10-4 0.004 58 5 228 215 225 220 178 177.92x10-4 3.14x10-4 1.77x10-4 0.004 42 7 244 221 235 232 180 187.92x10-4 3.14x10-4 1.77x10-4 0.004 31 9 254 218 240 236 182 187.92x10-4 3.14x10-4 1.77x10-4 0.004 27 11 262 215 245 238 185 18

19

8/3/2019 weir real

20/21

7.92x10-4 3.14x10-4 1.77x10-4 0.004 21 13 282 210 258 245 192 19

H7

(mm)

H8

(mm)

Timed

flow rateQt(m

3/s)

Variable

area flowrateQa

(m3/s)

Orifice

plate flowrateQo

(m3/s)

Venturi

meter flowrateQv

(m3/s)

Variable

area %flow rateerror(%)

Orifice

plate %flow rateerror(%)

Venture

meter %flow rateerror (%)

168 175 6.89 x 10-5 8.33 x 10-5 1.00 x 10-4 8.97 x 10-5 20.89 45.14 30.19165 164 9.52 x 10-5 1.17 x 10-4 1.207x10-4 1.19 x 10-4 22.89 26.78 25.00158 158 1.29 x 10-4 1.50 x 10-4 1.57 x 10-4 1.49 x 10-4 16.28 21.71 15.50152 155 1.48 x 10-4 1.83 x 10-4 1.81 x 10-4 1.71 x 10-4 23.65 22.29 15.54141 148 2.22 x 10-4 2.50 x 10-4 2.22 x 10-4 2.11 x 10-4 12.61 0 0

Variable area head

loss (Ha)(m)

Orifice plate Head

Loss (H0)(m)

Venturi meter Head

loss (HV)(m)

Timed flow rate

squared (Q12)

0.042 0.004 0.003 4.747 x 10-9

0.052 0.017 0.009 9.063 x 10-9

0.054 0.027 0.014 1.664 x 10-8

0.053 0.033 0.017 2.190 x 10-8

0.053 0.047 0.024 4.928 x 10-8

20

8/3/2019 weir real

21/21