UNIVERSITI TEKNOLOGI MARA

FAKULTI KEJURUTERAAN KIMIA

CHEMICAL ENGINEERING LABORATORY 1

(CHE 465)

NAME : CIK RUZAIMA BTE CHE RUSSLI

STUDENT NO. : 2007286952

EXPERIMENT :FLOWMETER DEMONSTRATION

DATE PERFORMED :22 FEBRUARY 2008

PREPARED FOR :CIK FAUZIAH

SEMESTER :2

PROGRAM / CODE ;BACHELOR OF ENGINEERING IN CHEMICAL ENGINEERING / EH220

No. Title Allocated marks % Marks %

1 Abstract/Summary 52 Introduction 53 Aims/Objectives 54 Theory 55 Procedures 36 Apparatus 57 Results 208 Sample of calculations 109 Discussions 2010 Conclusions 1011 Recommendation 512 References 513 Appendices 2

Total 100

Remark:

Checked by: Cik Fauziah Rechecked by:

1

TABLE OF CONTENT

2

No . Title Pages

1 Abstract/summary

2 Introduction

3 Aims/objectives

4 Theory

5 Procedures

6 Apparatus

7 Results

8 Calculations

9 Discussions

10 Conclusion

11 Recommendation

12 References

13 Appendices

ABSTARCT

This experiment has been done to measure the flow rate and associated pressure losses

with three devices which is venturi meter, orifice meter and variable area meter. First of all, we

must close the ball valve and measure the time taken to accumulate a known volume of fluid in

the tank, as measure from the sight-glass. Then, we record all the manometer height and the

variable area meter reading and carry out a timed volume collection using the volumetric tank.

To get the accurate reading, we must repeat this measurement (3x).

3

INTRODUCTION

Fluid mechanics has developed an analytical discipline from the application of the

classical laws of static, dynamics and thermodynamics, to situation in which fluids can be treated

as continuous media. The particular laws involved are those of conservation of mass; these laws

may be simplified in an attempt to describe quantitatively the behavior of the fluids.

The hydraulic bench service module, F1-10, provides the necessary facilities to support a

comprehensive range of hydraulic models each of which is designed to demonstrate a particular

aspect of hydraulic theory.

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

rig (F1-21). This consists of venture meter, variable area meter, and orifice plate installed in a

series of configurations to allow for direct comparisons.

Orifice

Nozzles

Venturi

4

21

Venturi meter

Venturi meter is a tube with constricted throat that increase velocity and decrease

pressure. Venturi meter is used to measure the flowrate of compressible and incompressible

fluid in a pipeline. When a fluid flows through a throat section, which has a smaller cross

sectional area than in a pipe, the velocity of the fluid through a throat is higher than in the pipe. If

velocity higher, pressure will drop. By measuring pressure drop, discharge may be calculated.

Beyond the throat the fluid is decelerated in a pipe of slowly diverging section (sometimes

referred to as a diffuser) in order to recover as much of the kinetic energy as possible. We must

know the principle of Bernoullies equation to understand the principles of venturi meter.

Orifice plate

The orifice meter is also used in measuring the flow rate of a reservoir or through a pipe.

The orifice meter consists of a flat plate with a circular hole drilled in it. There is pressure tap

upstream from the orifice plate and another just downstream.

Variable area meter.

The variable area flowmeter is a simple, reliable, inexpensive, and easy-to-install

flowmeter with low pressure drop and no electrical connection that givesa direct reading of flow

rate for a wide range of liquids and gases.

5

OBJECTIVES

To investigate and contrast the operation and characteristics of three different basics types of flow meter which venture, variable, and orifice including accuracy and energy losses.

To measure a pressure drop at different segment of device. To determine a flow rate through a pipe.

THEORY

6

Applications of the Bernoulli equation yield the following result, which applies for both the

Venturi meter and the Orifice plate.

Bernoulli equation:

P1 + V12 + Z1 = P2 + V2

2 + Z2ρg 2g ρg 2g

Z1=Z2

P1 + V12 = P2 + V2

2 ρg 2g ρg 2g

P1-P2 = V22 -V 1

2 ------------(1) ρg 2g

from: Q1=Q2

A1V1=A2V2

V1=A2V2 ------------(2) A1

(2) in (1) :

PI-P2 = V22 -(A 2V2/A1)2

ρg 2g

so;

V22 [1-(A 2/A1) 2 ] = ΔP

2g ρg

V2= 1 .√ ( 2ΔP) ---------------(3) √[1-(A2/A1)²] √ρ

Q=CdA2V2 ---------------------(4)

(3) in (4) ;

7

flow rate, Qv = CdA2 . √ ( 2∆P) √[1-(A2/A1)²] √p

where √ (2∆p) = √(2g∆h) √pwhere;

∆h : head difference in meter (m) from the manometer readings for the appropriate meter

g : acceleration due to gravity (m/s2)

Cd: discharge coefficient for meter

A1 : area of the test pipe upstream of the meter (m2)

A2 : throat area of the meter (m2)

Use of 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 term of e head loss (h, meters), and can be determined from the manometer

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

used. In addition, pressure loss for venturi and variable area flowmeter are low and for orifice

meter is medium.

PROCEDURES

8

Equipment set up

1. The flow meter test rig is placed on the bench and ensures that it is level (necessary for

accurate readings from the manometer).

2. The inlet pipe is connected to the bench supply and the outlet pipe into the volumetric

tank, and then secures the end of the pipe to prevent it moving around.

3. The pump is started and opens the bench valve and test rig flow control valve, to flush the

system.

4. The bench and test rig valves are closed to bleed air from the pressure tapping points and

manometers and open the air bleed screw and remove the cap from the adjacent air valve.

5. A length of small tubing is connected from the air valve to the volumetric tank.

6. The bench valve is opened and allows flow through the manometer tubes to purge them

of air.

7. Tighten air bleed screw and partly open the test rig flow control valve and pathly close

the bench valve.

8. The air bleed screw is opened slightly to allow air to be drawn into the top of the

manometer tubes.

9. Re-tighten the screw when the manometer levels reach a convenient height.

10. All the manometers are checked on the scale at the maximum flow rate (full- scale

reading on the variable area meter). These levels can be adjusted further by using the air

bleed screw or the hand pump supplied.

Taking a set of results

9

1. At fixed flow rate, all manometer and the variable area meter readings are recorded and

carry out a timed volume collection 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. At least one minute, fluid is collected to minimize timing errors.

3. This measurement is repeated twice to check for consistency and average the readings.

4. Ensure that the operating principle of each of these flow meters is understood.

10

1 2 3 4 5 6

Inlet Pipe Venturi Meter

Variable Area Meter

8 Bank Manometer 4

5

1 2 3

7 8

7 6 8

Orifice Meter

System Pressure Control Valve

Outlet Pipe

Air Bleed Valve

Bench Supply Valve

APPARATUS

Fig: Flow meter

11

In order to complete the demonstration a number of pieces of equipment is needed :

a) The Hydraulics Bench which allows the measurement of flow by timed volume

collection.

b) The F1-21 Flow Meter Apparatus.

c) A stopwatch to allow the determination of the flow rate of water.

The accessory is designed to be positioned on the side channels of the hydraulics bench channel.

The Venturi meter, variable area meter and the orifice plate are installed in a series configuration to permit direct comparison.

Flow through the test section is regulated using a flow control valve. This together with the bench control valve permits variation of the system static pressure.

Pressure tappings in the circuit are connected to an eight bank manometer which incorporates an inlet/outlet valve in the top manifold with facilities to connect a hand pump.

12

RESULTS

Test Pipe Area A1 (m2)

Orifice Area A2 (m2)

Venturi Area A2 (m2)

Volume collected V (m3)

Time to collect t (sec)

Variable Area Meter Reading (l/min)

1 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 113 22 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 55 43 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 32 64 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 25 85 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 19 106 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 16 127 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 14 148 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 12 169 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 9 1810 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 9 2011 7.92 x 10-4 3.14 x 10-4 1.77 x 10-4 0.003 8 22

h1 (mm) h2 (mm) h3 (mm) h4 (mm) h5 (mm) h6 (mm) h7 (mm) h8 (mm)1 228 227 227 226 174 174 173 1732 247 241 244 240 190 190 187 1883 234 220 227 227 173 174 165 1694 242 219 232 227 176 177 163 1695 253 215 239 233 178 180 157 1656 270 235 250 255 185 187 153 1647 284 210 257 240 188 193 145 1618 297 203 266 253 194 197 137 1589 321 196 283 257 201 207 125 15310 345 188 299 270 217 225 109 14811 376 170 323 280 220 231 95 140

13

Time flow rate Qt (m3/s)

Variable Area Flow Rate Qa

(m3/s)

Orifice Plate Flow rate Q0 (m3/s)

Venturi meter Flow rate Qv (m3/s)

1 2.65E-05 3.33E-05 3.02E-05 2.49E-052 5.45E-05 6.67E-05 5.23E-05 6.11E-053 9.34E-05 1.00E-04 9.05E-05 9.33E-054 1.20E-04 1.33E-04 1.13E-05 1.20E-045 1.58E-04 1.67E-04 1.45E-04 1.54E-046 1.88E-04 2.00E-04 1.76E-04 1.47E-047 2.14E-04 2.30E-04 2.09E-04 2.14E-048 2.50E-04 2.67E-04 2.34E-04 2.42E-049 3.33E-04 3.00E-04 2.73E-04 2.79E-0410 3.33E-04 3.33E-04 3.25E-04 3.12E-0411 3.75E-04 3.67E-04 3.52E-04 3.58E-04ave 1.95E-04 1.997E-04 1.726E-04 1.823E-04

Variable area % flow rate error (%)

Orifice plate % flow rate error (%)

Venturi meter % flow -rate error (%)

Variable area head loss (Ha)

Orifice plate head loss (H0)

Venturi meter head loss (Hv)

Timed flow rate squared (Qt

2)1 25.66 13.96 -6.038 0.052 0.001 0.001 7.02E-102 22.39 -4.037 12.11 0.050 0.002 0.003 2.97E-093 6.60 -3.105 -0.107 0.054 0.005 0.007 8.72E-094 10.83 -90.58 0.000 0.051 0.008 0.010 1.44E-085 5.70 -8.228 -2.532 0.055 0.015 0.014 2.50E-086 6.38 -6.383 -21.81 0.070 0.023 0.020 3.53E-087 7.48 -2.336 0.000 0.052 0.032 0.027 4.58E-088 6.80 -6.400 -3.200 0.059 0.039 0.031 6.25E-089 -9.90 -18.02 -16.21 0.056 0.054 0.038 1.11E-0710 0.00 -2.402 -6.306 0.053 0.077 0.046 1.11E-0711 -2.13 -6.133 -4.533 0.060 0.091 0.053 1.41E-07ave 7.26 -12.15 -4.42 0.0556 0.0315 0.0227 5.08E-08

14

SAMPLE OF CALCULATIONS

For the venturi meter

Upstream pipe diameter = 0.03175 m

Cross sectional area = A1 = 7.92 x 10-4 m2

Throat diameter = 0.015 m

Cross sectional area of throat = A2 = 1.77 x 10-4 m2

Upstream taper = 21 degrees

Down stream taper = 14 degrees

For the orifice plate

Upstream pipe diameter = 0.03175 m

Cross sectional area of upstream pipe= A1 = 7.92 x 10-4 m2

Throat diameter = 0.020 m

Cross sectional area of throat = A2 = 3.14 x 10-4 m2

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

Venturi meter reading = h1 – h2

Venturi loss = h1 – h3

Variable area meter = h4 – h5

Orifice plate reading = h6 – h7

Orifice plate loss = h6 – h8

15

Timed Flow rate, Qt (m3/s) = V = Volume Collected t Timed to collect = 0.003 m3/ 113s = 2.65 x 10-5 m3/s

Variable Area Flow Rate, Qa (m3/s) = Value from instrument reading (L/min) 60, 000 = 2(l/min) 60,000 = 3.33 x 10-5 m3/s

Variable Area Flow Rate, Qa (m3/s) = Value from instrument reading (L/min) 60, 000 = 2 L / min

60, 000 = 3.33 x 10ˉ5 m3/s

Orifice Plate Flow Rate, Qo (m3/s) = CdA2 √ 2g (h6 – h7) √[1-(A2/A1)²]

= (0.63) (3.14 x 10 -4 ) √ (2) 9.81 m/s) (0.001 m) √ 1 – (3.14 x 10 -4 ) 2 (7.92 x 10-4)2

= 3.02 x 10ˉ5 m3/s

Venturi Meter Flow Rate, Qv (m3/s) = CdA2 √ 2g (h1 - h2) √[1-(A2/A1)²]

= (0.98) (1.77 x 10 -4 ) √ (2) 9.81 m/s) (0.001m) √ 1 – (1.77 x 10 -4 ) 2 (7.92 x 10-4)2 = 2.49 x 10-5 m3/s

16

Variable Area % Flow Rate Error = (Qa – Qt) x 100 Qt

= (3.33 x 10ˉ5− 2.65 x 10ˉ5) x 100 2.65 x 10ˉ5

= 25.66%

Orifice Plate % Flow Rate Error = (Qo – Qt) x 100 Qt

= (3.02 x 10-5− 2.65 x 10ˉ5) x 100 2.65 x 10-5

= 13.96%

Venturi Meter % Flow Rate Error = (Qv – Qt) x 100 Qt

= (2.49 x 10-5− 2.65 x 10-5) x 100 2.65 x 10-5

= -6.038%

Variable Area Head Loss (Ha) = h4 - h5

= 0.226 m – 0.174 m = 0.052 m

Orifice Plate Head Loss (Ho) = h6 - h8

= 0.174 m – 0.173 m = 0.001 m

Venturi Meter Head Loss (Hv) = h1 - h3

= 0.228 m – 0.227 m = 0.001 m

Timed Flow Rate Squared (Qt2) = (Timed Flow Rate)2

= (2.65 x 10-5)2 = 7.02 x 10ˉ10 s2

17

DISCUSSIONS

From these experiments, we can see the three operations and characteristic of three

different types of flow meter which is venturi meter, orifice meter and variable area meter. We

also record all the readings during these experiments and we can see which one of the flow meter

give the accurate value. Besides that, we also determine the energy losses that occur in the three

differents flow meter.

After conduct these experiments, we are able to determine the value of flow rate of three

flowmeter, the value of flow rate error and the value of head loss. As the results from this

experiment, the average flow rate for venturi meter is 1.823 x 10-4 m3/s, 1.726 x 10-4 m3/s for

orifice meter and 1.997 x 10-4 m3/s for variable area meter.

Besides that, we also determine the value of flow rate error for the three flow meters.

From the results, the average flow rate error for variable area meter is 7.26%, -12.15% for orifice

meter and -4.42% for venturi meter. From the theory, the more efficiency of flow meter has a

less flow rate % error. So, from these results, the orifice has a less flow rate % error. The

accuracy of flow meter is depends on the flow rate % error.

From the experiment, we also obtain the value of head loss for the three flow meters.

From the theory, the venturi meter has a low head loss, continued by variable area meter and

then orifice meter. So, from the results, the value of head loss for venturi meter is 0.0227m,

orifice meter is 0.0315m and variable area meter is 0.0556m. We can say that this result is agreed

with the theory.

After calculate the flow rate % error, we noticed that there must be some errors. It is

because from the theory, venturi meter is a more accurate than orifice and variable area meter.

From the calculation, we determine that orifice meter is more accurate than others. Actually, it

should be the venturi meter. We found that one of the major factors that affect the readings is the

bubble in pipeline. Besides that, the position of eyes also gives effect to the manometer reading.

18

CONCLUSION

As a conclusion, we can say that the most accurate flow meter is a venturi meter. From

this experiment, we determine that the flow rate % error for venturi meter is higher than the

orifice meter. From the theory, the more efficiency of flow meter has a less flow rate % error.

19

RECOMMENDATION

After conduct this experiment, we can say that value of flow rate and the flow rate %

error are not follow the theorical results. From the theory, the most accurate flow meter is a

venturi meter. So, it means that the most efficiency flow meter has a less value of flow rate %

error. In this experiment, the value of flow rate % error for venturi meter is higher than the

orifice meter.

For the first recommendation for this experiment is make sure that there is no bubble in

the pipeline. The existence of bubble may cause the less accuracy of flow meter. The second is

make sure there is no small particles in the fluid because some of the devices are very sensitive

to these particles. Besides that, during record the manometer reading, make sure the position of

eyes is parallel to the level of reading.

20

REFERENCES

Laboratory manual 1, Faculty of Chemical Engineering, UiTM Malaysia Fluid mechanics, Fundamental and Applications, Yunus A. Cengel and John M.Cimbala,

Mc Graw Hill. Lecturer’s note from Pn Atikah bt Kadri Yahoo and Google search engines (keyword: flowmeter, venturi meter, orifice meter)

APPENDICES

21

Orifice plate

22

Venturi meter

Variable area meter

The eight bank manometer

23

24