A Measuring Device for temperature,humidity and distance from any object
Full description
Description complète
Calibration of Vernier CalliperFull description
Full description
Calibration of Bourdon Gauge
Calibration
Anil Chejara Roll No. 9003022 Group No. 4
CALIBRATION OF VENTURIMETER AND ORIFICEMETER BACKGROUND: A Venturi meter and an Orifice are both instruments used for measuring the rate of discharge for a fluid flowing in a pipe. These instruments are based on the pressure difference between between any two points on a tapering pipe through which the fluid is flowing depends on the change of levels and on the change in velocities and therefore on the volume rate of flow" Where the flow is led to narrow cross section, at which the velocity increase and hence a fall in the pressure occur. A Venturi Meter consists of a short converging conical tube leading to a cylindrical portion, called the throat, of smaller diameter of that of the pipeline, which is followed by a diverging section in which the diameter increases again to that of the main pipeline.
An Orifice Meter consists of an orifice plate which has an opening in it smaller than the internal diameter of the pipeline, placed in a flange connecting the two portions of the pipeline.
ME-313 IIT-Gandhinagar
Page 1
Actually the discharge rate occurring in the pipe is smaller for the calculated theoretical values that’s why a co efficient of discharge is to be evaluated for each instrument to be used then to calculate the actual rate of discharge. The expression for theoretical flow rate is obtained by applying the continuity equation and energy equation at inlet and throat section, and assuming the fluid to be ideal is given by:
AIM: The aim of the experiment is to determine the discharge coefficient of Venturi meter and orifice meter. APPARATUS:
Venturi meter and orifice meter with pressure tappings
Mercury manometer
Centrifugal pump, valves, etc.
Stop watch
PROCEDURE:
Make sure that the apparatus are free from Dust. Now close the drain valve. Open Flow Control Valve given on the discharge line and Control valve given on suction line. Set power output of the motor. Regulate Flow of water through pipe with the help of given Flow Control Valve. Regulate flow of water through venturimeter v enturimeter with the help of given flow control v alve. Measure the pressure difference between two sections in the venturimeter using mercury manometer.
Repeat the whole experiment for the flow through orifice meter.
Make sure that there is no water bubbles in the tube for measuring pressure heads. Measure Flow Rate using Measuring Tank and Stop Watch. When experiment is over, Switch off Pump and Power Supply. Drain water from sump tanks with the help of given drain valve
FORMULE AND DERIVATION: Assume an ideal fluid and applying Bernoulli’s Theorem at the inlet and throat of the device.
ME-313 IIT-Gandhinagar
Page 2
As there is no accumulation of water inside tube, from continuity we have:
is experimentally determined. The theoretical expression for -6
10
The equation implies that the graph between slope will give Co-efficient of discharge .
and
Observations & Calculations: Given Data: Venturimeter Data: Dia. at inlet =28mm Dia. at throat =14mm Orifice meter Data: Dia. at inlet =28mm Dia. at throat =14mm 2
2
Area of measuring tank: 40 x 25 cm = 1000 cm
ME-313 IIT-Gandhinagar
Page 3
is
will be straight line whose
OBSERVATION TABLE: A) Venturimeter Sr.no 1 2 3 4
ΔH(mm) 40 25 13 7
Height(cm) 10 10 10 10
Time(sec) 25.22 26.44 36.87 51.81
Sr.no
ΔH(mm)
Height(cm)
Time(sec)
1
72
10
22.97
2
50
10
27.84
3
24
10
40.84
4
8
10
63.53
B) Orifice meter
RESULTS: For venturimeter: venturimeter:
(mm)
Height (cm)
Time(sec)
1
40
10
25.22
2
25
10
26.44
3
13
10
36.87
4
7
10
51.81
Sr.no
ΔH
Q actual
Q th
Cd
0.0003965
0.00051928
0.763577
0.0003782
0.000410527
0.921291
0.0002712
0.000296035
0.916185
0.0001930
0.000217231
0.888516
Q th
Cd
For orifice meter: Sr.no 1 2 3 4
ΔH
Height(cm)
Time(sec)
10
22.97
0.0004354
0.000696688
0.624886
50
10
27.84
0.0003592
0.000580573
0.618691
24
10
40.84
0.0002449
0.000402233
0.608747
8
10
63.53
0.0001574
0.000232229
0.677804
(mm) 72
ME-313 IIT-Gandhinagar
Page 4
Q actual
GRAPHICAL ANALYSIS: A) Venturimeter
Flow Rate v/s ΔH 7 6 ) 5 . 0
5 4
m m 3 ( H Δ t2 o o R1
0 0.0000000
0.0002500
0.0005000
Flow Rate (m3/sec)
B) Orifice Meter 9 8 7 6 H ) 5 . 5 Δ 0 t m o o m R ( 4
3 2 1 0 0.0000000
0.0001000
0.0002000
0.0003000
0.0004000
0.0005000
Flow rate (m3/sec)
RESULTS: 1. Discharge co-efficient for Venturimeter = 0.873 2. Discharge co-efficient for orifice meter = 0.632 3. The value of discharge co-efficient for orifice is much less than the value for Venturimeter.
ME-313 IIT-Gandhinagar
Page 5
4. Based on the graph plotted above, the calibration of venturimeter is more accurate when measuring the rate of flow of a fluid through a pipe than an orifice meter.
5. The arrangement of Orifice Meter is much economical than the use of the Venturi meter, but as seen in this experiment the Venturi meter provide more accurate results that the Orifice meter, So the choice of which to use in a specified laboratory depends on the financial ability of the organization occupying the device and on the accuracy needed.
SOURCES OF ERRORS
Human error possible while taking reading.
Make sure that velocity of flow does exceed very much.
Flow rate of water may be varying during the experiment.
Make sure there is no bubble present in manometer.
Due to contamination in mercury manometer, our pressure reading may be affected.
Mercury was fluctuating; hence there can be error in measuring pressure readings.
