STUDY OF PERFORMANCE CHARACTERISTICS OF VAPOUR PUMPS
BY
DESH RAJ SHARMA
NATIONAL PHYSICAL LABORATORY NEW DELHI-110012
THESIS SUBMITTED TO DEPARTMENT OF PHYSICS, INDIAN INSTITUTE OF TECHNOLOGY, DELHI FOR PARTIAL FULFILMENT OF THE DEGREE OF
DOCTOR OF PHILOSOPHY APRIL, 1984
THESIS SUPLEVISORS
Xi ti oo SHA MA. D *PHIL OXON) HEWN ir
TACMDI
LIDtRESSURE ST
ANDAllik3 HAT
IDNAL PH IS I0 AL LABOR CORY.
NEW HEIR LA I 001 2
••'-' PRO L.L. CHO Alp PROPESSO OP PHYSI AID HEAD, ENERGY MITRE
MIAS MISTIME OP TECHEOI004 HAUZ ERAS*
MEW DELHI.110016.
ACKNOWLEDGEMEBTS ABSTRACT
CHAPTER I MEASUREMENT OF LOW PRKSSURE 1.1 Introduction
1.2 Basic Principle of McLeod
5
Gauge
1.3 The Chief Sources of Errors 6 and Their Elimination
1.4 The Bakeable McLeod Gauge 9
1.5
Details of Experimental System 12 1.6 Experimental Procedure 14 1.7 Study of Capillary Depreseion 16Phenomena
1.7.1 Correction due to Capillarity 19 in Wide Bore Reference Arm Tube
las
Study of Mercury Vapour Drag 27 Effect1.8.1 Theoretical Treatment
30
1.8.2 Experimental Results and 35 Discussion
1.9 Conclusion 39
Reforencee 41
CHAPT;!R II ilL;ASUREMENT 01 THROUGHPUT
45
2.1 Concept of Throughput 45 2.2 A Survey of Different Types
47
of Flovmeters
(a)Constant Pressure rimester
48
iJAM.A2A (b )Constant Vol.um Ploemeter 49 (o ):Liquid Displacement llowmeter 49 2.3 A Modified Stevenson Type 53
Flommeter
2.3.1 Operation 54
2.4 Investigation of a *s Type of 57 Relative Flowmeter
2.4.1 Design and Operation 58
2.4.2
Calibration Characteristics 602.4.3 Discussion 61
References 64
CHAFTidi III MEASUREMENT OF INTRINSIC SPEED AND 66 CRITICAL BACKING PRESSURE
SECTION As Measurement of Intrinsic 66 Speed
3.1 Introduot ion 66 3.1.1 Use of the Same Diameter Test Dome 69 3.2 Theoretical Aspects 72 3.3 Experimental Details and 74
Procedures
3.3.1 Test Dome Method 75 3.3.2 Conductance Tube Method 77 3.3.2.1 Measurement Procedure 79 3.4 Results and Discussion 81 SECTION Bs Study of Critical Backing 85
Pressure
3.5 Concept of Critical Backing 85 Pressure
3.6 Experimental Set-Up 88
3.6.1 Measuring Procedure 89 3.7 Calibration of Pirani Clues 92
Page No.
3.8 Results and Discussion
92
References
95
CHAPTER IV STUDY OF GAO BEAMING EFFi:CT INSIDE THI
TEST DOME 98
4.1 Introduction 98
4.2 Theoretical Consideration 104 4.2.1 Tabulated Gauge Connection 104 4.2.2 Orifice Gauge Connection 108 4.3 location of Pressure Gauge 111
for Sax: • S
(a) Tubulated Gauge 111 (b) Orifice Osage 112 4.4 Effect of Gauge Inlet Orientation 114 4.4.1 Values of LA for the Orientations 119
A and C
4.5 Details of Experimental set.up 121 and Procedure
4.6
Results 1264.6.1 Comparison of Measured old 126 Experimentally Computed Throughput
4.6.2 A New Approach to Intrinsio 128 Speed Measurement
4.6.3 Measurement of Molecular Conductance 130 4.6.4 Number of Gas Molecules/Sec 131
Crossing the Orifice of the Test Dome at any Position
4.6.5 Comparison of Experimentally 134 Measured and Theoretically
Determined Speeds
4.6.6 Effective Conductance and the Test 139 Dome Constant
4.6.7 Pressure Distribution in Axial 143 Direction
4.7 Discussions 144
4.8 Conclusion 148
References 152