《Vacuum Technology》

Chapter OneThe Nature of Vacuum1

1.1 What Is Vacuum?1

1.2 General Nature of a Gas1

1.3 The Atmosphere4

1.4 Units of Pressure7

1.5 Decimals and Powers of Ten9

1.6 Degrees of Vacuum11

1.7 Mean Free Path of a Gas11

1.8 Temperature Scales13

1.9 Effect of Pressure on a Gas15

1.10 Effect of Temperature on a Gas17

1.11 The General Gas Law19

1.12 Some Other Characteristics of Gases21

Chapter TwoVacuum Systems23

2.1 Elements of a Vacuum System23

2.2 Some Types of Vacuum Systems25

2.3 Quantity of Gas and Throughput26

2.4 Comparison with an Electric Circuit28

2.5 Comparison with Water Flow30

2.6 Resistances Connected in Series31

2.7 Resistances Connected in Parallel34

2.8 The Use of Logarithms36

2.9 Logarithmic Scales37

2.10 Pumping Speed41

2.11 Losses in Pumping Speed42

Chapter ThreeRotary Oil-Sealed Pumps49

3.1 The Nature of Such Pumps49

3.2 Pump Oils and the Oil System50

3.3 Ultimate Pressure52

3.4 Pumping Speed53

3.5 Effect of Connecting Lines56

3.6 Pump Size and Pump-Down Time—Method 162

3.7 Pump Size and Pump-Down Time—Method 265

3.8 Pump Size and Pump-Down Time—Method 367

3.9 Gas Handling Capacity of a Pump69

3.10 Some General Rules70

3.11 Setting Up Rotary Oil-Sealed Pumps70

3.12 Starting Rotary Oil-Sealed Pumps72

3.13 Stopping Rotary Oil-Sealed Pumps72

3.14 Maintenance Problems73

3.15 Use of a Nomograph76

Chapter FourVapor Pumps77

4.1 General Nature of Vapor Pumps77

4.2 Some Features of Diffusion Pumps79

4.3 Some Features of Ejector Pumps84

4.4 Mercury versus Oil87

4.5 Pump Performance89

4.6 Performance Characteristics of Diffusion Pumps92

4.7 Performance Characteristics of Ejector Pumps98

4.8 Migration of Pump Fluid98

4.9 Backing Pump Requirements100

4.10 Effect of Connecting Lines101

4.11 Pump-Down Time for Vapor Pumps103

4.12 Operating a Vapor Pump104

4.13Poor Operation or Failure of Vapor Pumps105

Chapter Five Some Other Types of Pumps109

5.1 Molecular Drag Pumps109

5.2 Roots Blower Pumps113

5.3 The Use of Getters as Pumps117

5.4 Gettering and Ionizing122

5.5 Pumps Using Evaporation and Ionization124

5.6 Pumps Using Sputtering and Ionization125

5.7 Cryopumping132

5.8 Other Sorption Pumps138

5.9 Water Aspirator,Toepler,and Sprengel Pumps139

Chapter SixMeasurement of Pressure142

6.1 The Nature of Vacuum Gauges142

6.2 Bourdon and Diaphragm Gauges143

6.3 U-Tube Manometers146

6.4 McLeod Gauges150

6.5 Pirani and Thermocouple Gauges162

6.6 Thermionic Ionization Gauges168

6.7 Cold Cathode Ionization Gauge176

6.8 Gauges Using Radioactive Materials181

6.9 Viscosity- and Radiometer-Type Gauges184

6.10 Use of Discharge Tube to Measure Pressure187

6.11 Gauges to Measure Very Low Pressures190

6.12 Calibration and Ranges of Vacuum Gauges193

Chapter SevenMeasurement of Pumping Speed198

7.1 Why Measure Pumping Speed?198

7.2 The Metered-Leak Method199

7.3 Positioning of Vacuum Gauge and Air Leak201

7.4 Admission of Air202

7.5 Vacuum Gauges205

7.6 Test Dome206

7.7 Rate-of-Rise Measurement207

7.8 Use of a Known Conductance211

Chapter EightProperties of Some Vacuum Materials216

8.1 The Elements216

8.2 Mercury and Water218

8.3 Liquids Used in Vacuum Practice219

8.4 Gases and Vapors222

8.5 Elastomers and Some Other Materials226

8.6 Glasses,Ceramics,and Metals Sealing to Them233

8.7 Copper and Copper Bearing Alloys236

8.8 Iron and Some of Its Alloys238

8.9 Molybdenum,Tantalum,and Tungsten240

8.10 Nickel and Its Alloys241

8.11 Vacuum Greases,Oils,Cements,and Waxes242

8.12 Some Drying and General Sorption Agents249

8.13 Temperature Data252

8.14 Alphabetical Listing252

Chapter NineCleaning Techniques262

9.1 The Nature of Contaminants262

9.2 General Methods of Reducing Contamination263

9.3 Descaling and Pickling Processes266

9.4 Electrolytic Cleaning and Polishing268

9.5 Cleaning of Mercury and Glass271

9.6 Miscellaneous Cleaning Procedures273

9.7 Cleaning by Degassing274

Chapter TenSome Fabrication Techniques279

10.1 Glass versus Metal279

10.2 Glass-to-Metal Seals281

10.3 Fabrication of Some Other Types of Seals283

10.4 Soldering285

10.5 Brazing288

10.6 Hydrogen Brazing298

10.7 Welding301

10.8 Electroplating305

10.9 Gasketed Joints309

10.10 Construction of Vacuum Vessels318

Chapter Eleven Baffles,Traps,and Valves322

11.1 The Use of Baffles and Traps322

11.2 Some Designs of Baffles324

11.3 Some Designs of Traps328

11.4 Operation and Maintenance of Baffles and Traps338

11.5 Liquid Nitrogen Filling Systems341

11.6 Pumping Losses in Baffles and Traps343

11.7 The Functions of Vacuum Valves349

11.8 Gate,Disk,and Flap Valves351

11.9 Globe,Needle,and Diaphragm Valves356

11.10 Stopcock,Plug,and Ball Valves359

11.11 Bakable Valves363

11.12 Some Special Valves367

11.13 Care and Maintenance of Valves369

Chapter TwelveSome Other Vacuum Components371

12.1 Common Static Seals Using Elastomers371

12.2 Sliding and Rotating Seals377

12.3 High Temperature Seals383

12.4 Low Temperature Seals388

12.5 Some Other Forms of Seals391

12.6 Couplings,Hose Clamps,etc.395

12.7 Electrical Lead-Throughs398

12.8 Leak Devices and Cut-Offs401

12.9 Protective Devices407

Chapter ThirteenConventional Vacuum Systems411

13.1 The Nature of Such Systems411

13.2 Basic Design Considerations412

13.3 Conductances of Components413

13.4 Designing a Vacuum System414

13.5 Setting Up a New Vacuum System422

13.6 Starting Up a Vacuum System423

13.7 Starting and Operating Tight Vacuum Systems426

13.8 Shutting Down a Vacuum System428

13.9 Maintenance Problems with Vacuum Systems429

13.10 The Small Vacuum Laboratory430

Chapter FourteenVery High and Ultra-High Vacuum Systems433

14.1 The Nature of Such Systems433

14.2 Small Very High Vacuum Systems434

14.3 Small Ultra-High Vacuum Systems436

14.4 Bake-Out Arrangement for Small Systems440

14.5 Bake-Out Procedure for Small Systems441

14.6 Large Low Pressure Vacuum Systems444

14.7 Bake-Out of Large Systems451

14.8 Construction Materials and Techniques453

14.9 Is There a Low Pressure Limit?454

Chapter FifteenFinding and Repairing Leaks456

15.1 When Is a System Tight?456

15.2 Sizes of Leaks457

15.3 Methods of Leak Detection458

15.4 Sealing Substance Outside,Pressure Change Inside460

15.5 Rate-of-Rise Measurements460

15.6 High Pressure Inside,Indicator Outside463

15.7 Spark Coils and Discharge Tubes466

15.8 Probe Materials with Standard Vacuum Gauges468

15.9 Unique Response of Vacuum Gauges469

15.10 Halogen Leak Detectors473

15.11 The Helium Leak Detector474

15.12 Sensitivity of Helium Leak Detectors475

15.13 Response and Clean-Up Times478

15.14 Vacuum Testing480

15.15 Pressure and Pressure-Vacuum Testing484

15.16 Commercial Helium Leak Detectors488

15.17 What Leak Detection System Should Be Used?493

15.18 Some General Rules for Leak Hunting497

15.19 Repairing Leaks499

Appendices503

AQuantities from Kinetic Theory of Gases503

B Mechanical,Ejector,and Diffusion-Ejector Pump Oils506

C Quantities and Relationships Useful in Vacuum Practice508

D Appearance of Discharges in Gases and Vapors at Low Pressures514

E Bibliography515

Index523