The fundamentals of vacuum technology

1. Vacuum physics Quantities, their symbols, units of measure and definitions . . . . . . . . . . . . . . . . . . . . . .9 1.1 Basic terms and concepts in vacuum technology . . . . . . . . . . .9 1.2 Atmospheric air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 1.3 Gas laws and models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 1.3.1 Continuum theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 1.3.2 Kinetic gas theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 1.4 The pressure ranges in vacuum technology and their characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.5 Types of flow and conductance . . . . . . . . . . . . . . . . . . . . . . . .15 1.5.1 Types of flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 1.5.2 Calculating conductance values . . . . . . . . . . . . . . . . . . . . . . .16 1.5.3 Conductance for piping and openings . . . . . . . . . . . . . . . . . . .16 1.5.4 Conductance values for other elements . . . . . . . . . . . . . . . . .18 2. Vacuum Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 2.1 Vacuum pumps: A survey . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 2.1.1 Oscillation displacement vacuum pumps . . . . . . . . . . . . . . . . .20 2.1.1.1 Diaphragm pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 2.1.2 Liquid sealed rotary displacement pumps . . . . . . . . . . . . . . . .20 2.1.2.1 Liquid ring pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 2.1.2.2 Oil sealed rotary displacement pumps . . . . . . . . . . . . . . . . . . .21 2.1.2.2.1 Rotary vane pumps (TRIVAC A, TRIVAC B, TRIVAC E, SOGEVAC) . . . . . . . . . . . .21 2.1.2.2.2 Rotary plunger pumps (E-Pumps) . . . . . . . . . . . . . . . . . . . . . .23 2.1.2.2.3 Trochoid pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 2.1.2.2.4 The gas ballast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 2.1.3 Dry compressing rotary displacement pumps . . . . . . . . . . . . .27 2.1.3.1 Roots pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 2.1.3.2 Claw pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 2.1.3.2.1 Claw pumps with internal compression for the semiconductor industry (ÒDRYVAC SeriesÓ) . . . . . . . . . . . . . . .33 2.1.3.2.2 Claw pump without internal compression for chemistry applications (ÒALLáexÓ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 2.1.4 Accessories for oil-sealed rotary displacement pumps . . . . . . .38 2.1.5 Condensers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 2.1.6 Fluid-entrainment pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 2.1.6.1 (Oil) Diffusion pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41 2.1.6.2 Oil vapor ejector pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 2.1.6.3 Pump fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44 2.1.6.4 Pump fluid backstreaming and its suppression (Vapor barriers, baffles) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44 2.1.6.5 Water jet pumps and steam ejectors . . . . . . . . . . . . . . . . . . . .45 2.1.7 Turbomolecular pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 2.1.8 Sorption pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50 2.1.8.1 Adsorption pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50 2.1.8.2 Sublimation pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 2.1.8.3 Sputter-ion pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 2.1.8.4 Non evaporable getter pumps (NEG pumps) . . . . . . . . . . . . . .53 2.1.9 Cryopumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54 2.1.9.1 Types of cryopump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54 2.1.9.2 The cold head and its operating principle . . . . . . . . . . . . . . . .55 2.1.9.3 The refrigerator cryopump . . . . . . . . . . . . . . . . . . . . . . . . . . . .56 2.1.9.4 Bonding of gases to cold surfaces . . . . . . . . . . . . . . . . . . . . . .56 2.1.9.5 Pumping speed and position of the cryopanels . . . . . . . . . . . .57 2.1.9.6 Characteristic quantities of a cryopump . . . . . . . . . . . . . . . . . .57 2.2 Choice of pumping process . . . . . . . . . . . . . . . . . . . . . . . . . . .60 2.2.1 Survey of the most usual pumping processes . . . . . . . . . . . . .60 2.2.2 Pumping of gases (dry processes) . . . . . . . . . . . . . . . . . . . . .62 2.2.3 Pumping of gases and vapors (wet processes) . . . . . . . . . . . .62 2.2.4 Drying processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64 2.2.5 Production of an oil-free (hydrocarbon-free) vacuum . . . . . . . .65 2.2.6 Ultrahigh vacuum working Techniques . . . . . . . . . . . . . . . . . .65 2.3 Evacuation of a vacuum chamber and determination of pump sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 2.3.1 Evacuation of a vacuum chamber (without additional sources of gas or vapor) . . . . . . . . . . . . . .66 2.3.1.1 Evacuation of a chamber in the rough vacuum region . . . . . . .67 2.3.1.2 Evacuation of a chamber in the high vacuum region . . . . . . . .68 2.3.1.3 Evacuation of a chamber in the medium vacuum region . . . . .68 2.3.2 Determination of a suitable backing pump . . . . . . . . . . . . . . . .69 2.3.3 Determination of pump-down time from nomograms . . . . . . . .70 2.3.4 Evacuation of a chamber where gases and vapors are evolved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71 2.3.5 Selection of pumps for drying processes . . . . . . . . . . . . . . . . .71 2.3.6 Flanges and their seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73 2.3.7 Choice of suitable valves . . . . . . . . . . . . . . . . . . . . . . . . . . . .73 2.3.8 Gas locks and seal-off fittings . . . . . . . . . . . . . . . . . . . . . . . . .75 3. Vacuum measurement, monitoring, control and regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76 3.1 Fundamentals of low-pressure measurement . . . . . . . . . . . . .76 3.2 Vacuum gauges with pressure reading that is independent of the type of gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77 3.2.1 Bourdon vacuum gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . .77 3.2.2 Diaphragm vacuum gauges . . . . . . . . . . . . . . . . . . . . . . . . . .77 3.2.2.1 Capsule vacuum gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77 3.2.2.2 DIAVAC diaphragm vacuum gauge . . . . . . . . . . . . . . . . . . . . .78 3.2.2.3 Precision diaphragm vacuum gauges . . . . . . . . . . . . . . . . . . .78 3.2.2.4 Capacitance diaphragm gauges . . . . . . . . . . . . . . . . . . . . . . .78 3.2.3 Liquid-filled (mercury) vacuum gauges . . . . . . . . . . . . . . . . . .79 3.2.3.1 U-tube vacuum gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79 3.2.3.2 Compression vacuum gauges (according to McLeod) . . . . . . .79 3.3 Vacuum gauges with gas-dependent pressure reading . . . . . .81 3.3.1 Spinning rotor gauge (SRG) (VISCOVAC) . . . . . . . . . . . . . . . .81 3.3.2 Thermal conductivity vacuum gauges . . . . . . . . . . . . . . . . . . .82 3.3.3 Ionization vacuum gauges . . . . . . . . . . . . . . . . . . . . . . . . . . .83 3.3.3.1 Cold-cathode ionization vacuum gauges (Penning vacuum gauges) . . . . . . . . . . . . . . . . . . . . . . . . . . .83 3.3.3.2 Hot-cathode ionization vacuum gauges . . . . . . . . . . . . . . . . . .84 3.4 Adjustment and calibration; DKD, PTB national standards . . . .86 3.4.1 Examples of fundamental pressure measurement methods (as standard methods for calibrating vacuum gauges . . . . . . .87 3.5 Pressure monitoring,control and regulation in vacuum systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88 3.5.1 Fundamentals of pressure monitoring and control . . . . . . . . . .88 3.5.2 Automatic protection, monitoring and control of vacuum systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89 3.5.3 Pressure regulation and control in rough and medium vacuum systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90 3.5.4 Pressure regulation in high and ultrahigh vacuum systems . . .92 3.5.5 Examples of applications with diaphragm controllers . . . . . . . .93 Table of Contents 4. Analysis of gas at low pressures using mass spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 4.2 A historical review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 4.3 The quadrupole mass spectrometer (TRANSPECTOR) . . . . . .96 4.3.1 Design of the sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .96 4.3.1.1 The normal (open) ion source . . . . . . . . . . . . . . . . . . . . . . . . .96 4.3.1.2 The quadrupole separation system . . . . . . . . . . . . . . . . . . . . .97 4.3.1.3 The measurement system (detector) . . . . . . . . . . . . . . . . . . . .98 4.4 Gas admission and pressure adaptation . . . . . . . . . . . . . . . . .99 4.4.1 Metering valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99 4.4.2 Pressure converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99 4.4.3 Closed ion source (CIS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99 4.4.4 Aggressive gas monitor (AGM) . . . . . . . . . . . . . . . . . . . . . . . .99 4.5 Descriptive values in mass spectrometry (specifications) . . . .101 4.5.1 Line width (resolution) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101 4.5.2 Mass range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101 4.5.3 Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101 4.5.4 Smallest detectable partial pressure . . . . . . . . . . . . . . . . . . .101 4.5.5 Smallest detectable partial pressure ratio (concentration) . . .101 4.5.6 Linearity range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102 4.5.7 Information on surfaces and amenability to bake-out . . . . . . .102 4.6 Evaluating spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102 4.6.1 Ionization and fundamental problems in gas analysis . . . . . .102 4.6.2 Partial pressure measurement . . . . . . . . . . . . . . . . . . . . . . .106 4.6.3 Qualitative gas analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . .106 4.6.4 Quantitative gas analysis . . . . . . . . . . . . . . . . . . . . . . . . . . .107 4.7 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108 4.7.1 Standard SQX software (DOS) for stand-alone operation (1 MS plus, 1 PC, RS 232) . . . . . . . . . . . . . . . . . . . . . . . . . .108 4.7.2 Multiplex/DOS software MQX (1 to 8 MS plus 1 PC, RS 485) . . . . . . . . . . . . . . . . . . . . . . .108 4.7.3 Process-oriented software Ð Transpector-Ware for Windows . . . . . . . . . . . . . . . . . . . . . . .108 4.7.4 Development software TranspectorView . . . . . . . . . . . . . . . .109 4.8 Partial pressure regulation . . . . . . . . . . . . . . . . . . . . . . . . . .109 4.9 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109 5 Leaks and their detection . . . . . . . . . . . . . . . . . . . . . . . . . .110 5.1 Types of leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110 5.2 Leak rate, leak size, mass flow . . . . . . . . . . . . . . . . . . . . . . .110 5.2.1 The standard helium leak rate . . . . . . . . . . . . . . . . . . . . . . . .112 5.2.2 Conversion equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112 5.3 Terms and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112 5.4 Leak detection methods without a leak detector unit . . . . . . .113 5.4.1 Pressure rise test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113 5.4.2 Pressure drop test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114 5.4.3 Leak test using vacuum gauges which are sensitive to the type of gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114 5.4.4 Bubble immersion test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115 5.4.5 Foam-spray test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115 5.4.6 Vacuum box check bubble . . . . . . . . . . . . . . . . . . . . . . . . . . .115 5.4.7 Krypton 85 test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115 5.4.8 High-frequency vacuum test . . . . . . . . . . . . . . . . . . . . . . . . .115 5.4.9 Testing with chemical reactions and dye penetration . . . . . . .115 5.5 Leak detectors and how they work . . . . . . . . . . . . . . . . . . . .116 5.5.1 Halogen leak detectors (HLD 4000, D-Tek) . . . . . . . . . . . . . .116 5.5.2 Leak detectors with mass spectrometers (MS) . . . . . . . . . . . .116 5.5.2.1 The operating principle for a MSLD . . . . . . . . . . . . . . . . . . . .117 5.5.2.2 Detection limit, background, gas storage in oil (gas ballast), floating zero-point suppression . . . . . . . . . . . . .117 5.5.2.3 Calibrating leak detectors; test leaks . . . . . . . . . . . . . . . . . . .118 5.5.2.4 Leak detectors with quadrupole mass spectrometer (ECOTEC II) . . . . . . . . . . . . . . . . . . . . . .119 5.5.2.5 Helium leak detectors with 180¡ sector mass spectrometer (UL 200, UL 500) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119 5.5.2.6 Direct-flow and counter-flow leak detectors . . . . . . . . . . . . . .120 5.5.2.7 Partial flow operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120 5.5.2.8 Connection to vacuum systems . . . . . . . . . . . . . . . . . . . . . . .121 5.5.2.9 Time constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121 5.6 Limit values / Specifications for the leak detector . . . . . . . . . .122 5.7 Leak detection techniques using helium leak detectors . . . . .122 5.7.1 Spray technique (local leak test) . . . . . . . . . . . . . . . . . . . . . .122 5.7.2 Sniffer technology (local leak testing using the positive pressure method) . . . . . . . . . . . . . . . . . . . . . . . . . . .123 5.7.3 Vacuum envelope test (integral leak test) . . . . . . . . . . . . . . .123 5.7.3.1 Envelope test Ð test specimen pressurized with helium . . . . .123 a) Envelope test with concentration measurement and subsequent leak rate calculation . . . . . . . . . . . . . . . . . . .123 b) Direct measurement of the leak rate with the leak detector (rigid envelope) . . . . . . . . . . . . . . . . . . . . . . . . .123 5.7.3.2 Envelope test with test specimen evacuated . . . . . . . . . . . . .123 a) Envelope = Òplastic tentÓ . . . . . . . . . . . . . . . . . . . . . . . . .123 b) Rigid envelope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123 5.7.4 ÒBombingÓ test, ÒStorage under pressureÓ . . . . . . . . . . . . . . .123 5.8 Industrial leak testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124 6 Thin film controllers and control units with quartz oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125 6.2 Basic principles of coating thickness measurement with quartz oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125 6.3 The shape of quartz oscillator crystals . . . . . . . . . . . . . . . . . .126 6.4 Period measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127 6.5 The Z match technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127 6.6 The active oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127 6.7 The mode-lock oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . .128 6.8 Auto Z match technique . . . . . . . . . . . . . . . . . . . . . . . . . . . .129 6.9 Coating thickness regulation . . . . . . . . . . . . . . . . . . . . . . . . .130 6.10 INFICON instrument variants . . . . . . . . . . . . . . . . . . . . . . . .131 7 Application of vacuum technology for coating techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133 7.1 Vacuum coating technique . . . . . . . . . . . . . . . . . . . . . . . . . .133 7.2 Coating sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133 7.2.1 Thermal evaporators (boats, wires etc.) . . . . . . . . . . . . . . . . .133 7.2.2 Electron beam evaporators (electron guns) . . . . . . . . . . . . . .134 7.2.3 Cathode sputtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134 7.2.4 Chemical vapor deposition . . . . . . . . . . . . . . . . . . . . . . . . . .134 7.3 Vacuum coating technology/coating systems . . . . . . . . . . . . .135 7.3.1 Coating of parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135 7.3.2 Web coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135 Table of Contents 7 7.3.3 Optical coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136 7.3.4 Glass coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137 7.3.5 Systems for producing data storage disks . . . . . . . . . . . . . . .137 8 Instructions for vacuum equipment operation . . . . . . . . .139 8.1 Causes of faults where the desired ultimate pressure is not achieved or is achieved too slowly . . . . . . . . . . . . . . . . .139 8.2 Contamination of vacuum vessels and eliminating contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139 8.3 General operating information for vacuum pumps . . . . . . . . .139 8.3.1 Oil-sealed rotary vacuum pumps (Rotary vane pumps and rotary piston pumps) . . . . . . . . . . .140 8.3.1.1 Oil consumption, oil contamination, oil change . . . . . . . . . . .140 8.3.1.2 Selection of the pump oil when handling aggressive vapors .140 8.3.1.3 Measures when pumping various chemical substances . . . . .141 8.3.1.4 Operating defects while pumping with gas ballast Ð Potential sources of error where the required ultimate pressure is not achieved . . . . . . . . . . . . . . . . . . . . . . . . . . . .142 8.3.2 Roots pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142 8.3.2.1 General operating instructions, installation and commissioning . . . . . . . . . . . . . . . . . . . . . . .142 8.3.2.2 Oil change, maintenance work . . . . . . . . . . . . . . . . . . . . . . .142 8.3.2.3 Actions in case of operational disturbances . . . . . . . . . . . . . .143 8.3.3 Turbomolecular pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143 8.3.3.1 General operating instructions . . . . . . . . . . . . . . . . . . . . . . . .143 8.3.3.2 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143 8.3.4 Diffusion and vapor-jet vacuum pumps . . . . . . . . . . . . . . . . .144 8.3.4.1 Changing the pump fluid and cleaning the pump . . . . . . . . . .144 8.3.4.2 Operating errors with diffusion and vapor-jet pumps . . . . . . .144 8.3.5 Adsorption pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144 8.3.5.1 Reduction of adsorption capacity . . . . . . . . . . . . . . . . . . . . . .144 8.3.5.2 Changing the molecular sieve . . . . . . . . . . . . . . . . . . . . . . . .144 8.3.6 Titanium sublimation pumps . . . . . . . . . . . . . . . . . . . . . . . . .145 8.3.7 Sputter-ion pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145 8.4 Information on working with vacuum gauges . . . . . . . . . . . . .145 8.4.1 Information on installing vacuum sensors . . . . . . . . . . . . . . .145 8.4.2 Contamination at the measurement system and its removal .146 8.4.3 The influence of magnetic and electrical fields . . . . . . . . . . . .146 8.4.4 Connectors, power pack, measurement systems . . . . . . . . . .146 9. Tables, formulas, nomograms, diagrams and symbols . .147 Tab I Permissible pressure units including the torr and its conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147 Tab II Conversion of pressure units . . . . . . . . . . . . . . . . . . . . . . . . .147 Tab III Mean free path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147 Tab IV Compilation of important formulas pertaining to the kinetic theory of gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148 Tab V Important values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148 Tab VI Conversion of pumping speed (volume flow rate) units . . . . .149 Tab VII Conversion of throughput (a,b) QpV units; leak rate units . . . . . . . . . . . . . . . . . . . . . . . . . . .149 Tab VIII Composition of atmospheric air . . . . . . . . . . . . . . . . . . . . . . .150 Tab IX Pressure ranges used in vacuum technology and their characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150 Tab X Outgassing rate of materials . . . . . . . . . . . . . . . . . . . . . . . . .150 Tab XI Nominal internal diameters (DN) and internal diameters of tubes, pipes and apertures with circular cross-section (according to PNEUROP). . . . . . . . . . . . . . . . . . . . . . . . . . . .151 Tab XII Important data for common solvents . . . . . . . . . . . . . . . . . . .151 Tab XIII Saturation pressure and density of water . . . . . . . . . . . . . . . .152 Tab XIV Hazard classificationof fluids . . . . . . . . . . . . . . . . . . . . . . . . .153 Tab XV Chemical resistance of commonly used elastomer gaskets and sealing materials . . . . . . . . . . . . . . . . . . . . . . . .155 Tab XVI Symbols used invacuum technology . . . . . . . . . . . . . . . . . . .157 Tab XVII Temperature comparison and conversion table . . . . . . . . . . .160 Fig. 9.1 Variation of mean free path l (cm) with pressure for various gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160 Fig. 9.2 Diagram of kinetics of gases for air at 20¡C . . . . . . . . . . . . .160 Fig. 9.3 Decrease in air pressure and change in temperature as a function of altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161 Fig. 9.4 Change in gas composition of the atmosphere as a function of altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161 Fig. 9.5 Conductance values for piping of commonly used nominal internal diameters with circular crosssection for molecular flow . . . . . . . . . . . . . . . . . . . . . . . . . . .161 Fig. 9.6 Conductance values for piping of commonly used nominal internal diameters with circular crosssection for molecular flow . . . . . . . . . . . . . . . . . . . . . . . . . . .161 Fig. 9.7 Nomogram for determination of pump-down time tp of a vessel in the rough vacuum pressure range . . . . . . . . . .162 Fig. 9.8 Nomogram for determination of the conductance of tubes with a circular cross-section for air at 20¡C in the region of molecular flow . . . . . . . . . . . . . . . . . . . . . . . .163 Fig. 9.9 Nomogram for determination of conductance of tubes in the entire pressure range . . . . . . . . . . . . . . . . . . . . .164 Fig. 9.10 Determination of pump-down time in the medium vacuum range taking into account the evolution of gas from the walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165 Fig.9.11 Saturation vapor pressure of various substances . . . . . . . . . .166 Fig. 9.12 Saturation vapor pressure of pump fluids for oil and mercury fluid entrainment pumps . . . . . . . . . . . . . . . . . . . . .166 Fig. 9.13 Saturation vapor pressure of major metals used in vacuum technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .166 Fig. 9.14 Vapor pressure of nonmetallic sealing materials (the vapor pressure curve for fluoro rubber lies between the curves for silicone rubber and Teflon). . . . . . . . . . . . . . . .167 Fig. 9.15 Saturation vapor pressure ps of various substances relevant for cryogenic technology in a temperaturerange of T = 2 Ð 80 K. . . . . . . . . . . . . . . . . . . . .167 Fig. 9.16 Common working ranges of vacuum pumps . . . . . . . . . . . . .167 Fig. 9.16a Measurement ranges of common vacuum gauges . . . . . . . .168 Fig. 9.17 Specific volume of saturated water vapor . . . . . . . . . . . . . . .169 Fig. 9.18 Breakdown voltage between electrodes for air (Paschen curve) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169 Fig 9.19 Phase diagram of water . . . . . . . . . . . . . . . . . . . . . . . . . . . .170 10. The statutory units used in vacuum technology . . . . . . . .171 10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171 10.2 Alphabetical list of variables, symbols and units frequently used in vacuum technology and its applications . . . . . . . . . .171 10.3 Remarks on alphabetical list in Section 10.2 . . . . . . . . . . . . .175 Table of Contents 8 10.4 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .176 10.4.1 Basic SI units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .176 10.4.2 Derived coherent SI units with special names andsymbols . .177 10.4.3 Atomic units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177 10.4.4 Derived noncoherent SI units with special names and symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177 11. National and international standards and recommendations particularly relevant to vacuum technology . . . . . . . . . . . . . . . . . . . . . . . . . . . .178 11.1 National and international standards and recommendations of special relevance to vacuum technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182 13. Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194