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VACUUM PUMPING METHODS

Sliding Vane

Rotary Pump

Molecular

Drag Pump

Turbomolecular

Pump

Fluid Entrainment

Pump

VACUUM PUMPS

(METHODS)

Reciprocating

Displacement Pump

Gas Transfer

Vacuum Pump

Drag

Pump

Entrapment

Vacuum Pump

Positive Displacement

Vacuum Pump

Kinetic

Vacuum Pump

Rotary

Pump

Diaphragm

Pump

Piston

Pump

Liquid Ring

Pump

Rotary

Piston Pump

Rotary

Plunger Pump

Roots

Pump

Multiple Vane

Rotary Pump

Dry

Pump

Adsorption

Pump

Cryopump

Getter

Pump

Getter Ion

Pump

Sputter Ion

Pump

Evaporation

Ion Pump

Bulk Getter

Pump

Cold TrapIon Transfer

Pump

Gaseous

Ring Pump

Turbine

Pump

Axial Flow

Pump

Radial Flow

Pump

Ejector

Pump

Liquid Jet

Pump

Gas Jet

Pump

Vapor Jet

Pump

Diffusion

Pump

Diffusion

Ejector Pump

Self Purifying

Diffusion Pump

Fractionating

Diffusion Pump

Condenser

Sublimation

Pump

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Pressure EquivalentsAtmospheric Pressure (Standard) =

0

14.7

29.9760

760

760,000101,325

1.013

1013

gauge pressure (psig)

pounds per square inch (psia)

inches of mercurymillimeter of mercury

torr

millitorr or micronspascal

bar

millibar

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PRESSURE RANGES

RANGE

ROUGH (LOW) VACUUM

HIGH VACUUM

ULTRA HIGH VACUUM

PRESSURE

759 TO 1 x 10 -3 (mbar)

1 x 10 -3 TO 1 x 10 -8 (mbar)

LESS THAN 1 x 10 -8 (mbar)

(Page 17 manual)

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Viscous and Molecular Flow

Viscous Flow

(momentum transfer

between molecules)

Molecular Flow

(molecules move

independently)

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FLOW REGIMES

Viscous Flow:

Distance between molecules is small; collisions between

molecules dominate; flow through momentum transfer;generally P greater than 0.1 mbar

Transition Flow:Region between viscous and molecular flow

Molecular Flow:Distance between molecules is large; collisions between

molecules and wall dominate; flow through random motion;

generally P smaller than 10 mbar-3

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Conductance in Viscous

Flow

Under viscous flow conditions doubling thepipe diameter increases the conductance

sixteen times.The conductance is INVERSELY related to

the pipe length

(Page 28 manual)

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Viscous Flow

(Long Round Tube; air)

C = 1.38 x 102 x d4 x P1 + P2 (l/sec)

2l

d = diameter of tube in cm

l = length of tube in cm

P1 = inlet pressure in torr

P2 = exit pressure in torr

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Viscous Flow

(Long Round Tube;nitrogen)

EXAMPLE:d = 4 cm P1 = 2 torr

l = 100 cm P2 = 1 torr

C = 138 x d4 x P1 + P2 (liter/sec)

2l

C = 138 x 256 x 3 (liter/sec)

2100

C = 530 (liter/sec)

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Conductance in Molecular

Flow

Under molecular flow conditions doubling

the pipe diameter increases the conductance

eight times.The conductance is INVERSELY related to

the pipe length.

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Conductance in Molecular Flow

(Long Round Tube)

d = diameter of tube in cm

l = length of tube in cmT = temperature (K)

M = A.M.U.

C = 3.81 x d3 x T

Ml

(l/sec)

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Conductance in Molecular Flow

(Long Round Tube)EXAMPLE:

T = 295 K (22O

C)M = 28 (nitrogen)

C = 3.81 x d3 x T

Ml

(l/sec)

= 3.81 x d3 x 29528

(l/sec)

l

= 12.36 x d3

l

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EXAMPLE:

T = 295 K (22

O

C) d = 4 cmM = 28 (nitrogen) l = 100 cm

C = 3.81 x d3

xT

Ml (l/sec)

= 3.81 x d3 x295

28

(l/sec)

l

= 12.36 x d3

l= 12.36 x 0.64

= 7.9 (l/sec)

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SYSTEM

PUMP

C1

C2

Series Conductance

RT = R1 + R2

1 = 1 + 1C1 C2CT

1 = C1 + C2C1 x C2CT

CT = C1 x C2

C1 + C2

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GAS LOAD

Outgassing

Leaks

Virtual

Real

Backstreaming

Diffusion

Permeation

GAS LOAD (Q) IS EXPRESSED IN:

mbar liters per second

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Pumpdown Curve

Pressure

(mbar)

Time (sec)10

-11

10 1 10 3 10 5 10 7 10 9 10 11 10 13 10 15 10 17

10+1

10-1

10-3

10-5

10-7

10-9

Volume

Surface Desorption

DiffusionPermeation

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PUMP OPERATING RANGES

10-12 10-10 10-8 10-6 10-4 10-2 1 10+2P (mbar)

Rough VacuumHigh VacuumUltra High

Vacuum

Venturi Pump

Rotary Vane Mechanical PumpRotary Piston Mechanical Pump

Sorption Pump

Dry Mechanical Pump

Blower/Booster Pump

High Vac. PumpsUltra-High Vac. Pumps

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Rotary Vane, Oil-Sealed

Mechanical Pump

(Page 45 manual)

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Pump Mechanism

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OIL BACKSTREAMING

2

PRESSURE LEVELS: LESS THAN 0.2 mbar

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PUMP OPERATING RANGES

10-12 10-10 10-8 10-6 10-4 10-2 1 10+2

P (Torr)

Rough VacuumHigh VacuumUltra High

Vacuum

Roughing Pumps

Turbo Pump

Diffusion Pump

Cryo Pump

Ion Pump

Tit. Subl. Pump

Liquid Nitrogen Trap

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VACUUM SYSTEM USE

1

4

6

5

9

8

81

23

3a

45

6

7

8

9

Chamber

High Vac. PumpRoughing Pump

Fore Pump

Hi-Vac. ValveRoughing Valve

Foreline Valve

Vent Valve

Roughing Gauge

High Vac. Gauge

7

33a

2

8

2

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Oil Diffusion Pump

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Pump Construction

(Page 66 manual)

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How the Pump Works

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How the Pump Works

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Release of Vapors

(Page 67 manual)

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First stage vapors are

separated from others

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Pumping Speed

10-10 10--3 10--1

Pu

mpingSp

eed(Air)

1 2 3 4

Inlet Pressure (Torr)

Critical Point

1. Compression Ratio Limit

2. Constant Speed

3. Constant Q (Overload)

4. Mechanical Pump Effect

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Maximum Tolerable Foreline

Pressure

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VACUUM SYSTEM USE

LN2 COLD

TRAP

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Turbomolecular Pump

ROTOR BODY

HIGH PUMPING SPEED

HIGH COMPRESSION

EXHAUST

HIGH FREQ. MOTOR

INLET FLANGE

STATOR BLADES

BEARING

BEARING

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Rotor - stator assembly

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Pump Operation

Molecule V

Moving Wall with Speed V

Principle of the Turbomolecular Pump

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Roughing through the turbo

1

2

3

45

6

Chamber

Turbo Pump

Roughing Pump

Vent ValveRoughing Gauge

High Vac. Gauge

1

67

4

3

2

5

2