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Examples
of Dry "Roughing" Pumps:
| Screw Pump.
Two opposing screws rotate to create gas flow. Direction of
flow is axial from inlet to exhaust. |
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| Hook &
Claw. Clawed rotors spin in opposite directions to
trap and compress gas and vapor. Gas flow is directed through
multiple stages and then exhausted. |
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Roots Mechanism.
Interlocking lobed rotors use positive displacement to move
gas and vapor.
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| Scroll Pump.
Uses two opposing scroll shaped disks. One is fixed while the
other rotates and uses an eccentric cam. Gases are trapped compressed
and moved towards the exhaust. |
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The above mentioned
pumps may be placed in series combinations for specific pumping
characteristics. Many manufacturers use multiple stages of the Hook
& Claw, and Roots device in a single pump.
Examples of High Vacuum Pumps
Turbo Molecular
Pump. Multiple stages of moving and fixed blades act
to "swat" gas molecules towards the exhaust. Gases
are then removed by a roughing pump.
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Cryo Pump.
Pumping is achieved by "freezing" gas or
vapor to very cold surfaces(Cryo-condensation). Light gases
are also adsorbed by charcoal (Cryo-sorption). Pump requires
periodic regeneration by warming the vanes.
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Examples of Oil Sealed Vacuum Pumps
| Rotary Vane.
An eccentrically mounted rotor and sliding vane "sweep"
gas from inlet to exhaust. The mechanism is immersed in oil
which acts to both lubricate and seal. |
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