Agilent Technologies 969-8888, Instruction Manual

Page: 112 / 116

TECHNICAL INFORMATION
106/107 87-901-011-01
Purge and vent layout
HIGH VACUUM FLANGE CONNECTION
To connect the Turbo-V 3K-G pump to the ISO F
inlet flange position the integrated inlet screen -
centering ring with outer ring as shown in the fig-
ure.
Then fix the two flanges with the bolts as shown in
the following figures (12 x M10 steel bolts for ISO F
flange).
FORE-VACUUM PUMP CONNECTION
A flange KF 40 NW is available to connect the
Turbo-V 3K-G pump to the fore-vacuum pump. A
hose or vacuum approved pipe can be used. If a
rigid pipe is used, any vibration generated by the
mechanical pump must be eliminated through the
use of bellows.
NOTE
The Turbo-V 3K-G pump is characterized by its
high compression ratio also for oil vapors. When
using a mechanical oil-sealed pump, it is advisable
to install a suitable trap between the turbopump
and the fore-vacuum pump in order to prevent oil
backstreaming.
PUMP USED IN PRESENCE OF MAGNETIC
FIELDS
Magnetic fields induce eddy currents in the rotor of
a turbomolecular pump that tend to oppose to its
rotation.
The result is increased electrical power consump-
tion by the motor, most of which is dissipated in
the rotor.
Since the rotor is not in contact with the stator the
above power can leave the rotor mainly by radia-
tion and hence the rotor may be overheated while
static parts of the pump remain cool.
This effect is strongly dependant from the inten-
sity, time function and distribution of the magnetic
field.
In general, therefore, an increase in pump current
can be expected.
If this increase is lower than 50% of the current
value drawn by the motor in high vacuum opera-
tion, no particular problem should be expected.
However if the effect is greater, than the case
should be carefully reviewed by Varian’s specialist.
As a matter of fact, in case of high magnetic fields,
also important forces might be generated and ap-
plied to the rotor.
1. Purge gas line
2. Pressure
regulator
3. Purge and vent port
4. Forevacuum
pump
5. Turbopump
6. Water
line