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Fore-vacuum Pump Connection
A flange KF 16 NW is available to connect the
Turbo-V250SF 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 me-
chanical pump must be eliminated through the use
of bellows.
NOTE
The Turbo-V250SF is characterized by its high
compression ratio also for oil vapors. When using a
mechanical oil-sealed pump, it is advisable to in-
stall a suitable trap between the turbopump and the
fore-vacuum pump in order to prevent oil back-
streaming.
Electrical Connection
The turbopump is connected to the controller
through an 6-pin connector. Pins B, C and D are
the 3-phase supply to the motor, pins A and F are
connected to the temperature sensor (NTC type,
30 KΩ resistance at 25n C) and pin E is connected
to the pump earth.
If the temperature sensor is disconnected, the
pump will not start. To prevent damage to the
pump when the temperature exceeds 60n C, the
sensor automatically cuts out the power supply.
PUMP USED WITH CORROSIVE GASES
To prevent damage to the bearings, an inert gas
must flow into the pump body around the upper
bearing towards the forevacuum line. To supply the
inert purge gas (e. g. nitrogen) to the pump through
the purge port, connect a gas purge valve between
the pressure regulator and the pump.
Adjust the pressure regulator in order to read a gas
flow rate of 0.1 to 0.8 mbar l/s.
A special kit is available to purge this pump.
Please contact Varian for informations.
! ! ! !
To prevent bearing damage, Varian suggests a
minimum purge gas flow rate of 10 sccm (0.17
mbar l/s). This value can be exceeded, according
to the process requirements. Please contact Var-
ian for specific applications.
The purge gas throughput with the recommended
3
forepump of 15 m
high vacuum pressure in the 10
The recommended gas flow maintains a pressure into
the pump body higher than the forevacuum pressure.
The recommended procedure to vent the system
and the pump avoiding the contact between the
pump bearings and the corrosive gas is described
in the following points:
1.
Close the corrosive gas flow into the system.
2.
Leaving the Turbo-V pump and the backing
pump running and the purge gas flowing, wait
for enough time to evacuate the corrosive gas
from the system.
3.
Open the Turbo-V vent port slowly until to
reach atmospheric pressure in the system.
4.
Turn off the Turbopump.
5.
When the Turbo-V pump and the backing
pump are stopped and the system is at at-
mospheric pressure, for a better bearing pro-
tection it is advisable to leave the purge gas
flowing into the Turbo-V pump, with the
chamber or the Turbo-V vent valve opened, to
avoid system overpressures. If the vent valve
can't be kept opened, the backing pump
should be left operating.
1. Purge gas line
2. Pressure regulator
3. Gas purge valve
4. Gas purge kit
5. Forevacuum pump
6. Turbopump
7. Vent valve
35
TECHNICAL INFORMATION
CAUTION
/h (11 CFM) allows to achieve a
-8
mbar range.
Purge layout
87-900-881-01(B)
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