Connection B - Fore-Vacuum Pump; Connection C - Electrical; Pump Used With Corrosive Gases - Varian 969-9369 Manual De Instrucciones

Connection B - FORE-VACUUM PUMP

A flange KF 10 NW is available to connect the Tur-
bopump to the fore-vacuum pump. A hose or vac-
uum 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 bel-
lows.
NOTE
The Turbo pump is characterised by its high com-
pression ratio also for oil vapours. 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.

Connection C - ELECTRICAL

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 20° C) and pin E is connected
to the pump ground.
If the temperature sensor is disconnected, the
pump will not start. To prevent damage to the
pump when the temperature exceeds 60° 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 (see the fol-
lowing figure). Adjust the pressure regulator in or-
der to obtain the necessary gas purge flow rate
according to the application.
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34
TECHNICAL INFORMATION
! ! ! !
CAUTION
To prevent bearing damage, Varian suggests the
following purge gas flow rates: 10 sccm (0.17 mbar
l/s) for a mild purge process, or 15 psig (1 bar l/s)
for an heavy process. Please contact Varian for
specific applications.
The purge gas throughput with the recommended
3
forepump of 2 m /h (1.4 CFM) allows to achieve a
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 port
5. Forevacuum pump
6. Turbopump
7. Vent valve
-8
mbar range.
87-900-891-01(C)