Pump Used With Corrosive And Oxidizing Gases - Agilent Technologies TwisTorr 305 FS Notice De Mode D'emploi

Pump Used with Corrosive and Oxidizing 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.
To prevent bearing damage, Agilent suggests a minimum purge gas flow rate of
CAUTION!
10 sccm (0.17 mbar l/s). This value can be exceeded, according to the process
requirements. Please contact Agilent for specific applications.
When a purge gas is used with the recommended forepump of 15 m
(8.82 CFM) a high vacuum pressure in the 10
The recommended gas flow maintains a pressure into the pump body higher than the
fore-vacuum 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
2
3
4
5
TwisTorr 305 FS User Manual / 87-901-057-01 (A.00)

Pump Used with Corrosive and Oxidizing Gases

Close the corrosive gas flow into the system.
Leave the Turbo pump and the backing pump running and the purge gas flowing,
wait for enough time to evacuate the corrosive gas from the system.
Turn off the Turbopump and the backing pump.
Open the Turbo vent port slowly until to reach atmospheric pressure in the system.
When the Turbo pump and the backing pump are stopped and the system is at
atmospheric pressure, for a better bearing protection it is advisable to leave the
purge gas flowing into the Turbo pump, with the chamber or the Turbo vent valve
open, to avoid system overpressures. If the vent valve can't be kept open, the
backing pump should be left operating.
Technical Information
mbar range can be achieved.
-8
8
/h
3
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