Ulvac MS120A, Instruction Manual

Page: 41 / 69

27
YO20-0938-DI-001-00
3.5.4 Purge Gas
This machine has a purge gas introduction mechanism.
If the target gas contains condensable gas and moisture, liquid may collect in the final stage of the pump.
Therefore, use purge gas to prevent the gas from liquefying and accumulating inside the pump body. In
addition, for explosive/flammable/combustion-supporting gas, dilute it with purge gas to the extent that the
danger is eliminated. Introduce purge gas to reduce the accumulation of corrosive/reactive products when
pumping such a gases.
As the purge gas, introduce nitrogen or CDA (dew point: -60°C). Decide which one to use as the purge gas
depending on the process. (CDA cannot be used for dangerous processes that react with oxygen). Adjust
the flow rate after starting the pump.
Use the included nuts and ferrules.
Use the included nuts and ferrules for installing piping. Using parts other than
those specified may cause a malfunction or accident.
Perform warm-up operation before processing and degassing
operation when the unit is stopped.
When processing, be sure to perform warm-up operation before processing
and degassing operation when the unit is stopped each for one hour
(operation in the atmosphere relief mode). In the event of processing under
the condition where the increase in temperature of the pump in early stages
is insufficient or in the presence of residual gas when the pump stops,
condensable gas condenses inside the pump, which may shorten the life of
the pump.
The configuration is such that the condensed gas does not return
directly to the pump.
For the configuration, bend sideways the piping on the exhaust side using an
L-shaped pipe or by other means so that the condensed gas does not return
directly to the pump. It is recommended to provide a mechanism to drain
accumulated liquid.
Reference of water vapor tolerance is 1.5kg/hr.
If water vapor exceeding the processing capacity, it may condense inside the
pump even if purge gas is used, shortening the life of the unit. In addition, it
is recommended not to stop the unit without intermittent operation.
Connect the purge gas piping according to the following specifications:
NOTES
NOTES
NOTES