Gas Ballast Function - Ulvac VD30C Instruction Manual

4. 4 Gas Ballast Function

This product is installed with the gas ballast function as standard. When using the gas ballast
function depending on the application, the needle valve, the pipe and the like are connected to gas
ballast port (G3/8).It is applicable to breathe in the condensed gas such as the steam and solution
vapor.
Breathed condensed gas shall be liquefied through the compress process of the Pump, mixed
with the Pump oil and then cycled mixed together inside the Pump unit. This status brings you the
same situation that you used the high steam pressure oil that raises the ultimate pressure. It also
shortens the life cycle of the Shaft seal since the oil lubrication shall deteriorate.
If introduced the air or dry nitrogen through the gas ballast valve just before the Pump
compression process, the condensed gas is not liquefied but exhausted with the air through the
Exhaust valve.
To use the gas ballast, breathe in the air through the gas ballast valve before sucking in the
condensed gas and operate the Pump around twenty minutes; this is because the "gas ballast
effect" becomes larger as the Pump temperature is higher. Wait until the Pump temperature raises
enough to open the main valve (Fig. 15) So as to operate the Pump. The "gas ballast effect" under
low temperature shall be lower than the specified process performance.
Note further that keeping the gas ballast valve open when not breathing in the condensed gas
shall cause the Pump oil splashing and power loss and further rise the ultimate pressure. You have
to note also that the condensed gas might remain in the Pump oil after you have exhausted a lot
of condensed gas or exhausted the condensed gas (air or gas that contains less water or other
steam that contaminates the oil) without opening the gas ballast valve since the process capacity
of the condensed gas by the gas ballast valve is limited.
In such a case, close the Main valve, breathe in the air through the gas ballast valve and idle
operate the Pump. Then the oil temperature shall rise up and be cleaned by means of the Gas
ballast effect. Keep on idle operating the Pump without opening the gas ballast valve as far as the
specified ultimate pressure is attained. You need to replace the Pump oil if it was not cleaned after
operated long time.
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②
WARNING
If you kept opening the gas ballast valve when not exhausting the condensed
gas, it might cause the oil splash, power loss or ultimate pressure rise.
Keep the gas ballast valve closed when not exhausting the condensed gas.
CAUTION
The Vacuum pump gets high temperature during operation. As the gas
ballast valve also gets high temperature, be sure to wear protective gear
such as a pair of gloves.
Ensure to close the gas ballast valve to start operating the Pump.
The oil might jet out of the gas ballast valve during the operation around high
pressure range.
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YK15-0009-DI-002-04