4-22 Maintenance Procedures
Gas ballasting the roughing pump
Note: This procedure is not required for an oil-free roughing pump.
Roughing pump:
The roughing pump draws large quantities of solvent vapors. The vapors tend
to condense in the pump oil, diminishing pumping efficiency. Gas ballasting
purges condensed contaminants from the oil.
Gas ballast the roughing pump when these conditions apply:
• With ESI operation, once a week.
• When the roughing pump oil appears cloudy.
• When the vacuum pressure is higher than normal.
• When condensate forms in the roughing pump exhaust line.
• When you change the roughing pump oil.
The roughing pump can be fitted with either of the following:
Caution: Failure to routinely gas ballast the roughing pump shortens oil
life and, consequently, pump life.
Oil filler plug
Oil-level sight glass
Drain plug
Gas ballast valve
Exhaust port flange
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