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Gas Ballasting and Rotary Pump Oil Recirculation
Gas ballasting serves two important
purposes:
•
When rotary pumps are used
to pump away solvent
vapours, the solvent vapour
can become dissolved in the
pump oil causing an increase
in backing line pressure. Gas
ballasting is a method of
purging the oil to remove
dissolved contaminants.
•
Oil mist expelled from the
rotary pump exhaust is
trapped in the oil mist filter.
This oil is returned to the rotary pump during gas ballasting.
The Quattro Ultima has two rotary pumps; an E1M18 pumping the source block and
an E2M28 pumping the first hexapole. Because the source block is maintained at a
relatively high pressure, the rate of oil mist being expelled from the E1M18 pump is
considerably higher than that from the E2M28 pump. Consequently, it is
recommended that the E1M18 pump is operated continuously in gas ballast mode so
that the pump oil is continuously recirculated.
Continual operation in gas ballast mode is not usually recommended as venting
of the instrument whilst rotary pumps are ballasting can cause oil vapour to
migrate into the vacuum housing. However, the E1M18 has an additional
automatic gas ballast control valve mounted in the oil return line from the mist
filter. This valve is opened whenever the E1M18 is switched on, allowing
continuous recirculation of the pump oil provided that the manual gas ballast
valve on the pump is left open.
In the event of a vent command or automatic vent (vacuum fault or power
failure) the pump is switched off and the automatic gas ballast valve closes thus
preventing any contamination of the vacuum housing.
The E2M28 rotary pump is not equipped with an automatic gas ballast control valve,
and this pump should normally be operated with the manual gas ballast valve closed.
The valve should only be opened for 30 minutes each week to perform routine gas
ballasting of the pump. If the source is used in the APcI or megaflow electrospray
modes, more frequent gas ballasting is recommended.
The manual gas ballast valve is opened by rotating it fully counterclockwise.
It is normal for the rotary pump to make more noise when the gas ballast valve
is open.
Maintenance and Fault Finding
Page 180
Quattro Ultima
User's Guide
Gas
Ballast
Drain
Plug
Exhaust
Filler
Plug
Oil Level
Indicator
Oil Mist
Filter
Summary of Contents for Quattro Ultima
Page 2: ...Quattro Ultima User s Guide...
Page 68: ......
Page 100: ...Data Acquisition Page 100 Quattro Ultima User s Guide...
Page 117: ...Mass Calibration Page 117 Quattro Ultima User s Guide...
Page 140: ...Mass Calibration Page 140 Quattro Ultima User s Guide...
Page 212: ...Maintenance and Fault Finding Page 212 Quattro Ultima User s Guide...
Page 222: ...Reference Information Page 222 Quattro Ultima User s Guide...