Description
11GA01601_002_C1 - 03/2018 - © Leybold
By opening the gas ballast valve (2/1, optional) it is possible to admit a
controlled quantity of air (gas ballast) into the pump chamber while the com-
pression process is in progress. The gas ballast will prevent the condensation
of vapours within the pump up to the extent of the vapour tolerance levels as
stated in the specifications for the pump (these data refer to water vapour).
A special lubrication system with forced lubrication of the sliding bearings has
been developed to enable operation of the pump at intake pressures up to
1000 mbar.
An oil pump supplies the oil from the oil reservoir into a high pressure oil sys-
tem which in turn supplies all bearings. From here the oil enters the pump
chamber of the vacuum pump. The oil pump is located in bearing piece of
the high vacuum stage. Separation of oil and gas in the pump involves two
stages. First an internal demister which is arranged ahead of the exhaust
valve ensures the creation of larger droplets.
Next these are returned back to the oil reservoir via a separation panel. This
ensures a minimal loss of oil.
This and the combination with the large usable oil reservoir, results in long
intervals between the oil exchanges, even at high intake pressures.
When the pump is at standstill (mains power failure, or when the pump is
shut down) the pump chamber is hermetically sealed off by a safety valve
(tandem valve) which is controlled through the oil pressure.This requires that
the gas ballast solenoid valve be closed.
This reliably avoids any inadvertent venting of the vacuum chamber and the
backstreaming of oil.
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