5.2.2 Mode selector
Note:
The pump is supplied with High Vacuum mode selected. If High Vacuum mode
S
is
selected and the mode selector cannot be turned by hand to select the High Throughput
mode, use a suitable tool fitted to the flat part of the mode selector to turn the selector.
The mode selector controls the flow of pressurised oil to the high vacuum stage of the
pump (see
on page 11). The can be turned to one of two positions, as
follows:
To select the High Vacuum mode
S
, turn the mode selector fully clockwise and tighten
by hand. When High Vacuum mode is selected, there is a gap of approximately 3 mm
between the mode selector and the inner face of the side panel of the pump. Use this
mode:
▪
to achieve ultimate vacuum
▪
to pump clean gases
▪
to pump clean condensable vapours.
To select the High Throughput mode
S
, turn the mode selector fully anticlockwise until it
touches the inner face of the side panel of the pump, then gently tighten by hand. Use
this mode:
▪
for long-term operation with high gas throughput (that is, inlet pressure >
50 mbar)
▪
to pump dirty condensable vapours
▪
to decontaminate the oil.
5.2.3 Gas-ballast control
Use the gas-ballast control to change the amount of air (or inert gas) introduced into the
low vacuum stage of the pump (refer to
on page 12). Use of gas-
ballast will prevent the condensation of vapours in the pump. The condensates would
contaminate the oil. The gas-ballast control can be turned to select one of three
positions, as follows:
To select gas-ballast closed, turn the control to position ‘0’. Use this setting:
▪
to achieve ultimate vacuum
▪
to pump dry gases.
To select low flow gas-ballast, turn the control to position ‘I’. Use this setting:
▪
to pump low concentrations of condensable vapours
▪
to decontaminate the oil.
To select high flow gas-ballast, turn the control to position ‘II’. Use this setting:
▪
to pump high concentrations of condensable vapours.
When using either low flow or high flow gas-ballast, there will be an increased rate of oil
loss from the pump. Where possible, we recommend that low flow gas-ballast (position
‘I’) is selected, rather than high flow gas-ballast (position ‘II’), to minimise the loss of oil.
03/2021 - ©Edwards Limited
Page 36
A65201880_AA
A65201880_AA - Operation