To Achieve Ultimate Vacuum (If Gas Ballast Fitted); To Pump Condensable Vapours (If Gas Ballast Fitted); Implication Of Atex Directive; Flammable/Pyrophoric Materials - Edwards XDS35iC Instruction Manual

3. Switch on the electrical supply to the pump, using the Run/Standby switch
General
4. With manual operation always use the Run/Standby switch to start/stop the pump.
If remote operation is used to control the pump, refer to
15-way D connector
5. Open the vacuum system isolation valve (if fitted).

5.3 To achieve ultimate vacuum (if gas ballast fitted)

In order to achieve the best possible vacuum, the pump should be operated with the gas
ballast control on position '0'. However, if the pump, or elements of the vacuum system
it is attached to, are new or have been newly fitted, some atmospheric moisture may be
present. If atmospheric moisture is present, run the pump with the gas ballast control in
position 'I' or 'II' for 20 minutes before switching to position '0'. If moisture is allowed to
remain, the performance of the pump will be impaired.

5.4 To pump condensable vapours (if gas ballast fitted)

Select a suitable gas ballast setting (gas ballast control in position 'I' or 'II') when there is
a high proportion of condensable vapours in the process gases. This will assist the
vapours to pass through the pump without condensing and keep the pump performance
from degrading.

5.5 Implication of ATEX directive

5.5.1 Flammable/pyrophoric materials

When flammable or pyrophoric materials are present within the equipment:
▪ Do not allow air to enter the equipment.
▪ Ensure the system is leak tight.
▪ Dilute any flammable gases or vapours by using an inert purge, for example
nitrogen, to the pump inlet and gas ballast (if fitted) to reduce the concentration of
flammable gases or vapours in the pump and exhaust line to less than one quarter
of the published Lower Explosive Limits (LEL).
▪ Prevent the condensation of flammable vapours within the pump mechanism and
exhaust line by using an inert gas purge to the pump gas ballast connection. Note
that this option is not available on the No Gas Ballast versions. In these pumps only
inlet purge can be used.

5.5.2 Gas purges

WARNING:
If nitrogen purges are used to dilute dangerous gases to safe levels, ensure that the
system shuts down if the nitrogen supply to the pump fails.
The following actions must be taken to ensure that the gas being pumped stays out of
the flammable range:
A73001880_N
A73001880_N - Operation
view, item 9.
on page 25.
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Figure:
Remote operation using
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