Operation; Use Of Gas Ballast Control (If Fitted); Gas Ballast Control; Start Up Procedure - Edwards XDS35iC Instruction Manual

5. Operation

5.1 Use of gas ballast control (if fitted)

The gas ballast control can be used to optimise the performance of the scroll pump for
the application. The performance characteristics of the pump with the different ballast
settings are shown in
control can be changed when the pump is off or operating.

5.1.1 Gas ballast control

Use the gas ballast control to change the amount of air introduced into the final stage of
the pump. Use of gas ballast will reduce the condensation of vapours in the pump, the
condensates would contaminate the pump. The gas ballast control can be set to select
one of three options:
To select no gas ballast, turn the control position to '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 pump.
To select high flow gas ballast, turn the control to position 'II'. Use this setting:
▪ to pump high concentrations of condensable vapours
▪ to clear excess vapours after processing.
High flow gas ballast 'II' is not intended for long term use as tip seal wear is accelerated.
For continuous operation, to dilute condensable vapours for example, gas ballast
position 'I' is recommended.

5.2 Start up procedure

WARNING:
Ensure that the system design does not allow the exhaust pipeline to become
blocked.
CAUTION:
A fine dust may be emitted from the exhaust of the scroll pump during start up,
particularly when the pump is new or if new tip seals are fitted.
Use the procedure below to start up the pump:
1. Ensure that any vacuum system isolation valve is closed (if fitted).
2. Connect a suitable lead from the power supply to the appliance inlet at the side of
the pump.
A73001880_N
A73001880_N - Operation
Table: Performance characteristics. The position of the gas ballast
Page 23 11/2020 - ©Edwards Limited