Edwards XDS46i

5. Operaon
5.1 Use of gas ballast control (if ed)
The gas ballast control can be used to opmise the performance of the scroll pump for
the applicaon. The performance characteriscs of the pump with the dierent ballast
sengs are shown in Table: Performance characteriscs on page 12. The posion of the
gas ballast control can be changed when the pump is o or operang.
5.1.1 Gas ballast control
Use the gas ballast control to change the amount of air introduced into the nal stage of
the pump. Use of gas ballast will reduce the condensaon of vapours in the pump, the
condensates would contaminate the pump. The gas ballast control can be set to select
one of three opons:
To select no gas ballast, turn the control posion to '0'. Use this seng:
▪ to achieve ulmate vacuum
▪ to pump dry gases.
To select low ow gas ballast, turn the control to posion 'I'. Use this seng:
▪
to pump low concentraons of condensable vapours
▪
to decontaminate the pump.
To select high ow gas ballast, turn the control to posion 'II'. Use this seng:
▪ to pump high concentraons of condensable vapours
▪ to clear excess vapours aer processing.
High ow gas ballast 'II' is not intended for long term use as p seal wear is accelerated.
For connuous operaon, to dilute condensable vapours for example, gas ballast
posion '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 ne dust may be emied from the exhaust of the scroll pump during start up,
parcularly when the pump is new or if new p seals are ed.
Use the procedure below to start up the pump:
1.
Ensure that any vacuum system isolaon valve is closed (if ed).
2.
Connect a suitable lead from the power supply to the appliance inlet at the side of
the pump.
Page 21
A73101880_F - Operaon