Operation
17
6.3
Pumping condensable vapours
Should the process gases contain condensable gases, the rotary vane pump must be
operated with gas ballast (i.e. with an open gas ballast valve).
Gas ballast valve,
standard version
To avoid condensation in the pump when pumping condensable vapours, air is periodi-
cally fed into the working chamber at the beginning of the compression phase via the gas
ballast valve 115.
The gas ballast valve is closed when turning to the right to position 0 and open when turn-
ing to the left to position 1. Intermediate settings are not possible.
The gas ballast filter is used to keep the air free of particles before entering the suction
chamber.
Fig. 10: Standard version of gas ballast valve 115
Gas ballast valve with
flushing gas connec-
tion (option)
If the pumping process requires the use of flushing gas, a supply hose can be connected
at the gas ballast valve.
Unscrew gas ballast filter 122 at ball valve 120.
On the inside thread G 1/ 2 " of ball valve 120, connect the supply line and seal up
thread side.
Set flushing gas pressure on site; maximum pressure 1500 hPa (absolute).
– Select the type and amount of flushing gas depending on the process; consult Pfei-
ffer Vacuum if necessary.
Dose flushing gas with the knob on the ball valve 120 or with a flow meter on site.
NOTICE
Bad final vacuum and damage to the pump!
Danger of condensation and corrosion due to exceeding the water vapour compatibility
during operation without gas ballast or in case of insufficient supply of flushing gas.
Only pump vapours when the pump is warm and the gas ballast valve is open.
When the process has been completed, allow the pump to continue running for
about 30 minutes with the vacuum flange closed and the gas ballast open for oper-
ating fluid regeneration purposes.
115 Gas ballast valve (ball valve)
122 Gas ballast filter
"I"
"0"
122
115
120
