18
Operation
6.5 Operation with gas ballast valve
Steam or moisture from pumped media can condense in the vacuum pump and
hence impair the suction performance.
Letting in gas ballast improves the discharge of condensate, and the pump
achieves the specified final vacuum more quickly. The gas ballast valve can be re-
placed with a flushing gas connection if necessary.
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For operation with gas ballast, please refer to the operating manual for the ba-
cking pump.
6.6 Operation with fore-vacuum valve
The fore-vacuum safety valve (optional accessory) is located in the fore-vacuum
line between the turbopump and the backing pump. It protects the process vacuum
and the turbopump from inadvertent venting upon stillstand of the pumping sta-
tion (backing pump) or power failure. The valve is closed currentless.
• Pumping station "On" = Fore-vacuum safety valve open
• Pumping station "Off" = Fore-vacuum safety valve closed
6.7 Switching off and venting
Switching off
After the turbopump is switched off, it must be vented to avoid contamination due
to particles streaming back from the fore-vacuum area.
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Switch off the pumping station via the "ON/OFF" button on the DCU.
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Venting (possibilities, see below)
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Switch off the pumping station at the master switch.
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For water cooling: Shut off the water supply.
Venting
Venting with Pfeiffer Vacuum Venting Valve
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Enable venting via the functions of the electronic drive unit.
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Settings are possible via the RS485 by using DCU, HPU or PC.
1)
When mains power is restored the venting procedure is aborted.
Basic information for the rapid venting
Venting of the vacuum chamber in two steps. Ask for details on individual solutions
from Pfeiffer Vacuum.
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Vent for 20 seconds at a rate of pressure rise of max. 15 mbar/s.
– The valve cross section for the venting rate of 15 mbar/s must be adapted to
the size of the vacuum chamber.
– For small vacuum chambers, use the Pfeiffer Vacuum venting valve.
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Then vent with an additional venting valve of any desired size.
WARNING
Risk of electric shock
The pumping station is only free of voltages when the mains plug has been disconnec-
ted.
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Switch off the master switch and disconnect the mains plug before all work.
Venting rotation speed
Switch off the pumping station Mains power failure
1)
50% of the nominal rotation
speed
Venting valve opens for 3600 s (1 h,
works setting)
Venting valve opens for
3600 s (1 h, works setting)
