Edwards EXT250 Series, Instruction Manual, Page: 29 / 42

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Operation
B722-01-880 Issue K
4 Operation
4.1 Start-up
Use the procedure below to start up a basic, manually-controlled pumping system with a manual vent-valve and an
EXC Controller. Refer to the EXC Controller instruction manual where the backing-pump and accessories are
automatically controlled by the EXC Controller.
1. Turn the manual vent-valve clockwise to close it.
2. Turn on the cooling-water supply (if water-cooling is used).
3. Start the backing-pump.
4. When the vacuum system pressure is approximately 1 mbar (1 x 10
2
Pa) or less, press the Start/Stop button on
the EXC Controller to start the EXT pump.
5. The pump will then accelerate to full operating speed. When this has been reached, the upper LED of the speed
indicator on the front panel of the EXC Controller will light.
Note: The first time you pump down the system to vacuum, you must re-tighten the bolts which secure the inlet-
flange: refer to
Section 3.3.4 .
4.2 Stand-by
You can press the Standby button on the EXC Controller to operate the EXT pump at reduced rotational speed. Select
Standby before or after Start-up, for any of the following reasons:
z
To extend pump-bearing life and still maintain adequate vacuum pumping performance (for example, when
you leave a system under vacuum over holiday periods)
z
To increase system pressure or to extend the maximum inlet pressure range of the pump where this suits a
particular process
z
To avoid pump excitation of any resonances which may exist on sensitive instrumentation.
WARNING
Do not disconnect the pump-to-controller cable when the EXT pump is operating. If you do, there
may be a risk of injury or death by electric shock.
WARNING
Do not expose any part of your body to vacuum. If you do, you may be injured.