Edwards EXT250 Series, Инструкция по эксплуатации, Страница: 26 / 42

B722-01-880 Issue K
Page 20 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Installation
3.5 Purge gas connection (EXT250 only)
3.5.1 Connect the purge gas
If you want to supply a purge gas to the pump, remove the purge plug from the purge-port, fit a vent port adaptor
(see
Section 7.4.6 ) to the purge-port, then connect your purge gas supply to the vent port adaptor. Your purge gas
must comply with the specification given in Section 2.6 .
You must limit the flow rate of the purge gas to the allowed range, also specified in Section 2.6 . To limit the flow
rate, use a flow controller or a pressure regulator and calibrated flow restrictor.
The PRX10 purge restrictor accessory (see Section 7.4.9 ) is suitable for this purpose. Adjustment of the PRX10 is
described in the instruction manual supplied with the accessory.
3.5.2 Recommended purge gas flow
The recommended purge gas flow for typical applications is 25 sccm (0.42 mbar l s
-1
, 42 Pa l s
-1
). This flow will protect
the pump when you pump oxygen in concentrations above 20% by volume.
3.6 Electrical installation
Always make the electrical connections to the EXT pump after the pump has been installed on your vacuum system.
The EXC Controller provides the electrical supply to the EXT pump through the multiway pump-to-controller cable.
Connect and lock the bayonet-connectors at the ends of the cable to the mating connectors on the pump and the
EXC Controller.
The EXC Controller is designed to allow a pumping system to be configured in a variety of ways, from a basic
manually-operated system to a fully automatic system with remote control. Refer to the instruction manual supplied
with the EXC Controller to complete the electrical installation.
3.7 Cooling
CAUTION
When you bake the EXT pump to above 70
o
C at the inlet-flange, you must cool the pump by forced-air or water-
cooling to prevent damage to the bearing lubricant.
WARNING
You must electrically bond the EXT pump to earth (ground): use the earth (ground) screw provided
on the pump (
Figure 4 , item 2 and Figure 5 , item 3).