Edwards, nEXT Turbomolecular Pumps, nEXT240, nEXT300 and ...

B800-00-880 Issue B
3.3.6 Interstage connection (variants only)
Use suitable vacuum tube and connectors to connect the interstage-port to your vacuum system or to the outlet
flange of another turbo or compound turbomolecular pump (if using an “i” nEXT pump to back another pump). Leave
the inlet-strainer in the interstage-port, unless you are sure that debris cannot be drawn into the interstage-port.
3.4 Purge gas connection
Installation
3.4.1 Connect the purge gas
To supply a purge gas to the pump, remove the plug fitted in the purge-port, fit a vent-port adaptor (refer to
Section 7.4) and connect the purge gas supply to the vent-port adaptor. The purge gas must comply with the
specification given in Section 2.4.
3.4.2 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 pumping oxygen in concentrations above 20% by volume.
The flow rate of the purge gas must be limited to the allowed range, specified in Section 2.4. To limit the flow rate,
use a flow controller or a pressure regulator and calibrated flow restrictor. The PRX10 purge restrictor accessory
(refer to Section 7.4) is suitable for this purpose.
3.5 Electrical installation
3.5.1 Introduction
The electrical installation must be carried out by a suitably-qualified person. Always make the electrical connections
to the nEXT pump after the pump has been installed on your vacuum system. Always disconnect all electrical
connections from the nEXT pump before removing it from the vacuum system.
Earth the pump using the connection provided and refer to Section 3.5.2.
You can operate the nEXT pump using the Edwards TIC Turbo Instrument Controller or TIC Turbo Controller, refer to
Section 3.5.3. You can also control the nEXT pump using your own system, refer to Section 3.5.4 for information
about control and to Section 3.5.5 for instructions on how to connect your electrical supply.
3.5.2 Earth (ground) connections
WARNING
You must make sure that the pump is electrically bonded to earth. If you do not, the system could
become hazardous live in the event of a live conductor touching a metallic surface.
We recommend that you fit a separate earth (ground) conductor to earth the nEXT pump. Use an un-insulated braid
or a separate insulated green/yellow conductor with a minimum 10AWG (5.3mm 2 ) conductor to comply with US and
Canadian installation codes, and use the M5 x 10 screw and shake proof washer supplied (fitted to the earth hole on
the pump) to secure the earth conductor to the pump. The impedance between the pump-body and the earth
connection point must be < 0.1 Ohm.
3.5.3 Connect the logic interface to the TIC
If you are using the Edwards TIC Turbo Instrument Controller or TIC Turbo Controller to power and control your pump,
the nEXT pump logic interface cable connects directly into the back of the TIC. Refer to the TIC Instruction Manual
for further information.
© Edwards Limited 2009. All rights reserved. Page 29
Edwards and the Edwards logo are trademarks of Edwards Limited.