© Edwards Limited 2013. All rights reserved.
Page 33
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Installation
B800-00-880 Issue D
Use suitable vacuum tubing and connectors to connect the NW flange of the backing port to the backing pump. If
necessary, use flexible pipe or bellows to reduce the transmission of vibration from the backing pump to the nEXT
pump.
Edwards recommends using an Edwards EM, RV or XDS Scroll backing pump. The recommended size of backing pump
required is indicated in
Table 6
. A larger or smaller backing pump may also be suitable, depending upon the
application it is intended for.
The nEXT pumps are suitable for use with diaphragm backing pumps although the effect of higher backing pressure
on the pump's performance and cooling requirements should be noted. Refer to
Table 6
and
Section 2.1
.
3.3.6
Interstage connection (variants only)
Use suitable vacuum tube and connectors to connect the interstage port to the 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 it is certain that debris cannot be drawn into the interstage port.
3.4
Purge gas connection
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 qualified person. Always make the electrical connections to the
nEXT pump after the pump has been installed on the 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
.
The nEXT pump can be operated using the Edwards TIC Turbo Instrument Controller or TIC Turbo Controller (refer to
Section 3.5.3
). The nEXT pump can also be controlled using the customer system. Refer to
Section 3.5.4
for
information about control and to
Section 3.5.5
for instructions on how to connect the electrical supply.
WARNING
Ensure the electrical installation of the nEXT pump conforms with local and national safety
requirements. It must be connected to a suitably fused and protected electrical supply with a
suitable earth (ground) point.
