BOC Edwards EXT555H, Instruction Manual

Page: 21 / 44

Jun 01 Issue A
EXT555H
IN
STALL
A
TION
PAGE
15
15
If you use the TAV5 or TAV6 vent valve you can
control it using an EXC controller or by other
methods. Table 7 gives an indication of the
appropriate size of orifice to be fitted to the vent
valve for given vacuum system volumes in order that
the vent rate is kept within the limits given in
Figure 3.
Refer to Section 2 for information on vent gas
specification.
3.5 Purge gas connection
3.5.1 Connect the purge gas
If you want to supply a purge gas to the pump, fit a
vent port adapter (see Section 7) in place of the
blank plug (item 6, Figure 4). Connect your gas
supply to the purge port. Your purge gas must
comply with the specification given in Section 2.
You must limit the purge gas flow rate to the
allowed range, also specified in Section 2. 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) is suitable
for this purpose. Adjust the PRX10 as 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
Note: You must electrically bond the EXT555H
pump to earth (ground) using the earth
(ground) screw provided on the pump (item 5,
Figure 4) to ensure that the pump complies
with EN61010.
Always make the electrical connections to the pump
after the pump has been installed on the vacuum
system.
The EXC controller provides the electrical supply to
the EXT555H pump through the 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 (if
applicable). If the cable is disconnected at either end
while the pump is operating, the EXC controller
output is switched off, which makes the cable safe.
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 controller to
complete the electrical installation.
3.7 Cooling
3.7.1 Introduction
You must use water cooling in any of the following
operating conditions:
• When backing pressure is high (see Table 5).
• When you bake the EXT pump or the vacuum
system close to the pump.
• When the ambient temperature is above
35 °C.
• When there is high continuous gas
throughput (see Table 5).
In all other operating conditions, you can use forced
air cooling. If you use forced air cooling you must
ensure that there is an adequate supply of cooling air
to the pump.
CAUTION
You must cool the pump by forced-air or water
cooling to prevent damage to the bearing.