© Edwards Limited 2008. All rights reserved.
Page 15
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Installation
B777-00-880 Issue E
If you use a TAV vent valve or other solenoid vent valve, you should only use the vent valve to vent the pump from
full speed if the vacuum system has a volume of 20 litres or more. If the system has a volume of less than 20 litres
you should incorporate a suitable restrictor (see below and
). Alternatively, if you are using an EXC controller
to operate the vent valve, you can configure the valve so that it opens once the pump has reached 50% of full
rotational speed.
Do not vent from the backing line as this may lead to contamination. If you vent into your vacuum system, select a
point upstream of the pump to prevent oil backstreaming from the backing line.
If you use the TAV5 or TAV6 vent valve you can control it using an EXC controller or by other methods.
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
.
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
) in place of the blank plug
(item 6,
). Connect your gas supply to the purge port. Your purge gas must comply with the specification
given in
.
You must limit the purge gas flow rate to the allowed range, also specified in
. To limit the flow rate use
a flow controller or a pressure regulator and calibrated flow restrictor. The PRX10 purge restrictor accessory
(see
) 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,
) 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.
Table 7 - Vent restrictor orifice diameter (with atmospheric pressure at the inlet)
Vacuum system volume (litres)
Orifice diameter (mm)
< 20
< 1.0
< 10
< 0.7
< 5
< 0.5
< 2
< 0.35
