B722-40-880 Issue H
Page 20
© Edwards Limited 2018. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Installation
The inlet connections for the EXT75DX are CF flange, ISO flanges and the NW flange:
If the pump has a CF flange, use the copper compression gasket supplied with the pump and use a full
complement of bolts to connect the inlet flange of the pump to the vacuum system.
If the pump has an ISO flange, use the Edwards trapped O-ring supplied with the pump and use a minimum of
four claw clamps (each torqued to 10 Nm) to connect the inlet flange of the pump to the vacuum system.
Alternatively, use a rotatable collar and the trapped O-ring supplied with the pump to connect the inlet
flange of the pump to the vacuum system; use a full complement of bolts with the rotatable collar.
If the pump has an NW flange, use the centring ring supplied with the pump and a metal NW clamp to
connect the inlet flange of the pump to the vacuum system. In this case, fix the base of the pump to a firm
support as described in
All inlet flange bolts must be re-tightened once the system is under vacuum. Ensure that no torques or other forces
are transmitted to the pump from the vacuum system or the associated pipelines. If necessary, fit an inlet vibration
isolator between the pump inlet and the vacuum system (refer to
). In this case, fix the base of the pump
to a firm support as described in
.
3.3.4
Base mounting
The base of the DX pump can be fixed to a firm support using the tapped fixing holes. Refer to
for fixing hole
details.
Note:
For EXT75DX only, the four screw-in rubber feet must be removed from the four tapped fixing holes before
the pump can be base mounted.
Edwards recommends that the following requirements be met to ensure the pump remains secure in the event of a
total pump seizure:
Use this method of fixing the pump if it supports the weight of the vacuum system. The weight of the vacuum system
must be no more than 10 kg for EXT75DX.
3.3.5
Backing connection
CAUTION
Do not use the DX pumps with a backing pressure below 5 x 10
-4
mbar (5 x 10
-2
Pa). Lower backing pressures
will increase the evaporation rate of the lubricating oil and so may reduce the life of the bearings.
Support must withstand a destructive torque of:
333 Nm (EXT75DX)
Fixing screws:
To ISO898-1 strength class 12.9
(nom. tensile strength 1200 MPa)
Screw engagement length:
6 mm minimum
Fastening torque:
6 Nm (0.61 kgf.m) (EXT75DX)
WARNING
Ensure safe ducting of the backing line if oil mist or hazardous substances are present.
WARNING
To avoid over-pressurising the pump, the exhaust line should be restricted when venting from a
positive pressure gas supply.
