B800-00-880 Issue D
Page 32
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Installation
The inlet connections for the nEXT pump are CF flange, ISO flange and VG 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 combination inlet screen/trapped O-ring supplied with the
pump and use a minimum of four claw clamps (each torqued to 30 Nm) to connect the inlet flange of the
pump to the vacuum system. Alternatively, use a rotatable collar and the combined inlet screen and 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 a VG flange, use a full complement of 8x M10 bolts and washers to connect the pump to the
vacuum system. Flange fixings bolts must be a minimum of 700 MPa tensile strength and evenly tightened in
a cross pattern in 3 tightening stages to a final torque of 30 Nm to ensure even compression of the O-ring and
clamping of the flanges.
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
damper between the pump inlet and the vacuum system. In this case, fix the base of the pump to a firm support, as
described in
Section 3.3.4
.
3.3.4
Base mounting
The base of the nEXT pump can be fixed to a firm support using the tapped fixing holes. Refer to
Figure 4, 5 and 6
for fixing hole details.
Note:
The four rubber feet must be removed from the four tapped fixing holes before the pump can be base
mounted.
The following requirements should be met to ensure the pump remains secure in the event of a total pump seizure:
This method of fixing must be used if the pump supports the weight of the vacuum system. The weight of the vacuum
system must be no more than 20 kg.
3.3.5
Backing connection
CAUTION
Do not use the nEXT 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:
6 KNm
Fixing screws:
4 off M8 to ISO898-1 strength class 12.9
(nom. tensile strength 1200 MPa)
Screw engagement length:
6 mm minimum
Fastening torque:
15 Nm (1.53 kgf.m)
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 not be restricted when venting from
a positive pressure gas supply.
