WARNING: EJECTION OF PARTS
If the mounting is not sturdy enough, pump blockage could cause the pump to break
loose; internal pump components could be thrown in all directions.
Mount the pump firmly to the vacuum chamber. Never operate the pump without
proper flanging to the vacuum chamber (in bench testing, for example). In case of
rotor destruction a sudden twisting of the entire pump is possible. The vacuum
chamber must be able to absorb the torque of max. 5 kNm for the nEXT730/930 and
of max. 9 kNm for the nEXT1230 around the rotor's axis of rotation in the event of
sudden rotor destruction.
If a pump fails it is likely to eject parts into the vacuum system onto which it is
mounted. The customer must ensure that a hazard is not created should this occur.
5.2.3 Mount the pump
Make sure that the pump inlet and all components fitted to the pump inlet are clean and
dust- free. If the pump inlet is not kept clean, the pump-down time may be increased.
▪ The inlet connections for the nEXT pumps are either ISO flange or CF 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. Screws with a minimum Grade 8.8 or A2(A4)-70 are necessary.
Lubricate and tighten the screws stepwise to a torque of 15
+2
Nm. Refer to Figure:
Mounting high vacuum CF flange connection with blind hole thread.
▪ If the pump has an ISO-K flange, use the Edwards combination inlet screen/trapped
O- ring supplied with the pump and use a minimum of
▪ 12 clamps for the nEXT730/930 with a minimum yield strength of 380 N/
mm
2
. Tighten the claw clamps with a torque of 20
+3
Nm. Refer to Figure:
Mounting high vacuum flange ISO-K flange at ISO-K flange.
▪ 18 clamps for the nEXT1230 with a minimum yield strength of 500 N/mm
2
.
Tighten the claw clamps with a torque of 27
+3
Nm. Refer to Figure: Mounting
high vacuum flange ISO-K flange at ISO-K flange.
▪ 12 claws for the nEXT730/930 with bolts of a minimum ISO class 8.8. Tighten
the screws stepwise to a torque of 35
+5
Nm. Refer to Figure: Mounting high
vacuum flange ISO-K flange at ISO-F flange with claws
▪ Mounting of the nEXT1230 with claws is not allowed.
▪ 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 minimum ISO class 8.8 bolts. Tighten the bolts
stepwise to a torque of 35
+5
Nm. Refer to Figure: Mounting high vacuum flange
ISO-K flange at ISO-F flange with collar flange.
▪ If the pump has an ISO-F flange, use the Edwards inlet screen supplied with the
pump, a centering ring with O-ring and use a minimum of 12 bolts M10 (Bolt
quality: 8.8 according to EN ISO 898-1 with coating, each torqued to 35
+5
Nm) to
connect the inlet flange of the pump to the vacuum system. Refer to Figure:
Mounting high vacuum ISO-F flange connection with blind hole thread.
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