Waters Xevo TQD Overview And Maintenance Manual page 187

To avoid damage, do not overtighten the nut that secures
Notice:
the oil demister element onto the exhaust flange; ensure that only
approximately 1 mm of thread is exposed beyond the nut when it
is tightened.
3. Use the 10-mm wrench to fit and tighten the nut that secures the oil
demister element to the exhaust flange.
4. Ensure that the inscription "TOP" is at the top of the oil demister
element, and, using both hands, carefully fit the oil demister element
and exhaust flange to the roughing pump.
The bolts securing the source exhaust flange to the
Requirement:
roughing pump must each be sequentially and incrementally tightened
until they are all fully tight.
5. Use the 6-mm Allen wrench to fit the 4 bolts securing the exhaust flange
to the roughing pump.
Replacing the roughing pump's oil demister element
TP02686
March 14, 2014, 715004387 Rev. B
1 mm exposed thread
after tightening
187