TA Instruments AR 2000, Operator'S Manual

Page: 108 / 144

AR 2000 Operator’s Manual
108
8. Clean the inner components using an appropriate solvent ( e.g ., alcohol, acetone). Cellophane tape can be
used to clean magnet surfaces that have been contaminated by solid particles, but be certain that no adhesive
residue remains on the components.
9. If sample has flowed to the upper sapphire bearing, remove the thumbscrew and clean the inner
components using solvent. A pipe cleaner can be used to clean inside surfaces.
Reassembling the Rotor
Make sure all of the parts are dry after the cleaning process and follow the steps below to reassemble the pieces.
10. Slide the sapphire bearing holder onto the magnet shaft making sure the flat side is facing towards the
rotor (which will be on the bottom).
11. Slide the locking nut over the shaft with the plier holes facing toware the rotor.
12. Align the magnet's mark with the rotor alignment ring, insert the shaft into the rotor, and make sure the
shaft bottoms out in the rotor.
13. Tighten the two setscrews on the rotor, using a torque wrench to adjust the
setscrews to 8.5 lbf-in or .96 N-m.
14. Turn the rotary cap upside down and rest it on a flat surface (table or lab
bench).
15. Taking the parts already loosely assembled, insert the shaft into the rotary
cap until you feel it hit the bottom. You may need to move it around slightly
until it drops all the way through. The tip of the shaft should be visible at
the top of the rotor as seen in the figure to the right.
16. Using the 90°pliers, screw down the lock-
ing nut by rotating it clockwise. See the
lower right-hand figure. (You may find it
easier to tighten the nut by rotating the
rotary cap counterclockwise and holding
the locking nut steady with the pliers.)
17. Watch the top surface of the locking nut as
it is tightened. Once the locking nut's top
surface is even with the cap, the shaft must
be fully inserted in the sapphire bearing as
directed in step 15.
The rotor will rest on top of the 90° pliers
if the shaft is correctly located inside the
sapphire bearing.
DO NOT CONTINUE TIGHTENING
UNTIL THIS IS VERIFIED. THE BEAR-
INGS MAY BE DAMAGED IF THE
SHAFT IS NOT INSIDE BOTH BEAR-
INGS BEFORE TIGHTENING COMPLETELY.
Figure 8.26
Reassembling the Rotary Assembly
Rotor
Locking Nut
Top Surface
Rotary
Cap