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10
7. Check the movement of the rotor. To test for resistance, move a magnet
or magnetized metal object around the outside of the cell at the same
level as the rotor magnet. The rotor should turn freely inside the cell as
the outside magnet moves.
If the rotor does not move freely, remove it from the cell. Thoroughly clean
the rotor and magnet and inspect the bearing inside the outer race on the
rotor (see page 38). Also check the rotor bushing for damage or wear.
8.
Pour 140 mL of test fluid into the cell.
Be careful not to get any of the sample on the threads or seals. The
fluid level should be about
3⁄16
" below the top of the rotor.
9. Check the movement of the rotor again (see step 7 above). This will help
the test fluid fill the void space between the cell wall and the rotor.
10. Slide the bob shaft up through the coupling and screw it into bottom of the
torsion spring assembly.
11. Slide the cell body under the coupling and screw it into place.
Watch the torque magnet closely as you turn the cell. Just before the
cell tightens completely, the torque magnet should lift up about 3 - 5 mm.
This is caused by the pivot on the test cell inner race engaging with the
jewel bearing on the bob. The pivot will push up on the bob and bob shaft
which are connected to the spring assembly.
Once the torque magnet begins to lift, stop tightening the cell. Check the
movement of the torsion magnet. It should move up and down slightly. If it
does not, the pivot may not have properly engaged with the jewel bearing.
Unscrew the test cell and try again.
Once you confirm that the pivot has properly engaged with the jewel
bearing, finish tightening the test cell.
If you feel resistance while screwing in the cell, stop immediately
and slowly unscrew it. Never force the cell to tighten. Make sure
the threads are lubricated with high-temperature thread lubricant
(#165-44).
