TA Instruments AR 2000, Operator'S Manual

Page: 106 / 144

AR 2000 Operator’s Manual
106
Maintaining the Cell
WARNING: Before removing the heating jacket from the rheometer or the cell from the
jacket, ensure that cell and manifold are not under pressure, and that the both are at
safe touching temperature. The pressure relief procedure is described above.
Cleaning the Pressure Cell Cup
The cup can be cleaned simply by washing it in solvent or other type of cleaner (water, etc.), depending on
the material being test, after removal from the heating jacket.
Cleaning the Rotor Assembly
CAUTION: When cleaning the rotor, observe the following precautions:
(1) Do not apply a sideways force to the rotor. Doing so can bend, break, or otherwise
damage it. If a bent rotor shaft is suspected (will not rotate freely), hold the rotor
assembly horizontally by the upper body (do not hold by the rotor), and spin the rotor
while observing the edge. No discernible wobble should be seen as the edge of the
rotor rotates.
(2) Do not allow sample or solvent to flow upward into the upper portion of the body
of the rotor assembly, as this may result in a change in the friction of the sapphire
bearings.
If sample fluid has flowed into the sapphire bearings and magnet of the rotor assembly, the rotor may become
"sticky" (not rotate freely). In this case, the rotor assembly must be dismantled and cleaned as follows:
1. Hold the rotor assembly by the upper portion only. Be careful not to bend the rotor shaft—see Caution #1
above.
2. Place the tips (bent at 90°) of the supplied pliers into the holes of the locking nut and unscrew the nut by
rotating counterclockwise (anticlockwise).
3. Remove all inner components by gently pulling the rotor straight out of the assembly. Clean the inner
components using an appropriate solvent. Cellophane tape can be used to clean surfaces that have been
contaminated by solid particles, but be certain that no adhesive residue remains on the components.
4. If sample has flowed to the upper sapphire bearing, remove the thumbscrew and clean the inner
components using solvent.
5. Reassemble the pieces in the reverse order, being careful not to overtighten the locking nut (hand-tight is
sufficient).
NOTE: Typically, sapphire bearings are designed to work "dry." The Pressure Cell is therefore
supplied without lubricant. However, it has been found that a small amount of suitably
compatible grease applied to the bearings can reduce the risk of a "sticky" bearing following
contamination of the bearing by condensation or overflow of sample fluid.