Ametek Chandler Engineering 8040D10, Instruction Manual

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3-2 MAINTENANCE OF CONSISTOMETER
If the threads are damaged, the thermocouple may blow out under pressure. Inspect the
exterior of the probe for thinning or nicking. Replace any or all components as required.
Monthly
Potentiometer Mechanism
The potentiometer mechanism must be completely disassembled and cleaned. If any of the
following components exhibit signs of wear, they must be replaced as follows.
Resistor Replacement
1. Remove the Shaft Bearing Retainer and Contact Arm.
2. Remove the old Resistor, using care not to damage the slot.
3. Position the new Resistor straight side down with equal overlap from the Contact Strips to
the end of the winding.
4. Seat the Resistor firmly in the slot (use a block of wood to press into position). The top
surface of the Resistor must be level.
5. Burnish the resistance wire lightly by rubbing the top surface with a hardened drill rod
shank. This will ensure that the Contact Arm slides smoothly.
6. Rotate the Contact Arm by hand. Affirm that the arm rotates smoothly and maintains
contact with the Resistor from Contact Strip to Contact Strip with no dragging. If
necessary, adjust the arm by bending it up or down.
7. Adjust the position of the Stop Arm on the Center Shaft in order to obtain strip-to-strip
travel of the Contact Arm. All set screws must be tight.
8. Replace the Shaft Bearing Retainer.
9. Calibrate the Potentiometer.
Calibration Spring Replacement
1. Remove the Shaft Bearing Retainer and Contact Arm.
2. Remove the old Calibration Spring.
3. Install a new spring (when the center shaft of the Potentiometer Mechanism is turned
counterclockwise, the spring is wound tighter).
4. Replace the Contact Arm.
5. Loosen but do not remove, three screws on underside
6. Rotate the Spring Adjuster until slack is out of the spring and the Contact Arm lines up
with the Contact Strip. Tighten the screws.
7. Replace the Shaft Bearing Retainer.
8. Calibrate the Potentiometer.
Potentiometer Calibration
Depending on the frequency of its use, the potentiometer mechanism should be recalibrated
regularly and whenever the spring, contact arm, or resistor is adjusted or replaced. Higher
operating temperatures in the pressure chamber require more frequent recalibration of the
potentiometer.