Torsional Spring Dynamometer Model NLJ-A
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Torsion spring dynamometer is designed for use in recalibrating the Torsion Springs for rotational viscometers. Torsion springs must be removed from the instruments in order to perform this calibration. This instruction describes checking and adjusting the strength of the torsion spring such that a known torque will produce a known deflection, (dial reading). In this calibration known weights will be used to produce a known amount of angular rotation of the bob shaft, or dial reading. The Newton-cm of torque/degree of dial deflection is known as the K1 factor. The K1 (spring factor) is adjusted by adjusting the active length of the spring.
The Calibration Fixture may be used for:
Calibration of a replacement spring when it being installed.
Verification of calibration of the spring bealready in the instrument.
Re-calibration of the spring be already in the instrument.
Check the following parts of the Rheometer for runout or damage. If any of these parts are bent or otherwise damaged, repairs must be made before a successful calibration can be performed. Check the following:
Bob Shaft and Bob for runout –Straighten or replace. Maximum total runout allowed is 0.005 in. (0.127 mm)
Sleeve for runout — Straighten or replace.
Maximum total runout allowed is 0.005 in. (0.127 mm)
Deformed or damaged spring — Replace.
Mis-aligned dial “0” — Readjust zero, (Refer to Sections 3-F7 or 4-F9)
Torsion Shaft bearings defective –Replace