TB 9-6670-254-50
NOTE
Unless otherwise specified, verify the result of each test and,
whenever the test requirement is not met, take corrective
action before continuing with the calibration. Adjustment
required to calibrate the TI are included in this procedure.
Additional maintenance information is contained in NBS
Circular 3, Section V, and NBS Circular 547, Section I, for this
TI.
NOTE
Unless otherwise specified, all controls and control settings
refer to the TI.
7. Equipment Setup
NOTE
In order to have an accurate mass calibration, the accuracy of
the standard should be considered since the amount of error in
the standard may determine whether the TI is within
tolerance. For this reason, the Primary Laboratory Report for
the Class S and S-1 reference standard weights must be used.
a. Insure that balances (A1 through A3) are visually clean, free of obvious vibration,
direct sunlight, draft, and direct heat radiation.
NOTE
To perform calibration, establish center rest point on balance
before each TI weighing.
b. Clean TI with methyl alcohol and allow ambient stabilization of 4 hours for weights
1 pound or less, and 12 hours for weights over 1 pound.
c. The direct weighing method is to be used to check Class C, Q, and T commercial
weights. This method consists of using both double and single pan balances for comparing
the weights to Class S or S-1 standard weights.
NOTE
For convenience, table 1 shows the avoirdupois and gram
equivalent for the size weights utilized by Army calibration
teams (1 pound mass 453.59237 grams).