be removed or added. These wells are located beneath the knob at the top of the weight.
The knob may be unscrewed revealing a pocket or well large enough to remove or add
extra weight (lead pellets) to bring the weight within a specified tolerance. If after
removal of all the extra weights, the standard is not within tolerance, it may be necessary
to drill out an extra amount. In most cases this weight will be in very small amounts and
the calibrator should be very certain of the measurements taken before drilling a weight.
Standards which have these screw knobs or other means by which adjustment is possible
without destroying the seal will not be sealed.
6. Weighing equipment.
a. Voland 600 (equal arm balance).
(1) Equal arm balance with graduated beam.
(2) Range, 0 to 250 grams.
(3) Sensitivity, 0.1 mg to full load.
(4) Secondary reference equipment (AACL).
b. Troemner model 175G (equal arm balance).
(1) Range, 10 to 200 lbs.
(2) Secondary reference equipment (AACL).
(3) Sensitivity, 0.4 grain at 10 lb (Approx 25 mg)
1.0 grain at 200 lb (Approx 65 mg)
c. Voland J5000S (single pan balance).
(1) Single pan balance with a digital readout.
(2) Range, 0 to 5000 grams.
(3) Sensitivity, 1 mg.
(4) On scale range, 1 gm.
(5) Secondary reference equipment (AACL).
7. Measurement Methods. Some of the methods used for weight measurements are as follows:
a. Direct method - Place the sample (unknown) weight on one of the pans suspended
from one of the beam (lever) arms, and the calibrated weights on the other pan.
b. Transposition method - Perform two successive direct weightings, reversing the
sample and weight positions in the second weighing.
c. Substitution method - Place the unknown in the right pan and counterbalance with
calibrated metal weights placed in the left pan. Bring the balance into equilibrium, first