(1) Controls. Two knobs (left side front) dial in
(1) To weigh a sample of unknown weight, use
the weight knob to return the macro weight counter to
the weights from 1 to 99 grams. The release lever is
turned down and the weight is read to the last decimal
micrometer line on optical scale.
place by superimposing a hairline on the optical scale
(2) Move arrestment lever to the PREWEIGHT
with the micrometer control knob (right side front). The
weight application knobs and readout are arranged in a
straight line, in their logical sequence form left to right.
indicate zero, refer to paragraph 1 for calibration and
(2) Single field of view. The pan, optical scale,
and controls are in a single field of view.
After the scale is zeroed, arrest the balance
(3) Weighing chamber. Sliding glass doors on
by depressing the arrestment lever to the ARREST
either side provide access to the weighing chamber. A
pan brake which acts on the bridle above the chamber
(4) Place the arrestment lever in the down position.
provides damping of pan swing.
(4) Ionizer. The analytical balance is operated
Adjust the optical scale to zero by using the zero adjust
with an ionizer positioned near the weighing pan to
(5) Place a sample on the pan and lift the
dissipate static charges. The ionizer operates on the
following nuclear principles: Alpha radiation is emitted
arrestment lever to PREWEIGH position. The coarse
from the polonium elements and is harmless externally.
weight will be indicated on the optical scale.
Alpha rays travel through the air very rapidly, but have no
Set the weight control knobs to show the same weight on
power to penetrate the skin. As the rays travel through
macro weight counter.
the air, they produce dense ionization. It is this ionized
(6) Depress the arrestment lever to ARREST
air that dissipates static charges.
position and, after a brief pause (about 3 seconds), move
the arrestment lever to FULL RELEASE position (fig. 2-
22). When the optical scale comes to a stop, use the
micrometer drum knob to move the scale pointer
MODEL 2400-2463. The radioactive
(micrometer line) over the next lower optical division of
Isotope Polonium 210 is toxic and
the moving scale. The readout can then follow from left
ingestion or inhalation of the solid
to right: first the macro values from the macro weight
material should be prevented. Do not
counters, then the first two decimal places on the optical
remove the protective grid or touch
scale, and the final two digits from the micro (digital)
the radioactive strip under the grid. If
the strip is accidentally touched or
(7) Return fine adjustment to zero at the
handled, wash hands immediately
completion of each weighing.
with soap and water. The Ionizer is
(8) The taring capabilities of the balance can be
made by sealing Polonium between a
used on containers weighing less than 1 gram.
base of silver and a layer of gold.
Zero the balance; then place the container on the pan.
The element is then protected by a
The reading on the optical scale is the tare weight of the
shield and grid which prevent direct
(9) After taring, if it is desired to fill the container
be decayed to a nonradioactive
with a specific volume, adjust the zero control knob to
substance when the device is no
reflect zero on the optical scale and proceed as follows:
longer effective as a static eliminator.
(a) Remove the container from the analytical
The small quantity of remaining
balance and place it on the double beam balance.
material may be a potential hazard if
(Tongs should be used).
mishandled. Return for disposal if
(b) Tare the container on the double beam
use is to be discontinued. DO NOT
balance and proceed to fill it.
DISCARD AS SCRAP. DISPOSE AS
b. Operation (fig. 2-21).