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|  MIL-E-22200G
4.6.8.3 Conditioning procedure. The furnace shall be operated at 1650 to
(900 to
with an oxygen flow of 200 to 250 milliliters (mL) per
minute.
The nickel boat shall be placed in the combustion tube for drying and
the absorption U-tube shall be attached to the system for "conditioning." After
30 minutes, the absorption U-tube shall be removed and placed in the balance
case. The nickel boat shall be removed and placed in a desiccator in which
anhydrous magnesium perchlorate is used as the desiccant. After a cooling period
of 20 minutes, the absorption U-tube shall be weighed.
4.6.8.4 Blank determination procedure.
In the blank determination, the
procedure for an actual moisture determination shall be followed step-by-step
with a single exception of omitting the sample. The nickel boat shall be removed
from the desiccator and exposed to the atmosphere for a period approximating the
time required to transfer the sample from the balance pan to the boat. The
combustion tube shall be opened, the weighed absorption U-tube attached, the boat
placed in the combustion tube, and the tube closed. After a heating period of
30 minutes, the absorption U-tube shall be removed and placed in the balance
case. The nickel boat shall be transferred to the desiccator. After the 20
minute cooling period, the absorption U-tube shall be weighed and the gain in
weight shall be taken as the blank value.
4.6.8.5 Moisture determination procedure. Immediately after weighing the
absorption U-tube above, the sample covering shall be weighed on the balance dish
and quickly transferred to the boat. The combustion tube shall be opened, the
weighed absorption U-tube attached, the boat and sample transferred to the
combustion tube, and the tube closed. After an ignition period of 30 minutes,
the absorption U-tube shall be removed from the combustion tube and transferred
to the balance case. If another sample is to be run, the boat shall be taken
from the combustion tube, the ignited sample removed, and the boat transferred to
the desiccator. The absorption U-tube shall be weighed after the 20 minute
cooling period. Another determination may be started immediately and it is not
necessary to repeat the blank determination since the same combustion boat can be
used.
4.6.8.6 Calculation.
The calculation shall be made according to the
following formula:
Percent moisture -
Where:
A = gain in weight of absorption U-tube in moisture
determination, and
B = gain in weight of absorption U-tube in blank
determination.
4.6.9 Total iron content. The total iron content of the covering, as
specified in the applicable detail specification (see 3.1), shall be made by wet
chemical or spectrographic method. In the case of dispute, total iron content
shall be determined as specified below.
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