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|  MIL-E-19141D
Oxygen flow.
7.
The flow of oxygen to the train shall be maintained at 200 to 250 milliliters
(mL) per minute. Once the flow of oxygen is established, it shall not be
changed throughout the determination.
Combustion boats.
8.
A nickel combustion boat which will
hold a 4-gram sample shall be used.
(The ignited sample can be removed
after the determination and the boat
in the heated zone of the combustion
reused. A small amount of alumina
fusing with combustion tube.)
tube will prevent nickel boat from
9.
Step by step procedure.
(a) Blank determination.
(1) With the furnace operating at a temperature of
the oxygen
flow shall be adjusted to 200 to 250 mL per minute. The nickel
boat shall be placed in the middle of the heated zone of the
combustion tube and the absorption U-tube attached to the train.
A period of 30 minutes shall be employed to ignite the boat and
condition the absorption U-tube.
(2) The moisture absorption U-tube shall be removed from the system
and placed in the balance case and the nickel boat shall be
removed from the combustion tube and placed in the desiccator.
The combustion tube of the furnace shall be closed after removing
the boat.
(3) After cooling for a period of 20 minutes, the absorption U-tube
shall be weighed. The boat shall be removed from the desiccator
and exposed for a period of time approximating the time required
to transfer a sample from the balance pan to the boat in an actual
determination.
(4) The combustion tube shall be opened, the moisture absorption U-tube
placed in the system, the boat placed in the center of the com-
bustion tube and the cover replaced.
(5) After a period of 30 minutes, the absorption U-tube shall be removed
from the system and placed in the balance case and the boat shall
be removed from the combustion tube and placed in the desiccator.
(6) The moisture absorption U-tube shall be weighed after a period of
20 minutes. The gain in weight is the blank.
(b) Moisture determination.
(1) Immediately after weighing the absorption U-tube in item 6 of the
blank determination procedure, the sample shall be weighed out
on the balance pan.
(2) The boat shall be removed from the desiccator and the sample
quickly transferred from the balance pan to the boat.
(3) The combustion tube shall be opened, the moisture absorption U-tube
placed in the line, the boat transferred to the center of the com-
bustion tube and the cover replaced.
(4) After a period of 30 minutes, the absorption U-tube shall be removed
from the system and placed in the balance case.
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