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OX-TRAN Model 2/12 R Operator's Manual
The Sample Conditioning Time
When you condition a sample in the test cell, carrier gas and test gases are routed to the test cell as they
are during testing. However, the carrier gas is not routed to the Permeant sensor. This conditioning period
allows a sample barrier to acclimate to the conditions within the test cell.
During individual zero processing nitrogen is used as the test gas. When you use individual zero processing
the sample will actually be conditioned twice, once in nitrogen before individual zero testing and once in
oxygen before oxygen transmission rate testing.
Some barrier materials may take a long time to reach equilibrium, a conditioning period offers two
advantages when performing a test:
•
It prevents unnecessary exposure of the Permeant sensor to oxygen, thus extending the life
of the sensor.
It limits the number of transmission rate values that appear on a printed report.
•
The amount of time in hours that the sample is conditioned can be specified. After the specified conditioning
period the system will automatically begin testing or individual zero processing.
Individual Zero Processing
Adjusting the ReZero frequency will compensate for small shifts in the baseline zero. It may also be
necessary to compensate for individual variations such as edge leakage or edge effect in the test cells. This
is done with Individual Zero Processing.
During individual zero processing nitrogen is routed through both halves of the test cell. Any oxygen that is
picked up on the carrier gas side is thus due to factors other than permeation.
The instrument automatically subtracts this Individual Zero value from the oxygen transmission rate value to
produce a very accurate result.
Whenever you test a Very Good barrier you should perform individual zero processing. The settings for the
Individual Zero mode field are explained below.
None
Beginning/End
Use Last
MOCON, Inc.
When Individual Zero mode is set to "None" an Individual Zero phase
will not be performed. The default Individual Zero mode is "None".
When using these options, the individual zero value for the cell is
measured. This value is subtracted from the measured transmission
rate to give a corrected transmission rate value. The "Beginning" and
"End" settings indicate when the Individual Zero phase will be
performed at the Beginning or at the End of the test.
In this mode the latest individual zero value measured is used. This
value is subtracted from the measured transmission rate to give a
corrected transmission rate value. The mode is useful if making many
tests on the same type of material and the user is confident that edge
leakage is not a problem and every sample barrier is mounted the
same.
Revision L
Preparing for a Test
3-3
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