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Introduction
OX-TRAN Model 2/28 Operator's Manual
Measuring an Oxygen Transmission Rate
To make an accurate transmission rate measurement a known concentration Test Gas (usually 100%
Oxygen) is applied to one side of the barrier material to be tested and the other side is swept with an
oxygen free Carrier Gas (nitrogen). This process is illustrated in Figure 1-2 which depicts a Film sample
mounted in a standard OX-TRAN model 2/28 test Cell.
As shown in the illustration the film is mounted between the two parts of the test cell. The o-rings and
sealing surfaces in the cell prevent outside air from affecting the measurement.
The Test Gas (oxygen) is continuously admitted to bottom half of the cell and allowed to exit through an
exhaust port.
The Carrier Gas enters the top half of the cell. As Test Gas permeates the sample barrier it mixes with the
Carrier Gas. The output side (exhaust) of the test cell is routed to an oxygen sensor. The amount of oxygen
in the carrier gas is measured using the oxygen detector.
Seal leakage can be a significant source of error when measuring the transmission rate of a film sample.
The TruSeal™ flush ring at the perimeter of the Test Cell minimizes the effect of ambient oxygen on the
measurement. During a test, the TruSeal™ flush ring is purged with carrier gas minimizing the possibility of
leakage past (or permeation through) the seals.
Flush Gas In
Carrier In
Carrier Out
Flush Gas Out
Test Gas In
Test Gas Out
Figure 1-2: The OX-TRAN Model 2/28est Cell
Testing Films
The OX-TRAN model 2/28 is designed measure the oxygen transmission rate of flat film samples.
To test a film sample, it is prepared and mounted in a Test Cell. The test cell is used to maintain the film
sample at a specified temperature. For more information on testing Film samples see Chapter 5.
1-4
Revision J
MOCON, Inc.
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