Lauper Instruments Mocon Ametek OX-TRAN 2/22, Operator'S Manual, Page: 12 / 83

Introduction OX-TRAN Model 2/22 Operator’s Manual
1-4 Revision R MOCON, Inc.
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 (usually a nitrogen/hydrogen mix). This process is illustrated in Figure 1-2 which
depicts a Film sample mounted in a standard OX-TRAN model 2/22 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 allow to exit through an
exhaust port.
The Carrier Gas (nitrogen and hydrogen) passes through a catalyst to remove any residual oxygen and
then 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 patented Coulox 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.
Figure 1-2: The OX-TRAN Model 2/22 Test Cell
Testing Films and Packages
The OX-TRAN model 2/22 can measure the oxygen transmission rate of film samples or entire packages.
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. The Test Gas and Carrier Gas supplied to the test cell can be Dry or at a
specified RH. For more information on testing Flat Film samples see Chapter 5.
To test packages at ambient temperature; a package mounted in an appropriate “fixture” can be connected
to the OX-TRAN model 2/22 using the optional Package Adapter. For more control over sample
temperature an Environmental Chamber can be used. For more information on testing packages see
Chapter 6.
Flush Gas In
Flush Gas Out Carrier In Carrier Out
Test Gas Out Test Gas In