Supplying A Test Gas; Using Ambient Air For The Test Gas; Using A Compressed Gas For The Test Gas; Figure 7-4: Pouches And Bags - Top Mount - Ametek mocon OX-TRAN 2/12 R Operator's Manual

Testing Packages OX-TRAN Model 2/12 R Operator's Manual

Figure 7-4: Pouches and Bags - Top Mount

Supplying a Test Gas

To perform a transmission rate measurement a Test Gas must be applied to one side of the barrier material.
When testing packages the Test Gas is usually applied to the outside of the package fixture. How the Test
Gas is applied to the package fixture is usually dependent on the concentration of the gas that will be used.
The simplest way to apply a Test Gas to a package is to use ambient air. After the package fixture is
connected to the instrument no additional steps are required.
Using an oxygen concentration for the Test Gas that is higher or lower than ambient air requires additional
steps when creating the package fixture. The package fixture must be modified to allow a test gas to be
applied to the outside of the barrier material. This is usually done by sealing the package fixture into a bag
containing tubing that allows a Test Gas to purge the bag (see Figure 7-5).

Using Ambient Air for the Test Gas

Using ambient air is the simplest way to supply a test gas. The transmission data however, will be affected
by changes in the ambient temperature and RH. Placing the packages in an environmental chamber will
minimize the effects of ambient temperature variation. Using an environmental chamber may not result in a
similar reduction in the effects of ambient RH variation on the transmission rate.

Using a Compressed Gas for the Test Gas

Using a compressed gas for the Test Gas has a number of advantages. The effect that ambient RH has on
the package is minimized (compressed gases are by nature dry (0% RH). The compressed test gas supply
displaces any ambient water vapor.
7-6 Revision L MOCON, Inc.