OX-TRAN Model 2/22 Operator’s Manual
Preparing for a Test
MOCON, Inc.
Revision R
3-1
Chapter 3: Preparing for a Test
This chapter provides information on how to prepare for a permeation test.
Read this chapter to learn about:
•
Testing Basics
•
How Barrier Properties Affect Testing
•
Developing Test Methods for Films and Packages
•
Developing a Temperature Profile
Testing Basics
A permeation test is comprised of a series of discrete actions or events. Some of these steps require human
thought, action or intervention. Some of the steps are performed by the instrument and will be discussed
elsewhere. The most important part of the process is the planning and preparation that occurs before the
actual testing begins. Inadequate planning or preparation may result in an inaccurate measurement. This
chapter contains information on the factors that should be considered when planning for a permeation test.
How Barrier Properties Affect Testing
A good understanding of the barrier material properties for the samples to be tested is very helpful when
preparing for a permeation test. The transmission rate of the sample and the conditions at which it will be
tested may require changes to the test methodology.
Any sample with a transmission rate within the range of the instrument (as specified in Chapter 9) can be
tested. Additional consideration is advised when setting up tests for samples that are Very Good or Very
Poor barriers. A Very Good Barrier is generally considered any material with a transmission rate less than
0.1 cc / (m
2
• day) or 0.0005 cc / (pkg • day). A Very Poor Barrier is generally considered any material with a
transmission rate greater than 100 cc / (m
2
• day) or 0.5 cc / (pkg • day) when using a 100% oxygen test
gas.
Testing Very Good Barriers
When testing Very Good Barrier film samples use as large a sample as possible, masking is not normally
advised. Longer Cell Examination and ReZero Examination times may be required. An Individual Zero test
phase is recommended when testing Very Good Barriers.
Testing Very Poor Barriers
Use caution when testing Very Poor Barriers an excessively high transmission rate will over-range the
oxygen sensor. Persistent or repeated over-range conditions can damage the Coulox sensor. Common
poor barrier materials include polyethylene, polycarbonate and acrylic.
There are two ways to reduce the possibility of an over-range when testing poor barriers:
•
Reduce the oxygen concentration of the Test Gas
•
When testing film samples use a mask to reduce the sample area.