OxyPerm Permeation Chamber · 2020. 8. 27. · 4.0 Permeation Chamber Overview The permeation...

OxyPerm® Permeation Chamber

Users Guide© Industrial Physics Product Integrity

OxySense An Industrial Physics Product Integrity Brand

68 Branum Road, Devens, MA 01434. USAPhone: (978) 772-0970

Website: www.oxysense.com Email: [email protected]

Technical Support email: [email protected]

Document Revised: July, 2020Information in this document is subject to change without notice. Any reference to a company or data used as examples herein is fictitious unless otherwise noted. No part of this document may

be reproduced or transmitted in any form or by any means for any purpose without express written permission.

All other company and product names are the trademarks or registered trademarks of their respective companies.

All Rights Reserved

https://www.oxysense.com/

mailto:[email protected]


Document update: July 2020Copyright © Industrial Physics Product Integrity All Rights Reserved

Information in this document is subject to change without notice. All company and product names used herein are the trademark or registered trademarks of their respective owners. Referencing a company or data found herein, for any purpose without express written permission, is prohibited.

Alway follow all local and national safety guidelines and any additional safety guidelines specific to your organization. Consult with your organization’s safety officer prior to performing work.

Electronic equipment should be protected for unexpected electrical events such as power dips and surges. Consult your organization’s electrical engineering officer prior to installation and operating electrical equipment.

Any description of standards, protocols, practices, or procedures are given as guidance and may not fully align with the standards, protocols, practices, or procedures of your organization’s quality assurance pro-gram. Consult your organization’s quality assurance officer prior to beginning work.

Table of Contents

1.0 Introduction ................................................................................. 1

2.0 How it works ................................................................................. 22.1 Instrumentation ........................................................................... 2 2.2 Dynamic Accumulation ................................................................ 22.3 Film Permeation Tests.................................................................. 2

2.3.1 Test Parameters .................................................................. 32.4 Visulation DA .............................................................................. 3

3.0 Equipment, Material and Supplies ..................................................... 43.1 Equipment ................................................................................. 43.2 Materials ................................................................................. 43.3 Supplies ................................................................................. 4

4.0 Permeation Chamber Overview .......................................................... 5

5.0 Gas Cylinders and Flow Meters .......................................................... 7

6.0 OTR Determination -Test Setup ......................................................... 86.1 Placing Film in the Chamber ........................................................... 86.2 Purging the Sensing Well ................................................................ 106.3 Purging the Sensing Well (optional) ................................................. 12

7.0 Data Acquisition ............................................................................ 147.1 Overview of the Film Permeation Module ......................................... 157.2 Creating a Permeation Test File ...................................................... 207.3 Configuring Test Parameters ........................................................... 227.4 Acquiring Data ............................................................................... 25

7.4.1 Time Intervals ..................................................................... 267.4.2 Frequently Asked Questions aout Time Intervals ................. 277.4.3 Using the Timer Feature ..................................................... 28

8.0 Data Analysis ................................................................................. 308.1 Data Quality Indicators .................................................................. 30

8.1.1 The OTR Graph ................................................................... 308.1.2 The Oxygen Graph .............................................................. 31 8.1.3 The R2 Value ....................................................................... 31

OxySense Gen III - Operations Manual

9.0 Data Interpretation ............................................................................ 329.1 The Conditioning Phase .................................................................. 329.2 Rejecting Data ................................................................................ 33

9.2.1 Gen III Software .................................................................. 33

10.0 Trouble Shooting ........................................................................... 35

11.00 Technical Support ............................................................................ 36

Appendix A: .. O2XYDot® Calibration .......................................................... A-1

Appendix B:.. Basic Principles of Film OTR by Dynamic Accumulation ... B-1

List of Figures Figure 2-1: DA Visualization ................................................................. 3 Figure 4-1: Permeation Chamber Disgram (Exterior) ............................. 5Figure 4-2: Permeation Chamber Diagram (Interior) .............................. 6Figure 5-1: Flow Meter Attachment Diagram ........................................ 7Figure 5-2: OxySense Flow Meter .......................................................... 7Figure 8-1: The OTR Graph .................................................................. 30Figure 8-2: The Oxygen Graph ............................................................. 31Figure 8-3: The R2 Value ...................................................................... 31Figure 9-1: Conditioning and Permeation Phases .................................. 32

Permeation Chamber User’s Manual Page 1

Copyright © Industrial Physics Product Integrity 2020

1.0 Introduction

The OxyPerm Permeation Chamber is manufactured exclusively by Industrial Physics Product Intergrity, Devens, MA, U.S.A.and is designed for the purpose of determining oxygen transmission rates(OTR) of flat, polymer films when used in conjunction with an OxySense® 5000 series oxygen analyzer. The Permeation chamber is part of OxySense’s OxyPerm line oxygen analysis accessories.

OxySense 5000 series instruments are equipped with OxySense’s Gen III software which includes the modules required for capturing oxygen permeation data and calculating the OTR of films reported in either milliliters (cubic centimeters) per square-meter per day (ml/m2/day) or milliliters per 100 square-inches per day (ml/100in2/day).

The remainder of this document discusses how to perform the following tasks:

• Setup the permeation chamber for OTR determination

• Calibrate the permeation chamber’s O2xyDot® oxygen sensor

• Use the Gen III software to capture data for OTR Determination

• Generate OTR reports


2.0 How it Works

The information contained in the following subsections is provided to “demystify” OTR analysis. Your understanding of the method and the instrumentation will greatly increase the ease of producing a valid OTR result.

2.1 Instrumentation

Using an OxySense® instrument, one is able to obtain non-invasive (i.e. in-situ) oxygen concentration measurements by way of fluorescence quenching analysis, where, an optical, oxygen-selective sensor (e.g. an OxyDot®) resides within a sealed container, affixed to a transparent surface. The instrument is capable of capturing the optical signal from the sensor and transducing the signal in to an oxygen concentration.

The OxyPerm® Permeation Chamber is equipped with an OxyDot® that resides within the chamber, opposite a transparent reading window. An OxySense® 5000 series instrument is used to capture an oxygen concentration reading from the sensor without disturbing the integrity of the chamber. The space where the OxyDot® resides is isolated from the oxygen-containing atmosphere by the material being analyzed.

2.2 Dynamic Accumulation

OxySense employs the principle of dynamic accumulation (DA) for OTR determination, where oxygen gas that permeates through the material gradually accumulates within a container. OxySense® instrumentation, which is ideal for the in-situ measurement of oxygen accumulation, is used to record the increasing oxygen concentration within that container over time. The OTR is then calculated from the oxygen accumulation data.

2.3 Film Permeation Tests

When determining OTR by DA using the OxyPerm® permeation chamber, the portion of the chamber where the OxyDot® resides, called the sensing well, is first purged with an inert gas (i.e. nitrogen) rendering the volume surrounding the sensor free of oxygen. The portion of the well opposite the sensing well is called the driving well, the volume of which is filled by an oxygen-containing gas (e.g. pure oxygen or air).

As gas crosses from the driving well through the film and in to sensing well, the oxygen concentration rises. Data is captured periodically over time. The recorded oxygen concentration and time data is then used to calculate the OTR as the oxygen and time data are both directly correlated to the permeability of the film.



2.3.1 Test Parameters

The key parameters that must be known prior the test are 1) the oxygen concentration in the driving well, 2) the surface area of the film exposed to the sensing well, and 3) the volume of the sensing well.

2.4 Visualizing DA

The following diagram illustrates what is happening in the permeation chamber throughout the test. It is provided to visualize what occurs throughout the course of the test. Please note that this is a simplified visualization provided only as a visual aid.

Figure 2-1: DA Visualization

N2

N2 N2

N2 N2

N2 N2

N2 N2

O2

O2 O2

O2 O2

O2 O2

O2 O2

O2 O2

N2

N2 N2

N2 N2

N2

N2 N2

N2

O2

O2O2

O2

O2O2

O2O2

O2O2

O2

O2

N2 N2

N2 N2

N2 O2

N2 N2

N2

O2 O2

O2 O2

O2 O2

O2 N2

O2 O2

N2

O2O2

N2

O2N2

O2O2

N2O2

O2

O2

N2 N2

ON2

N2 O2

O2 N2

At Time 0 (beginning of the test) the sensing well is filled with pure nitrogen and the driving well contains oxygen.

As time progresses, gas exchange occurs between the driving and sensing wells. The amount of oxygen in the sensing well increases.

At Time 1, the oxygen concentration in the sensing well has increased. Gas exchange continues

At Time n, the oxygen concentration in the sensing well has further increased. Time and oxygen data are used to calculate OTR.

Copyright © Industrial Physics Product Integrity 2020Copyright © Industrial Physics Product Integrity 2020


3.0 Equipment, Materials and Supplies

The following list gives the equipment, materials and supplies needed to perform OTR determination using the OxySense® Permeation Chamber. All items are required for a test except for those that are optional as noted.

3.1 Equipment

• OxySense® 5000 series oxygen analyzer

• OxySense® Permeation Chamber

• Gas flow meter, 0.05 L/min (0.1 SCFH)

3.2 Materials

• Gas tubing, ¼” (6mm) O.D., nylon or similar

• Gas-tight fittings and connectors

3.3 Supplies

• Nitrogen cylinder, 99.99+% pure, < 1ppm oxygen by volume

• High vacuum grease, Dow-Corning or similar

• Non-abrasive tissue, Kimwipe® or similar

• Oxygen cylinder, 99.99+% pure (optional)

• Air cylinder, certified 21% oxygen (optional)



4.0 Permeation Chamber Overview The permeation chamber is assembled and tested at the OxySense manufacturing facility. The following diagram depicts the permeation chamber and its assembled components.

Serial Number

Reading Pen Insertion

Locking Bolts

Sensing Well Outlet Sensing Well Inlet Driving Well Outlet Driving Well Inlet

Figure 4-1: Permeation Chamber Diagram (Exterior)

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Perm

eatio

nCha

mbe

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A00

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(top view)

(side view)



Sensing Well

Driving Well

O2xyDot®

Sensing Well Outlet Sensing Well Inlet Driving Well Outlet Driving Well Inlet

Figure 4-2: Permeation Chamber Diagram (Interior)

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(interior view)

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5.0 Gas Cylinders and Flow Meters

The sensing well must be purged with an inert gas (nitrogen) prior to beginning a test. In order to do this without causing damage to the film, you must use a flow meter (e.g. rotameter) capable of maintaining a flow rate of 0.05 liters per minute (L/min) (0.1 standard cubic-feet per hour (SCFH)). A flow meter may be procured from OxySense or a gas supply retailer. The following figure depicts the connections between a nitrogen cylinder (99.99+% pure), a flow meter, and a permeation chamber.

You must use a two-stage regulator on the gas cylinder. It is recommended that you set the outlet pressure on the tank regulator to 70 kiloPascals (kPa) (10 pounds per square-inch (psi)). You may set the outlet pressure higher as long as you do not exceed the maximum pressure allowed by the flow meter and the flow meter is able to maintain a constant flow of 0.05 L/min.

IMPORTANT: The flow rate of gas through the permeationchamber should be set to 0.05 L/min (0.1 SCFH) and

must not exceed 0.1 L/min (0.2 SCFH). Flow rates greater than 0.1 L/min will pressurize the sensing well or the driving well, causing the film inside the chamber to distort, bulge, and possibly rupture. To ensure this does not happen, you must acquire and use a flow meter to regulate the flow of gas.

Gas Cylinder

Flow Meter

Permeation Chamber

Figure 5-1: Flow Meter Attachment Diagram

Gas Out

Gas In

Rotameter

Adjustment Knob

Check Valve

Figure 5-2: OxySense® Flow Meter

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6.0 OTR Determination – Test Setup

Film OTR is determined by placing a film sample in the permeation chamber, purging the sensing well with nitrogen (99.99+% pure), having a known concentration of oxygen in the driving well (either ambient or 100%), and collecting data over time. In this section you will learn how to perform the following tasks:

• Place film in the chamber

• Purge the sensing well

• Purge the driving well (optional)

IMPORTANT: Ensure that the OxyDot® has been calibrated according to the directions provided in Appendix A. You must calibrate the OxyDot® prior to OTR Analysis.

6.1 Placing Film in the Chamber

The first step in setting up a test is placing film in the chamber. To ensure that an gas-tight seal in maintained around the film, the chamber is equipped with a Viton o-ring which seals the film to the top-side of the chamber. Additional, vacuum grease is applied around the outer edge of the sensing will to adhere to the film to the top-side of the chamber and create and aid in sealing the film.

Film Placement Steps:

Step 1: Open all four valves on the chamber. Step 2: Loosen and remove the locking bolts.

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Step 3: Place the chamber on your working surface so that the interior of the chamber is facing up.

Step 4: Obtain a tube of vacuum grease. Using your fingers or a dull, non-abrasive utensil (e.g. a swab), create a thin ring of grease around the outer perimeter of the sensing well. The ring does not need to be more than 1 cm wide (3/8”)

Cut a sample of the film to be tested. The film sample should be cut in to a square approximately 6.5 x 6.5 cm (2.5 x 2.5”) in dimension.

NOTE: You should only handle the film by its edges. Try not to touch the portion of the film that will be exposed to the sensing well. Residual oil transferred to the film from your finger tips can alter the efficiency of the test.

NOTE: The dimensions of the film do not need to be exact. However, the film must be of sufficient length and width to ensure that there are no gaps between the chamber’s o-ring and the edges of the film.

6.5cm



Step 5: Center and place the film sample over the sensing well. Be sure that the film is positioned such that there will be no gaps between the o-ring of the bottom-side of the chamber and the edges of the film.

Step 6: If necessary, smooth out the film using your index finger. Begin by placing your index finger near the outer edge of the sensing well and gently glide your finger toward the out edge of the film. Work your way around the entire perimeter of the sensing well until all visible wrinkled have bee smoothed out.

NOTE: Do not to touch the portion of the film that is directly over the sensing well. Residual oil transferred to the film from your finger tips can alter the efficiency of the test.

Step 7: Close the chamber and insert the locking bolts. Tighten the locking bolts by turning clockwise.

IMPORTANT: Do not use a tool such as pliers or channel locks when tightening the locking bolts. OnlyHand-tighten the bolts. Over-

tightening the locking bolts can damage the o-ring or the threading on the locking bolt inserts.

6.2 Purging the Sensing Well

In this section you will learn how to purge the sensing well with an inert gas. The sensing well must be purged with an inert gas so that the initial oxygen concentration in the sensing well is 0%. In the proceeding steps, you will use high-purity nitrogen (99.99+% pure) to purge the sensing well.

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IMPORTANT: If you have not yet calibrated the O2xyDot®, proceed to Appendix A O2xyDot® Calibration. After calibrating the O2xyDot® you may proceed to Section 5.3 Purging the Driving Well

Sensing Well Purging Steps:

Step 1: Be sure that there is film in the chamber. If you have not placed film in the chamber, please go to Section 6.1 Placing Film in the Chamber

Step 2: Connect the regulator of a nitrogen cylinder (99.99+% purity) to the inlet of the flow meter using a length of ¼” gas tubing and tubing connectors with ferrules. Connect a length of ¼” gas tubing and tubing connectors with ferrules to the outlet of the flow meter.

Step 3: Open the tank valve of the certified gas cylinder and any check valves that may be installed on your regulator or flow meter.

The flow of gas will begin. Set the flow meter to a rate of 0.05 L/min (0.1 SCFH). Allow the gas to flow for 30 seconds to flush the connected tubing.

IMPORTANT: Flow rate must not exceed 0.1 L/min (0.2 SCFH). Flow rates greater then 0.1 L/min can cause damage to the film.

Step 4: Ensure that both of the valves at the top of the chamber are fully open.

1.0 .8

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.1 0.1 SCFH

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Step 5: Connect the outlet of the flow meter to the inlet valve of the top half of the permeation chamber using a length of ¼” gas tubing and tubing connectors with ferrules. Allow the gas to flow through the top of the chamber for 60 seconds.

Step 6: Close the valves to the sensing well in the following sequence: Close the inlet valve first and then quickly close the outlet valve.

IMPORTANT: You must close the inlet valve and then the outletvalve in that order. If you close the outlet valve before the inlet valve,

the sensing well will pressurize causing the film in the chamber to distort, bulge and possible rupture.

Step 7: Close the tank valve on the nitrogen cylinder and any check valves between the cylinder’s regulator and the flow meter.

Disconnect the tubing from the permeation chamber’s inlet.

Step 8: Proceed to one of the following sections:

If you plan to use ambient oxygen in the driving well, proceed to section 7.0

If you plan to purge the driving well with 100% oxygen, proceed to Section 6.3

6.3 Purging the Driving Well (optional)

In this section you will learn how to purge the driving well with concentrated oxygen (99.99+% purity). This is recommended for high barrier films, that is, films with OTRs of 50 cc/m2/day or less (3 cc/100in2/day or less). Alternatively, the driving well may simply be left opened to the atmosphere. Purging the driving well with concentrated oxygen will simply accelerate the film permeation test. When leaving the chamber open to the atmosphere, the film permeation test will take approximately five-times longer than when the driving well is purged with concentrated oxygen.

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IMPORTANT: Be sure to consult your organization’s Health and Safety director before acquiring and using concentrated oxygen in your facility. Be sure to comply with all local or state safety regulations.

If you plan to use atmospheric oxygen (i.e. air) in the driving well, you may skip this section and proceed to Section 7.0.

Driving Well Purging Steps:

Step 1: Be sure that there is film in the chamber and that the O2xyDot® is calibrated and that the sensing well has been purged with an inert gas (nitrogen).

If you have not placed film in the chamber, please go to Section 5.1 Placing Film in the Chamber.

If you have not purged the sensing well, go to Section 5.3 Purging the Sensing Well.

If you have not calibrated the O2xyDot®, go to Appendix A O2xyDot® Calibration.

Step 2: Connect the regulator of a concentrated oxygen cylinder (99.99+% purity) to the inlet of the flow meter using a length of ¼” gas tubing and tubing connectors with ferrules.

Step 3: Open the tank valve of gas cylinder and any check valves that may be installed on your regulator or flow meter.

The flow of gas will begin. Set the flow rate to 0.05 L/min (0.1 SCFH). Allow the gas to flow for 30 seconds to flush all connected tubing.

IMPORTANT: Flow rate must not exceed 0.1

L/min (0.2 SCFH). Flow rates greater then 0.1 L/mincan cause damage to the film.

Step 4: Ensure that both of the valves at the bottom of the chamber are fully open.

1.0.8

.6

.4

.2

.10.1 SCFH

!

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Step 5: Connect the outlet of the flow meter to the inlet valve of the top half of the permeation chamber using a length of ¼” gas tubing and tubing connectors with ferrules.

Purge the driving well for at least 4 minutes at 0.05 L/min (0.1 SCFH)

Step 6: Close the valves to the driving well in the following sequence: Close the inlet valve and then quickly close the outlet valve.

IMPORTANT: You must close the inlet valve and then the outlet valve inthat order. If you close the outlet valve before the inlet valve, the

sensing well will pressurize causing the film in the chamber to distort, bulge and possibly rupture.

Step 7: Close the tank valve on the oxygen cylinder and any check valves between the cylinder’s regulator and the flow meter.

Step 8: Disconnect the tubing from the permeation chamber’s inlet.

Step 9: Proceed to Section 7.0 Data Acquisition.

6.4 Temperature

The room(s) where the permeation chamber is stored and analyzed must be maintained within the range of 23±2°C while the test is in progress. This is necessary to ensure that results from your tests are comparable to results obtained by others.

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7.0 Data Acquisition

After setting up the permeation chamber for use in the film permeation test, you may proceed to acquire data using the OxySense® 5000 Series instrument and the Gen III Software.

As stated in Section 2.0 How It Works, the film permeation test is carried out by monitoring and recording the incremental increase in oxygen concentration in the sensing well over time. The rate at which oxygen permeates in to the sensing well is calculated by the software and is used to determine the OTR of the film in either mL/m2/day or mL/100in2/day.

Data points are acquired by capturing readings from the permeation chamber’s O2xyDot® which is visible through the reading window located on the top portion of the permeation chamber, situated above the sensing well. The data is recorded in % (v/v) oxygen concentration or partial pressure of oxygen (PO2) in millibar (mbar).

This section will guide you through the film permeation test setup in the Gen III software. The following items are included in this section:

• Overview of film permeation software features

• Creating a test file in the Gen III Software

• Configuring test parameters

• Acquiring data

In section 8.0 Data Interpretation you will learn how to monitor the progress of a film permeation test, how to work with data, and how to determine when a test is complete.

7.1 Overview of the Film Permeation Module

This section discusses the features of the Film Permeation module. The Film Permeation module is the portion of the Gen III software which is used for film permeation test and is located in the Film Permeation tab in the software. There are two screens you will see when using the Film Permeation module:

• The Oxygen Permeation Tests screen

• The OTR screen

The following figures depict the two screens listed above. An explanation of the features in each screen is given below each figure.



Open Button

Browse Active Button

Browse All Button

View Log File Button

View Graph Button

Capture Button

Setup Button

Timer Button

Print Report Button

End Test Button

Chamber Serial Number Box

Test Name Box

Open

Opens the current test for the permeation chamber with the serial number specified in the Chamber Serial Number box. If there is no active test for the specified chamber, the software will prompt you to create a new test. If it is the first time that you have used a permeation chamber with your instrument, the software will prompt you to add the permeation chamber to the system.

Browse Active

Opens the Browse Active window which contains a list of active tests for all permeation chambers currently in use with the instrument. You may also perform such tasks as Change Test Description and Export to CSV in the Browse Active window.

Browse All

Opens the Browse All window which contains a list of active and closed tests for all permeation chambers that have been used with the instrument. You may also perform such tasks as Change Test Description and Export to CSV in the Browse All window.

View Log File Opens the OTR screen and displays a table of the recorded oxygen values for the active test associated with the specified permeation chamber.

B

A

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View Graph Opens the OTR screen and displays a data plot of the recorded oxygen values over time for the active test associated with the specified permeation chamber, respectively.

Capture Records a data point to the active test associated with the specified permeation chamber.

Setup Opens the Setup window for the active test associated with the specified permeation chamber. The Setup window is further discussed in Section 7.3 Configuring Test Parameters.

Timer

Activates the timer which enables automated capturing of data points at a specified time interval. The timer interval can be specified in the OTR screen.

NOTE: When using automated data acquisition, you must leave the instrument’s reading pen in the permeation chamber associated with the active test. The timer feature is only useful if you are running a single test with a single permeation chamber. If you are running multiple tests using multiple permeation chambers, you will not wish to use the timer.

Print Report Opens the Print Report window which allows you to either print the report to a printer attached to one of the instrument’s USB ports or export the report to a PDF file saved on the instrument.

End Test Ends the active test associated with the specified permeation chamber.

NOTE: Ending a test will prohibit you from adding data points to the test. Only end a test if you are satisfied with the results.

Chamber Serial

The box where you will enter the serial number of the chamber used for the test. You may enter the serial number by using a keyboard attached to the instrument, the on-screen keyboard in the software, or by scanning the chamber’s bar code using the optional bar code scanner attached to one of the instrument’s USB ports.

Test Name Displays the name of the open test.



Data Display Options

Test Identifiers

OTR Result

R2

Data Display Area

Calibration Factors

X-Axis Options

Select Log Button

Timer Interval Options Delete Data Point Button

Capture Button

Setup Button

Timer Button

Print Report Button

End Test Button

Data Display Selection

Allows you to select what information to display in the Data Display Area. Display options in the Log row display data in tabular format. Display options in the Graph row display data in graphical format. For example, the Oxygen Log will display a table of oxygen concentrations of all data points. The Oxygen Graph will display a plot of all oxygen concentrations over time.

Test Identifiers The test name and associated permeation chamber serial number.

OTR Result Displays the calculated OTR result for the current test. By default, the OTR value is displayed in mL/m2/day. This may be changed to mL/100in2/day in the Setup window. The setup window will be explained in Section 7.3

R2

Displays the coefficient of determination which indicates the “goodness of fit” of the data points used to calculate the rate of oxygen accumulation. The R2 value should be greater than 0.95. Use of the R2 as a data quality indicator is better explained in Section 8.0

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Data Display The box where data for the test is displayed in either tabular or graphical format. The format of the data in the box in selected from the data display options.

Calibration Factors Displays the dA and dB values for the O2xyDot® in the permeation chamber.

X-AxisAllows you to select the scale of the X-Axis for the graphical display of data. Choose an axis scale appropriate for the time interval between data points.

Select Log Returns you to the Oxygen Permeation Tests screen.

Timer Interval

Allows you to set the time between readings when the timer is activated. The Timer Interval dropdown box allows you to select the unit of time you wish to set for the timer. Only seconds and minutes are available. To set the timer interval to a number of hours, convert hours to minutes by multiplying by 60.

Delete Data Point

Allows you to delete a data point from the Oxygen Log. Deletion of data points should only be done for justifiable technical reasons as discussed in Section 8.0.

NOTE: A deleted data point cannot be retrieved.

Capture Records a data point.

Setup Opens the Setup window which is where you may perform such tasks as changing units of measurement. The Setup window is further discussed in Section 7.3

Timer

Activates the timer which enables automated capturing of data points at a specified time interval. The interval between readings in specified using the Timer Interval options.

NOTE: When using automated data acquisition, you must leave the instrument’s reading pen in the permeation chamber associated with the active test. The timer feature is only useful if you are running a single test with a single permeation chamber. If you are running multiple tests using multiple permeation chambers, you will not wish to use the timer.

Print Report Opens the Print Report window which allows you to either print a data report to a printer attached to one of the instrument’s USB ports or export the report to a PDF file saved on the instrument for later retrieval.

End Test Ends the test.

NOTE: Ending a test will prohibit you from adding data points to the test. Only end a test if you are satisfied with the results.



7.2 Creating a Film Permeation Test File

When setting up a film Permeation Test, it is necessary to create what is referred to as a Test File. The test file can be given a descriptive name (up to 17 characters) and will contain all of the pertinent information associated with a test including the permeation chamber serial number, the O2xyDot® calibration factors, the volume of the sensing well, the concentration of oxygen in the driving well, and all data points recorded during the test.

In this section you will learn how to create a test file in the Gen III software

NOTE: The term Test File is a misnomer as the data for a single test is not actually stored in its own dedicated file. Data points associated with a film permeation test are stored in the OxySense Gen III software’s database.

Steps for Creating a Test File

Step 1: With the OxySense Gen III software running, click on the Film Permeation tab.

Step 2: Enter the serial number of the film permeation chamber by using a keyboard attached to the instrument, the on-screen keyboard in the software, or by scanning the chamber’s bar code using the optional bar code scanner attached to one of the instrument’s USB ports. After entering the chamber serial number click the Open button.

Step 3: If this is the first time using the permeation chamber with your instrument, you will be prompted to add a new chamber. Click Yes.



Step 4: When prompted to add a new test, click Yes.

Step 5: The Add New Test window will appear. You must enter the appropriate information in all boxes with the exception of the Test Description box, which is optional. Once you have filled out the text boxes, click Add.

NOTE: If a value is entered incorrectly, it can be changed later in the Setup window. The Setup window is discussed in Section 7.3 Configuring Test Parameters.

Chamber Serial Number The serial number of the test chamber (cannot be edited)

Test Name Enter a name for the test (up to 17 characters).

Test Description (optional) If desired, enter a description for the test (up to 111 characters long).

Film Thickness Enter the thickness of the film in either MIL or microns. If the thickness of the film is unknown, enter “1”.

Volume Enter the volume of the sensing well in mL. This can be found on a label located on the top exterior of the permeation chamber.

Oxygen Value Enter the oxygen concentration in the driving well. If you are using ambient oxygen, enter 20.9.

Step 6: You will be prompted to verify the O2xyDot® calibration factors. If the calibration factors that appear on the screen are the correct calibration factors for the O2xyDot® in the permeation chamber, click Yes and go to Step 8. If the calibration factors are not correct, click No and continue to Step 7.



Step 7: If you clicked No at the calibration prompt, a window will appear allowing you to enter the proper dA and dB values for the O2xyDot®. You will be required to enter the values and then confirm the values. When finished, click OK.

IMPORTANT: Be certain to enter the dA and dB values properly. Be mindful of decimal places and “minus” signs (-).

Step 8: The new test has been created. You will be returned to the Oxygen Permeation Tests screen. The name of the test that was just created will now appear in the Oxygen Permeation Test Name box.

7.3 Configuring Test Parameters

In this section you will learn about the features in the Setup window and how to change parameters related to a test. You may change the test setup at any time while a test is active. Once a test is ended (closed) you may not change the setup for the test.

• The following list gives some of the items that can be changed in the Setup window.

• OTR reporting units

• Sensing well volume

• Driving well oxygen concentration

• Film thickness

NOTE: If you have already recorded data for a test, changing values in the Setup window will change the current OTR calculations. You will notice that the OTR result in the OTR screen will be recalculated after applying changes.

Steps to Configuring Test Parameters

Step 1: With the OxySense Gen III software running, click on the Film Permeation tab.

You will see the Oxygen Permeation Tests screen. If the test you wish to setup is already open, you may click the Setup button and skip to Step 4. If the test is not already open, open the test by first clicking on the Browse Active button.



Step 2: After clicking the Browse Active button, you will see the Browse Active window. Locate the test you wish to open, then select the test by clicking on it, and then click the Open button.

Step 3: You will see the OTR screen. Click the Setup button

Step 4: The Setup Password window will appear. Enter the password oxysense and click OK.



Step 5: You will see the Setup window. The following table gives a list of items that can be configured in the Setup window.

You do not have to make changes to the values in the Setup screen if they are correct. If you made changes to the test setup, click OK. Otherwise, you may click Cancel.

Default/Instrument Pressure Options

Allows you to select whether to use the instrument’s internal pressure sensor (Instrument Pressure) or whether to use a user- defined pressure (Default Pressure) in oxygen concentration calculations.

NOTE: The Default Pressure feature is provided for use in special applications. Always use Instrument Pressure unless your application uses a specific, known pressure.

Default Pressure Box The default pressure value in mbar (discussed above)

Film Thickness The thickness of the film in either MIL or microns. If the thickness of the film is unknown, enter “1”.

Volume The volume of the sensing well in mL. This can be found on a label located on the top, exterior of the permeation chamber.

Area

The cross-sectional surface area of the sensing well in cm2.

NOTE: The Area feature is provided for use in special applications. Always use the default value of 16.76 unless your application uses a specific, known area.

Oxygen Value The oxygen concentration in the driving well. If you are using ambient oxygen, enter 20.8 (no ‘%’ sign).

View By

Allows you to select the units of measurement for the oxygen concentrations displayed in the Display Area on the OTR screen.

NOTE: Changing the oxygen concentration unit will not affect the OTR calculations.

View OTR By Allows you to select the reporting unit for the OTR result.



7.4 Acquiring Data

After preparing the permeation chamber and creating a test in the Gen III software, you are now ready to begin recording data. When acquiring data, it is important to understand the principles of dynamic accumulation and the way the rate of permeation is determined. It is important to note that the number of data points captured for a test and the time that elapses between capturing data points will vary from film to film.

In this section you will learn how to capture data, how to determine the time interval between data points, and how to use the timer feature.

Steps to Acquiring Data

Step 1: Open the test you wish to add data to. With the OxySense Gen III software running, click on the Film Permeation tab.

You will see the Oxygen Permeation Tests screen. If the test you wish to setup is already open, you may click the Setup button and skip to Step 5. If the test is not already open, open the test by first clicking on the Browse Active button.

Step 2: After clicking the Browse Active button, you will see the Browse Active window. Locate the test you wish to open, then select the test by clicking on it, and then click the Open button. This will open the OTR Screen.

Step 3: Place the reading pen in to the reading pen well in the top of the permeation chamber being used for the test. Ensure that the alignment marker on the chamber is aligned with the alignment marker on the reading pen.



Step 4: Click Capture in the OTR screen to take your first reading. Notice that an oxygen concentration value has appeared in the Oxygen Log in the Display Area (displays the Oxygen Log by default).

The OTR will result will remain at 0.0000 until you record a second data point.

7.4.1 Time Intervals

The first data point recorded is referred to as Time 0. This is the initial oxygen value at the beginning of the test. This value is used as the starting point for the calculation of the rate of permeation.

In order to ensure that the calculated OTR results are reliable, it is important to take data points at time intervals that allow for a significant increase in oxygen concentrations between data points. In other words, you must ensure that the changes in oxygen concentrations between data points are large enough that the there is a clear distinction between the oxygen concentrations from one data point to the next. The time interval between data points will depend on the barrier of the film (whether it is high or low) and the oxygen concentration in the driving well.

The following are the rules-of-thumb that should be applied when performing a film permeation test by dynamic accumulation using an OxySense 5250i instrument and an OxySense Permeation Chamber:

• The absolute oxygen concentration difference between data points should be 0.15% or

greater.

• The oxygen concentration in the sensing well should not exceed 10%.

• You should take a minimum of five data points.

The following table gives the suggested time intervals between data points for films of known OTR:



20.8% Oxygen In Driving Well1

100% Oxygen In Driving Well1

OTR (mL/m2/day)

Estimated Time for Test

Completion2

Suggested Time Between Each Measurement3

Estimated Time for Test

Completion2

Suggested Time Between Each Measurement3

0.5 120 days 30 days 28 days 7 days

1 72 days 18 days 16 days 4 days

5 16 days 4 days 4 days 1 day

10 12 days 3 days 2 days 12 hrs

20 8 days 2 day 1 day 6 hrs

50 4 days 1 day 8 hrs 2 hrs

75 2 day 12 hrs 6 hrs 90 mins

100 1 day 4 hrs 4 hrs 60 mins

200 8 hrs 2 hrs 2 hrs 30 mins

500 4 hrs 1 hr 48 mins 12 mins 120.8% oxygen is considered to be the concentration of oxygen in the atmosphere (i.e. air). 100% oxygen is pure oxygen. Contact your local specialty gas vendor to inquire about procuring a cylinder of pure oxygen.

2Test lengths are estimated and given here to illustrate that a test will be longer or shorter depending on the permeability of the film. Estimates are based upon the amount of time in which to acquire five data points at the suggested measurement interval. Actual results may vary.

3Suggested measurement intervals are given as examples of the amount of time to wait between measurements to allow for a significant accumulation of oxygen between data points. Allowing for a significant amount of oxygen to accumulate between readings reduces the effects of measurement errors on the final test result.

7.4.2 Frequently Asked Questions about Time Intervals Q: Am I required to use the time intervals in the table?

A: The time interval values given in the table above are suggested minimum amounts of time that you should allow to elapse between data points. You are not required to take a data point at these intervals. These are provided for reference purposes only.

Q: Does there have to be the same amount of time between each data point?

A: The time intervals between data points do not have to be equal. In other words, you may take a second data point 24 hours after the first and a third data point 72 hours after the second. The Gen III software will calculate the rate of permeation based on the actual amount of time elapsed between data points, negating the need to capture data at discrete time intervals.

Q: Do I have to come in on my day off to take data?

A: Your organization may have staffing considerations that make it difficult to capture data during evenings, on weekends, and on holidays. If you are running a test and cannot take a data

point during off hours, simply take a data point at the next available opportunity. As stated above, the time between data points does not have to be equal.



Q: If I don’t know the OTR of my film, how do I know how much time to wait before taking the next data point?

A: If an estimated or expected OTR of a film is unknown, the time interval must be determined by data monitoring. This will mean capturing data at short intervals at first, then at longer intervals until the oxygen concentration has increased by 0.10%. The amount of time elapsed between the first data point (Time 0) and the data point when the oxygen concentration is 0.10% or greater is the time interval you should apply to the remainder of the test.

Q: How will I know if I am taking too many or not enough data points?

A: There is no maximum to the number of data points you may take as long as the concentration in the sensing well does not exceed 9% as a rule of thumb. You will find it beneficial to limit the number of data that you take when you begin working with data.

The absolute minimum number of data points that you must take is five. This ensures the validity of the applied statistics used to calculate the rate of permeation.

7.4.3 Using the Timer Feature

If you wish to take data points at a specific time interval you may find it useful to use the Timer feature in the Gen III software. The timer allows you to configure the instrument for automated data acquisition. This allows you to run a permeation test without having to visit the instrument several times throughout the test to take data manually.

NOTE: If you are running simultaneous tests in multiple permeation chambers, or if the instrument is being used for many purposes by multiple users, it may not be appropriate to use the timer. In order for the timer to be useful, the instrument’s reading pen must be left in the reading pen well of a permeation chamber while the timer is running.

Steps to Using the Timer

Step 1: Open the test you wish to add data to.

Step 2: Determine the desired timer interval. The timer can only be set to take readings in seconds and minutes. If you wish to set the timer to take readings in hours or days, you will need to convert the hours or days to minutes.

EXAMPLE: if you wish to capture a data point once every 24 hours, you will set the timer interval to 1440 minutes. Enter 1440 in the Timer Interval Box and then select minutes from the Timer Interval drop-down box.



Step 3: Before starting the timer, it is best to display the OTR Graph while the timer is running. This allows you to monitor the stability of the rate of permeation. Click on the select button next to OTR in the Graph row of display options.

Step 4: Click the Timer button. You will see that the red indicter next to the timer button is now green and that the timer countdown is now displayed at the bottom of the screen.

To stop the timer, simply click on the Timer button a second time.



8.0 Data Analysis

In order to determine the progress of the test and when the test has ended, you will need to learn how to interpret the Data Quality Indicators available to you in the OTR screen. The four main data quality indicators are listed below.

• The OTR Graph

• The oxygen graph

• The R2 value

Each of these tools is explained in further detail in this section. You will also learn how to work with data. In order to obtain a reliable OTR result, you may have to eliminate certain data points. Later in this section you will learn how to determine whether or not it is necessary to eliminate data points and which data points you may eliminate.

IMPORTANT: This section discusses the deletion of data from the table of oxygen concentration data points. You may only delete data points when there is a technical justification for doing so.

8.1 Data Quality Indicators

The data quality indicators listed above can be used in conjunction to determine the progress of the permeation test. Before ending a test and obtaining a final result, the following three criteria should be met:

• The OTR graph must appear to plateau

• The oxygen graph should appear to be linear.

• The R2 value must be 0.990 or greater.

8.1.1 The OTR Graph

The OTR graph depicts the changing rate in permeation over time. The OTR graph will rise quickly and then plateau. When the graph plateaus, or “flat-lines,” this is an indication that the permeation rate is stable and that the test may be ended.

The OTR graph is displayed by clicking on the OTR option in the Graph row of the Display Options. Be certain that the proper scale is selected for the

X-Axis. You may find that it is necessary to Figure 8-1: The OTR Graph

!



choose a scale with smaller increments than the time interval. For example, if the data points were captured every 3 hours, set the X-Axis to minutes. Select the X-Axis scale by clicking the desired selection box from the X-Axis options.

8.1.2 The Oxygen Graph

The oxygen graph depicts the oxygen concentration over time. The oxygen graph can be used to indicate whether or not the rate of oxygen accumulation is stable. Oxygen concentration values typically rise in a linear fashion when the permeation rate is stable.

The oxygen graph is displayed by clicking on the Oxygen option in the Graph row of the Display Options. Be certain that the proper scale is selected for the X-Axis. You may find that it is necessary to choose a scale with smaller increments than the time interval. For

example, if the data points were captured every 3 hours, set the X-Axis to minutes. Select the X-Axis scale by clicking the desired selection box from the X-Axis options.

8.1.3 The R2 Value

R2 is the coefficient of determination and indicates the “goodness of fit” of the data points captured for the test. R2 must be 0.990 or greater.

Figure 8-2: The Oxygen Graph

R2 0.995841Figure 8-3: The R2 Value



9.0 Data Interpretation

When performing OTR by DA using OxySense instrumentation, you will find that certain materials, especially those that exhibit a relatively high barrier, will not begin to transmit oxygen immediately. This is due to the physical properties of the film. At the beginning of a test, oxygen ingress in to the sensing well has not yet occurred. As molecules of oxygen begin to permeate through the film and eventually migrate in to the sensing well, the oxygen concentration in the sensing well will increase. However, this may not occur for several hours or even days. Additionally, the amount of oxygen that begins to make its way across the film early on may not be representative of the transmission across the entire cross-section of film. You may observe a very small change in oxygen measurements at first that grow increasingly larger until stability is achieved. This is due to variability in gas exchange throughout the cross-section.

9.1 The Conditioning Phase

The period of the test prior to stabilization of gas exchange is referred to as the conditioning phase, where, oxygen ingress has yet to be observed or is observed to be increasing. After the film is conditioned, the test enters the permeation phase, where, observable oxygen ingress has stabilized.

The chart given below shows data acquired over the course of an OTR test. Data points take prior to Day 4 were obtained during the conditioning phase. Data points acquired on Day 4 and beyond were obtained during the permeation phase.

Figure 9-1: Conditioning & Permeation Phases

Oxygen Concentration

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 2 4 6 8 10Days

Oxy

gen

(%)

Data Points

Permeation PhaseConditioning Phase



9.2 Rejecting Data

When data does not conform to a predetermined technical criterion, it may be rejected so long as there is a valid technical justification for doing so. When performing OTR by DA and capturing data to the OxySense® Gen III software, it may be necessary to reject data points from the beginning of the data table or the end of the data table and only under the following conditions:

1. Data points toward the beginning of the data set were obtained prior to oxygeningress stability (conditioning phase) and are giving uneven weighting to thecalculated OTR value.

2. Data points taken toward the end of the test are giving uneven weighting to thecalculated OTR value.

IMPORTANT: You may not reject data from the middle of a data set in an attempt to achieve a higher R2 value. This is commonly referred to as “cherry-picking” and is forbidden.

9.2.1 Gen III Software

The current method for rejecting data in the Gen III software is to delete data points. The following instructions explain how to delete a data point.

Step 1: Open the test you wish to reject data from and click to view the Oxygen Log.

Step 2: Select the data point which you wish to reject.

!



Step 3: Click the Delete Data Point button. You will be prompted to confirm the deletion. Click Yes to confirm.

IMPORTANT: The process of deleting a data point is irreversible. You may wish to back up a copy of the Gen III database prior to rejecting data.

Step 4: After deletion, the data log will be updated. The second data point is now the first and the OTR value is recalculated.

!



10.0 Troubleshooting

The following examples illustrate scenarios that one may observe throughout the course of a package permeation test. An explanation of the observations and recommended solutions are provided:

Scenario 1

Observation: The OTR is negative, or the OTR keeps going up and down.

Common Reason:

The test is in the conditioning phase.

Common Solution:

Continue to take data. Eventually the test will enter the permeation phase.

Refer To: Section 9.1 The Conditioning Phase

Scenario 2

Observation: The OTR continues to rise without stabilizing.

Common Reason:

Data taken during the conditioning phase is giving weight to the calculated OTR.

Common Solution:

Continue to take data until the OTR stabilizes, or reject data points taken during the conditioning phase.

Refer To: Section 9.1 The Conditioning Phase & Section 9.2 Rejecting Data

Scenario 3

Observation: The OTR stabilized and began to rise again.

Common Reason:

The initial increase in oxygen concentration occurred during the conditioning phase and is attributable to out-gassing of the film. This can be significant for films 100 µm or thicker.

Common Solution:

Continue to take data until the OTR stabilizes, or reject data points taken during the conditioning phase.

Refer To: Section 9.1 The Conditioning Phase & Section 9.2 Rejecting Data



11.0 Technical Support

For technical support, contact Industrial Physics Product Integrity

Email:

Phone:

[email protected]

+1 (978) 772.2048



Permeation Chamber User’s Manual Page A-1

Appendix A: O2xyDot® Calibration

The permeation chamber comes with an O2xyDot installed on the interior portion of the sensing well opposite the chamber’s reading window. The O2xyDot® is used to measure the oxygen concentration in the chamber. If this is the first time the chamber has been used for a permeation test, you must calibrate the O2xyDot® to your instrument.

This section gives step-by-step instructions on how to calibrate the O2xyDot for first-time use. If this is not the first time the chamber has been used, and a calibration has already been performed, you may skip this section and go to section 6.2 Purging the Sensing Well.

In the following steps you will learn how to perform a two-point calibration of the O2xyDot using a high and a low calibration points. In this example, we will use the concentration of atmospheric oxygen (20.8%) as the high calibration point and 0% oxygen as the low calibration point. For the high calibration point, the chamber is left open to the atmosphere and the air in your operating environment is used as the high-level calibration gas.

Note: Depending on the requirements of your organization’s Quality Assurance program, you may be required to use a certified calibration gas. The certified calibration gas for the high calibration point should be made of a balance of oxygen and nitrogen with a certified concentration of oxygen by volume. This is sometimes referred to as certified air. Cylinders of certified air can normally be purchased from a gas specialty vendor such as a welding supply retailer.

Calibration Steps:

Step 1: Be sure that there is film in the chamber. If you have not placed film in the chamber, please go to Section 6.1 Placing Film in the Chamber

Step 2: Turn on the OxySense 5250i instrument and allow the system to warm up for 30 minutes.

Step 3: If it has not already running, launch the OxySense Gen III Software.



Step 4: Perform the background correction when prompted. You may use the O2xyDot® in the permeation chamber to perform the second step of the back ground correction.

Step 5: Obtain the High Calibration Point:

Ensure that both of the valves on the top of the chamber are fully open.

Ensure that the reading pen is inserted properly in the top of the chamber. Ensure that the alignment marker on the chamber is aligned with the alignment marker on the reading pen.

Click on the Calibration tab in the Gen III software.

Enter the concentration of the high calibration point in the High box under Self Calibration. For atmospheric oxygen (i.e. air), the concentration is 20.8%. Simply enter 20.8.

Click the Get High button located under Self Calibration. The instrument will take a reading from the O2xyDot® in the permeation chamber. Note that when the reading is complete, the Ratio box for the high calibration point is now populated. This is the raw instrument signal information associated with the high calibration point (20.8% in this scenario).



Step 6: Obtain the Low Calibration Point:

Ensure that both of the valves on the top of the chamber are fully open.

Ensure that the reading pen is inserted properly in the top of the chamber. Ensure that the alignment marker on the chamber is aligned with the alignment marker on the reading pen.

Connect the regulator of a nitrogen cylinder (99.99+% purity) to the inlet of the flow meter using a length of ¼” gas tubing and tubing connectors with ferrules.

Open the tank valve of the certified gas cylinder and any check valves that may be installed on your regulator or flow meter.

The flow of gas will begin. Set the flow meter to a rate of 0.05 L/min (0.1 SCFH).

Allow the gas to flow for 30 seconds to flush the connected tubing.

IMPORTANT: Flow rate must not exceed 0.1 L/min (0.2 SCFH). Flow rates greater then 0.1 L/min can cause damage to the film.

Set the timer on the instrument to take a reading at 10 second intervals. To do so, click the Logging/Timer tab in the Gen III software, then enter 10 in the Measurement Interval box, and then select Seconds from the Measurement Interval drop-down box. Click the Timer button located in the bottom right-hand corner of the screen. The instrument will begin taking automatic readings every 10 seconds.

1.0 .8

.6

.4

.2

.1 0.1 SCFH !



(Step 6 cont’d)

Connect the outlet of the flow meter to the inlet valve of the top half of the permeation chamber using a length of ¼” gas tubing and tubing connectors with ferrules.

Monitor the oxygen concentration displayed on the instrument.

Allow the gas to flow until the oxygen concentration readings have stabilized.

Turn off the timer in the Gen III software by clicking the Timer button located in the bottom, right-hand corner of the screen.

Click on the Calibration tab in the Gen III software.

Ensure that the appropriate oxygen concentration is entered in the High box under Self Calibration. For high-purity nitrogen, the concentration is 0%. Simply enter 0.

Click the Get Low button located under Self Calibration. The instrument will take a reading from the O2xyDot® in the permeation chamber. Note that when the reading is complete, the Ratio box for the low calibration point is now populated. This is the raw instrument signal information associated with the low calibration point.



Step 7: Close the valves to the sensing well in the following sequence: Close the inlet valve first and then quickly close the outlet valve.

IMPORTANT: You must close the inlet valve and then the outlet valve in that order. If you close the outlet valve before the inlet valve, the sensing well will pressurize causing the film in the chamber to distort, bulge and possible rupture.

Step 8: Close the tank valve on the nitrogen cylinder and any check valves between the cylinder’s regulator and the flow meter.

Disconnect the tubing from the permeation chamber’s inlet.

Step 9: Click the Calculate New dA/dB button under Self Calibration. Note that the dA and dB boxes located under New under Calculated dA/dB are now populated.

Step 10: Click the Save Calculated dA/dB button located under Calculated dA/dB. Note that the dA and dB boxes located under Current under Calculated are now populated.

Step 11: Record the new dA and dB values in a safe location such as a laboratory notebook. Be sure to note the permeation chamber’s serial number and the date.

1

2



Step 12: Proceed to one of the following sections:

If you plan to use ambient oxygen in the driving well, proceed to section 7.0

If you plan to purge the driving well with 100% oxygen, proceed to Section 6.3


Permeation Chamber User’s Manual Page B-1

Appendix B: Basic Principles of Film OTR by Dynamic Accumulation

Oxygen Transmission Rate (OTR) is the rate at which a unit volume of oxygen gas permeates through a unit area of film per unit time. Film OTR is commonly expressed in milliliters per square-meter per day (mL/m2/day) or milliliters per 100 square-inches per day (mL/100in2/day).

NOTE: 1 mL is equal to 1 cubic centimeter (cc). Hence, 1 mL/m2/day = 1 cc/m2/day and 1 mL/100in2/day = 1 cc/100in2/day

OxySense utilizes the method of dynamic accumulation (DA) for OTR determination where the volume of oxygen that permeates through the film accumulates in the sensing well of the permeation chamber. As oxygen crosses the film and accumulates in the sensing well, the concentration of oxygen in the sensing well increases. The oxygen concentration in the sensing well is monitored non-invasively by using an OxySense® 5000 Series instrument to read the O2xyDot® inside the sensing well. The OxySense® 5000 Series instrument calculates the OTR based on the increasing amount of oxygen gas in the sensing well over time using the following equation:

AVKOTR ×= (Equation B-1)

Where:

OTR = oxygen transmission rate (mL/m2/day or mL/100in2/day) K = Coefficient of determination (days-1) V = Volume of sensing well (mL) A = Surface area of the film (m2 or 100in2)

NOTE: The surface area of the film used in this equation is the area that is exposed to the sensing well and is equal to the cross-sectional area of the sensing well. In an OxySense® Permeation Chamber, the surface area is 0.001676 m2.

The coefficient of determination for the film is obtained via the least-squares regression of the accomplished oxygen rate (AOR), as described by Abdellatief and Welt, over time in days:

( )∑ ∑

∑ ∑ ∑

−

⋅−⋅

=

nt

t

ntAOR

tAORK 2

2

(Equation B-2)

Where: K = Coefficient of determination (days-1) AOR = Accomplished oxygen rate (unitless)

t = Time (days)


Permeation Chamber User’s Manual Page B-2

The calculated AOR is defined as the exponent that gives the quotient of volume of accumulated oxygen over the maximum potential accumulated volume and is both time and barrier dependent.

[ ] [ ][ ] [ ] ⎟⎟

⎠

⎞⎜⎜⎝

⎛

−−

−=02max2

022lnPOPO

POPOAOR n (Equation B-3)

Where: AOR = Accomplished oxygen rate (unitless) [PO2]n = Accumulated oxygen at time n [PO2]0 = Accumulated oxygen at time 0 [PO2]max = Maximum potential accumulated oxygen

EX) An OTR test is run in a permeation chamber with a sensing well volume of 7 mL and surface area of 0.001676 m2. K is 0.01 per day. The OTR is calculated as follows:

daymmLOTR

m

mLday

OTR

AVKOTR

2

2

42

001676.0

701.0

=

×⎟⎟⎠

⎞⎜⎜⎝

⎛

=

×=

(Equation B-4)

In order to determine the OTR of a film by DA, you must be able to measure the increase in oxygen concentration over time. Therefore the oxygen concentration in the sensing well must be significantly lower than the oxygen concentration in the driving well. In order to ensure that this is the case, the sensing well must be purged with an inert gas (nitrogen) so that the initial oxygen concentration in the sensing well is 0%. The driving well may be left open to the atmosphere (approximately 20.8% oxygen) or it may be purged with 100% oxygen to accelerate the test (optional).

NOTE: The initial concentration in the sensing is not required to be exactly 0% under DA. You may obtain a valid OTR even when the oxygen concentration in the sensing well is nominally greater than zero at the beginning of the test.

B.1 References

Abdellatief, A. and Welt B. A. (2012), Comparison of New Dynamic Accumulation Method for Measuring Oxygen Transmission Rate of Packaging against the Steady-State Method Described by ASTM D3985. Packaging Technology and Science. doi: 10.1002/pts.1974


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