ASTM F2476-05
(Test Method)Test Method for the Determination of Carbon Dioxide Gas Transmission Rate (Co 2TR) Through Barrier Materials Using An Infrared Detecto
Test Method for the Determination of Carbon Dioxide Gas Transmission Rate (Co<sub> 2</sub>TR) Through Barrier Materials Using An Infrared Detecto
SIGNIFICANCE AND USE
Carbon dioxide gas transmission rate (CO2TR) is an important determinant of the packaging protection afforded by barrier materials. It is not, however, the sole determinant, and additional tests, based on experience, must be used to correlate packaging performance with CO2TR. It is suitable as a referee method of testing, provided that purchaser and seller have agreed on sampling procedures, standardization procedures, test conditions and acceptance criteria.
SCOPE
1.1 This method covers a procedure for determination of the steady-state rate of transmission of carbon dioxide gas through plastics in the form of film, sheeting, laminates, coextrusions, or plastic-coated papers or fabrics. It provides for the determination of (1) carbon dioxide gas transmission rate (CO2TR), (2) the permeance of the film to carbon dioxide gas (PCO2) , and (3) carbon dioxide permeability coefficient (P"CO2) in the case of homogeneous materials.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: F2476 − 05
StandardTest Method for
the Determination of Carbon Dioxide Gas Transmission Rate
(Co TR) Through Barrier Materials Using An Infrared
Detector
This standard is issued under the fixed designation F2476; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope of carbon dioxide permeability is the mol/m·s·Pa. The test
conditions (see 3.1.3) must be stated.
1.1 This method covers a procedure for determination of the
3.1.2 Carbon dioxide permeance (P’CO ) —the ratio of the
steady-state rate of transmission of carbon dioxide gas through
CO TR to the difference between the partial pressure of CO
plastics in the form of film, sheeting, laminates, coextrusions,
2 2
on the two sides of the film. The SI unit of permeance is the
or plastic-coated papers or fabrics. It provides for the determi-
mol/(m ·s·Pa). The test conditions (see 3.1.3) must be stated.
nation of (1) carbon dioxide gas transmission rate (CO TR),
(2) the permeance of the film to carbon dioxide gas (P’CO),
2 3.1.3 Carbon dioxide transmission rate (CO TR) —The
and (3) carbon dioxide permeability coefficient (P”CO )inthe
quantity of carbon dioxide gas passing through a unit area of
case of homogeneous materials.
the parallel surfaces of a plastic film per unit time under the
conditions of the test. The SI unit of transmission rate is the
1.2 This standard does not purport to address all of the
mol/(m ·s). The test conditions, including temperature and
safety concerns, if any, associated with its use. It is the
carbon dioxide partial pressure on both sides of the film, must
responsibility of the user of this standard to establish appro-
be stated.
priate safety and health practices and determine the applica-
3.1.3.1 Discussion—A commonly used metric unit of
bility of regulatory limitations prior to use.
CO TR is the cc(STP)/(m ·day) at one atmosphere driving
2. Referenced Documents
force pressure differential where: 1 cc(STP) is 44.62 µmol. 1
atm is 0.1013 MPa. and one day is 86.4 x 10 s. CO TR in SI
2.1 ASTM Standards:
units is obtained by multiplying the value in metric units by
D1898 Practice for Sampling of Plastics (Withdrawn 1998)
-10 3
5.164 x 10 or the value in inch-pound units (cm (STP)]/100
E691 Practice for Conducting an Interlaboratory Study to
2 -9
in ·day) by 8.004 x 10 .
Determine the Precision of a Test Method
4. Summary of Test Method
3. Terminology
4.1 The carbon dioxide gas transmission rate is determined
3.1 Definitions:
after the sample has equilibrated in a dry-test environment. In
3.1.1 Carbon dioxide permeability coeffıcient (P”CO )—the
this context, a “dry” environment is considered to be one in
product of the permeance and the thickness of film. The
which the relative humidity is less than 1 %.
permeability is meaningful only for homogeneous materials, in
which case it is a property characteristic of the bulk material.
4.2 The specimen is mounted as a sealed semi-barrier
This quantity should not be used unless the relationship
between two chambers at ambient atmospheric pressure. One
between thickness and permeance has been verified on tests
chamber is slowly purged by a stream of nitrogen and the other
using several different thicknesses of the material. The SI unit
chamberwithcarbondioxide.Ascarbondioxidegaspermeates
through the film into the nitrogen carrier gas, it is transported
to an infrared detector where an electrical output is produced
This test method is under jurisdiction of ASTM Committee F02 on Flexible
whose magnitude is proportional to the amount of CO flowing
Barrier Packaging and is the direct responsibility of Subcommittee F02.10 on
into the detector per unit of time.
Permeation.
Current edition approved Jan. 3, 2006. Published May 2005. DOI: 10.1520/
F2476-05.
5. Significance and Use
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1 Carbon dioxide gas transmission rate (CO TR) is an
Standards volume information, refer to the standard’s Document Summary page on
important determinant of the packaging protection afforded by
the ASTM website.
barrier materials. It is not, however, the sole determinant, and
The last approved version of this historical standard is referenced on
www.astm.org. additional tests, based on experience, must be used to correlate
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2476 − 05
packaging performance with CO TR. It is suitable as a referee 6.1.1.3 Diffusion Cell Pneumatic Fittings—each half of the
method of testing, provided that purchaser and seller have diffusion cell shall incorporate suitable fittings for the intro-
agreed on sampling procedures, standardization procedures, duction and exhaust of gases without significant loss or
test conditions and acceptance criteria. leakage.
6.1.1.4 It is desirable to thermostatically control the diffu-
6. Apparatus
sion cell. Because the transmission rate is a function of
temperature, it shall be controlled to within 6 0.1°C.
6.1 Carbon Dioxide Gas Transmission Apparatus, as dia-
6.1.1.5 Experience has shown that arrangements using mul-
grammed in Fig. 1 or Fig. 2, with the following:
tiple diffusion cells are a practical way to increase the number
6.1.1 Diffusion Cell—shall consist of two metal halves,
of measurements that can be obtained from an infrared sensor.
which, when closed upon the test specimen, will accurately
A valving manifold connects the carrier gas side of each
define a circular area.Atypical acceptable diffusion cell area is
50 cm .The volume enclosed by each cell half, when clamped, individual diffusion cell to the sensor in a predetermined
pattern. Carrier gas is continually purging the carrier gas side
in not critical: it should be small enough to allow for rapid gas
exchange, but not so small that an unsupported film that of those cells that are not connected to the sensor. Either test
gasorcarriergas,asisappropriate,purgesthetestgaschamber
happens to sag or bulge will contact the top or bottom of the
of any individual cell.
cell.
6.1.2 Flowmeter—a means shall be provided to establish
6.1.1.1 O-Ring Groove—an appropriately sized groove, ma-
and maintain test gas and carrier gas flows.An operating range
chined into the CO (or test gas) side of the diffusion cell,
in the order of 5 to 100 ml/min for CO and up to 300 ml/min
retains an elastomer O-ring. The test area is considered to be
for N .
that area established by the inside contact diameter of the
6.1.3 Flow Switching Valves—needed to perform the tasks
compressed O-ring when the diffusion cell is clamped shut
of (1) purging, (2) accumulating, if needed, for static or
against the test specimen. The area, A, can be obtained by
dynamic testing methods, and (3) maintaining flow for con-
measuring the inside diameter of the imprint left by the O-ring
tinuous flow methods.
on the specimen after it has been removed from the diffusion
6.1.4 Infrared sensor—a 4.3 µm infrared filter to measure
cell.
the quantity of CO in the carrier gas going to the sensor.
6.1.1.2 Thenitrogen(orcarriergas)sideofthediffusioncell
shall have a flat raised rim. Since this rim is a critical sealing
NOTE 1—The infrared sensor is not an absolute measuring device.
surface against which the test specimen is pressed, it shall be
Therefore, some standard has to be used to establish a point of reference.
smooth and flat, without radial scratches. A means of providing a known quantity of CO has been used and has
FIG. 1 A practical arrangement of components for the measurement of carbon dioxide transmission rate using a non-computerized
system
F2476 − 05
FIG. 2 A practical arrangement of components for the measurement of carbon dioxide transmission rate using a computerized system
been found satisfactory for this application. The use of a calibrated valve
7.3 Sealing Grease—a high-viscosity silicone stopcock
enables the system to establish the point of reference against which the
grease or high-vacuum grease for sealing the specimen film in
unknown film is compared or the system may also be calibrated with a
the diffusion cell.
reference film .
7.4 Aluminum Foil Reference Blank—The term “reference
6.1.5 Recording device—a strip chart recorder or, if the
blank” or “blocking plate” refers to a non-transmitting, zero
system is computer- controlled, a monitor and a printer have
reference aluminum foil sheet. Used in some instruments to
been found to be adequate.
establish system zero prior to testing film specimens.
7. Reagents and Materials
8. Precautions
7.1 Nitrogen gas—grade need not be higher than “High
8.1 Temperature is a critical parameter affecting the mea-
Purity” or “Extra Dry,” which is readily available in most of
surement of CO TR. Careful temperature control will help to
the principle cities at low cost. A regulator with auxiliary
minimize variations due to temperature fluctuations. During
metering valve and outlet fittings for ⁄8 in. tubing should be
testing, the temperature shall be maintained within 6 0.1°C.
used.
The average temperature and the range of temperatures found
during a test shall both be reported. Accurate temperature
7.2 Carbon Dioxide gas—a carbon dioxide concentration of
control is easier to maintain if the instrument is placed in a
99.9 % or greater is suitable for this application.
temperature-controlled environment.
8.2 The sensor will require time to stabilize to a low reading
The sole source of supply of the reference material known to the committee at
characteristic of a good CO barrier after it has been used to
this time is MOCON, 7500 Boone Ave. North, Minneapolis, MN 55428. If you are
test a high transmission barrier. For this reason, materials of
aware of alternative suppliers, please provide this information to ASTM Interna-
comparable gas transmission qualities should be tested to-
tional Headquarters. Your comments will receive careful consideration at a meeting
of the responsible technical committee , which you may attend. gether.
...
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