ASTM D6701-01
(Test Method)Standard Test Method for Determining Water Vapor Transmission Rates Through Nonwoven and Plastic Barriers (Withdrawn 2008)
Standard Test Method for Determining Water Vapor Transmission Rates Through Nonwoven and Plastic Barriers (Withdrawn 2008)
SIGNIFICANCE AND USE
The purpose of this test method is to obtain values for the water vapor transmission rate of barrier materials.
Water vapor transmission rate is an important property of materials and can be related to shelf life; product stability, breath-ability, and wearing comfort.
Data from this test method is suitable as a referee method of testing, provided that the purchaser and seller have agreed on sampling procedures, test conditions, and acceptance criteria.
SCOPE
1.1 This test method covers a procedure for determining the rate of water vapor transmission ranging between 500 to 100,000 g/m 2day through nonwoven and plastic barrier materials. The method is applicable to films, barriers consisting of single or multilayer synthetic or natural polymers, nonwoven fabric, and nonwoven fabrics coated with films up to 3 mm (0.1 in.) in thickness.
1.2 This test method provides for the determination of (1) water vapor transmission rate (WVTR), and (2) the permeance to water vapor.
1.3 The values stated in metric units are to be regarded as the standard. The acceptable units for water vapor transmission rate are usually g/m2day.
1.4 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.
WITHDRAWN RATIONALE
This test method covers a procedure for determining the rate of water vapor transmission ranging between 500 to 100,000 g/m2day through nonwoven and plastic barrier materials. The method is applicable to films, barriers consisting of single or multilayer synthetic or natural polymers, nonwoven fabric, and nonwoven fabrics coated with films up to 3 mm (0.1 in.) in thickness.
This test method is being withdrawn with no replacement because D13 no longer has the technical expertise to maintain.
Formerly under the jurisdiction of Committee D13 on Textiles, this test method was withdrawn in October 2008.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D6701–01
Standard Test Method for
Determining Water Vapor Transmission Rates Through
Nonwoven and Plastic Barriers
This standard is issued under the fixed designation D 6701; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers a procedure for determining the 3.1 Definitions:
rate of water vapor transmission ranging between 500 to 3.1.1 water vapor permeability coeffıcient, n—the ratio of
100,000 g/m day through nonwoven and plastic barrier mate- the permeance and the thickness.
rials. The method is applicable to films, barriers consisting of 3.1.1.1 Discussion—Thisquantityshouldnotbeusedunless
single or multilayer synthetic or natural polymers, nonwoven the relationship between thickness and permeance has been
fabric,andnonwovenfabricscoatedwithfilmsupto3mm(0.1 verified in tests using several thickness’ of the material. The
in.) in thickness. water vapor permeability is meaningful only for homogeneous
1.2 This test method provides for the determination of (1) materials, in which case it is a property characteristic of bulk
water vapor transmission rate (WVTR), and (2) the permeance material. An accepted unit of water vapor permeability is the
to water vapor. metric perm centimeter, or 1g per m per day per mm Hg-cm of
1.3 The values stated in metric units are to be regarded as thickness. The SI unit is the mol/m -s-Pa-mm.
the standard.The acceptable units for water vapor transmission 3.1.2 water vapor permeance, n—the ratio of a barrier’s
rate are usually g/m day. water vapor transmission rate to the vapor pressure difference
1.4 This standard does not purport to address all of the between the two surfaces.
safety concerns, if any, associated with its use. It is the 3.1.2.1 Discussion—An accepted unit of water vapor per-
responsibility of the user of this standard to establish appro- meance is the metric perm, or 1 g/m per day per mm Hg. The
priate safety and health practices and determine the applica- SI unit is the mol/m -s-Pa. Since the water vapor permeance of
bility of regulatory limitations prior to use. a specimen is generally a function of relative humidity and
temperature, therefore those conditions must be stated.
2. Referenced Documents
3.1.3 water vapor transmission rate (WVTR), n—the
2.1 ASTM Standards:
steady-state time rate of water vapor flow through unit area of
D 123 Terminology Relating to Textiles a specimen, normal to the surfaces under specific conditions of
D 1898 Practice for Sampling of Plastics
temperature and humidity at each surface.
D 4204 Practice for Preparing Plastic Film Specimens for a 3.1.3.1 Discussion—A common practice accepted unit of
4 2
Round-Robin Study
water vapor transmission rate is metric g/m per day. The test
D 5729 Test Methods for Thickness of Nonwoven fabrics conditions of relative humidity and temperature where the
E 691 Practice for Conducting an Interlaboratory Test Pro-
driving force is the difference in relative humidity across the
gram to Determine the Precision of Test Methods specimen must be stated.
F 1249 Test Method for Water Vapor Transmission Rate
4. Summary of Test Method
Through Plastic Film and Sheeting Using a Modulated
Infrared Sensor 4.1 Adry chamber, guard film, and a wet chamber make up
a diffusion cell in which the test film is sealed. A first test is
madeofthewatervaportransmissionrateoftheguardfilmand
This test method is under the jurisdiction ofASTM Committee D13 onTextiles
air gap between an evaporator assembly that generates 100 %
and is the direct responsibility of Subcommittee D13.90 on Executive.
relative humidity. A sensor produces an electrical signal, the
Current edition approved August 10, 2001. Published October 2001.
amplitude of which is proportional to water vapor concentra-
Annual Book of ASTM Standards, Vol 10.01.
Annual Book of ASTM Standards, Vol 08.03.
tion. The electrical signal is routed to a computer for process-
Annual Book of ASTM Standards, Vol 04.06.
ing. The computer calculates the transmission rate of the air
Annual Book of ASTM Standards, Vol 07.02.
gap and guard film and stores the value for further use. The
Annual Book of ASTM Standards, Vol 11.03.
Annual Book of ASTM Standards, Vol 15.09. barrier is then sealed in the test cell and the apparatus started
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6701–01
in the test mode. As before, the electrical signal representing cells are formed by metal halves which, when closed upon the
the water vapor is sent to the computer which then calculates test specimens, will accurately define a circular area for each.
the transmission rate of the combination of the air gap, the
Atypical acceptable diffusion cell area is 10 cm . The volume
guard film, and the test barrier. The computer then uses this enclosed by each cell half, when clamped, is not critical. It is
information to calculate the water vapor transmission rate of
desirable that the air gap between the water evaporator
the material being tested. The computer determines when the
assembly and the guard film be as small practical, but not so
measured results indicate that the specimens have reached
small that an unsupported film which sags or buckles will
equilibrium values and the testing is considered finished.
contact the evaporator assembly. The barrier under test should
be in intimate contact with the guard film. A depth of
5. Significance and Use
approximately 3.2 mm (0.125 in.) has been found to be
5.1 The purpose of this test method is to obtain values for
satisfactory for the carrier gas side of 10-cm cells.
the water vapor transmission rate of barrier materials.
6.1.1.1 Test Cell O-ring, an appropriately sized groove
5.2 Water vapor transmission rate is an important property
machined into the humid chamber side of the test cell that
of materials and can be related to shelf life; product stability,
retains a chlorprene O-ring. The test area is considered to be
breath-ability, and wearing comfort.
the area established by the inside contact diameter of the
5.3 Data from this test method is suitable as a referee
compressed O-ring when the test cell is clamped shut against
method of testing, provided that the purchaser and seller have
the test specimen.
agreedonsamplingprocedures,testconditions,andacceptance
6.1.1.2 Test Cell Sealing Surface, a flat rim around the dry
criteria.
side of the diffusion cell. This is a critical sealing surface
against which the test specimen is pressed; it shall be smooth
6. Apparatus
and without radial scratches.
6.1 This method utilizes water vapor transmission appara-
8 6.1.1.3 Test Cell Air Passages, two holes in the dry half of
tus comprised of the following:
the diffusion cell that pass carrier gas and water vapor to either
6.1.1 Test Cells, the apparatus has six test cells within two
exhaust ports or the sensor assembly. One cell at a time can be
assemblies. Fig. 1 shows a typical cell cross section. The six
connected to the sensor assembly by solenoid valves.
6.1.1.4 Test Cell Guard Film, a flat film that covers the
humid side of each cell. The film is a barrier that stills the air
The sole source of supply of the apparatus known to the committee at this time
in the gap between the water evaporator and the mounting
is Mocon, Inc., 7500 Boone Avenue North, Suite 111, Minneapolis, MN 55428. If
you are aware of any alternative suppliers, please provide this information toASTM planeofthespecimen.Theguardfilmisaveryhightransmitter
headquarters. Your comments will receive careful consideration at a meeting of the
of water vapor. Its transmission rate as well as that of the air
responsible technical committee, which you may attend. Mocon’s apparatus is
gap is accounted for in the apparatus’ measurements.
known as the Permatran-W model 100k.
FIG. 1 Typical Cell Cross Section
D6701–01
6.1.1.5 Water Vapor Sensor, a water vapor detector capable 8.2.4 Test Specimen Selection—Select test specimens as
of sensing 0 to 100 % relative humidity with sufficient accu- follows:
racy so the apparatus can determine transmission rates down to 8.2.4.1 Cut specimens representing a broad distribution
500 g/m per day. diagonally across the width of the laboratory-sampling unit.
6.1.1.6 Post Sensor Dryer, a no-maintenance dryer that 8.2.4.2 For fabric widths 125 mm (5 in.) or more take no
removes water vapor from the measurement gas stream after it specimen closer than 25 mm (1 in.) from the selvage edge.
passes through the water vapor sensor. 8.2.4.3 For fabric widths less than 125 mm (5 in.), use the
6.1.1.7 Mass Flowmeter, a means for regulating the flow of entire width for specimens.
dry air within an operating range of 0 to 200 cc/min. 8.2.4.4 Ensure specimens are free of folds, creases, or
6.1.1.8 Flow-Metering Valves, fine-metering valves capable wrinkles.Avoidgettingoil,water,grease,etc.onthespecimens
of controlling the dry-air flow rate to each test. when handling.
6.1.2 Computer System, a computer provides the main
9. Conditioning
control, calculating, and data storage device for the system.
9.1 No pre-conditioning is necessary before starting a test.
6.1.3 Temperature Control, Temperature of the test speci-
9.2 Any conditioning of the specimens to the water vapor
men is thermostatically controlled by a Thermo-Electric De-
vice (TED) attached to the apparatus that ensures good thermal driving force (differential relative humidity) and temperature is
carried out during the test within the test apparatus. In general,
contact. A thermistor sensor and an appropriate control circuit
willservetoregulatethetemperaturefrom20to50°Ctowithin these materials are high transmitters and the specimens do not
require a significant conditioning period; they reach equilib-
0.1°C.
6.1.4 Barometric Pressure Sensor, a sensor that measures rium in just a few examination periods. (Experience has shown
that individual test periods range from 2 to 10 minutes). The
the ambient barometric pressure so that variations are auto-
matically corrected in the calculations. time required for sample conditioning varies as a function of
many factors such as barrier composition, thickness, test
7. Reagents and Materials
temperature, etc.
7.1 Desiccant , for drying air stream.
10. Preparation of Test Apparatus and Calibration Pre-
7.2 High Purity Level Chromatograph Grade Distilled Wa-
Test Sample Considerations
ter (HPLC), for producing 100 % relative humidity.
7.3 Sealing Grease, a high-viscosity, silicone stopcock 10.1 Preparation of Apparatus (Fig. 1).
grease or other suitable silicone high-vacuum grease is re-
10.1.1 If preceding tests have exposed the apparatus to high
quired for lubrication of O-rings. moisture levels, outgas the system to desorb residual moisture.
7.4 Sample Holder, a cardboard or metal sample holder is Purge the system with dry air for a period of 3 to 4 hours.
supplied with the apparatus to facilitate loading of specimens. 10.2 Calibrating the System—Determine the transmission
rate of the system including the air gap and the guard film.
8. Sampling and Test Specimens
CalC is an acronym for the transmission rate of the apparatus
8.1 Select material for testing in accordance with standard
hardware, air gap, and guard film without any test specimens
methods of sampling applicable to the material under test.
present.
Sampling may be done in accordance with Practice D 1898 or
10.2.1 Fill the reservoir with HPLC water.
by 8.2 below.
10.2.2 Place a blank six position specimen holder in the
8.2 Selection samples considered representative of the ma-
system and tighten the clamp.
terial to be tested.
10.2.3 Adjust the gas flow to each cell for uniform RH
8.2.1 Primary Sampling Unit—Consider rolls, bolts, or
reading for all cells.
pieces of the flexible barrier material or nonwoven fabric to be
10.2.4 Set all cells to CalC.
the primary sampling unit, as applicable.
10.2.5 The computer will automatically determine the
8.2.2 Laboratory Sampling Unit—As a laboratory sampling
empty cell transmission rate (CalC) value for each cell.
unit, take from the primary sampling unit at least a one
11. Test Procedure
full-width piece that is 1 m (1yd.) in length along the (machine
direction, after first removinga1m(1 yd.) length.
11.1 Handle the test specimens carefully to avoid altering
8.2.2.1 For primary sampling units less than1m(1 yd.) in
the state of the material.
length, use a sufficient number of pieces to prepare the six
11.2 If permeability or permeance are to be calculated after
specimens to the size described in 8.2.3.
the test, measure specimen thickness at four equally spaced
8.2.3 Test Specimen Size—From each laboratory-sampling
points within the test area and at the center in accordance with
unit, cut at least six test specimens using the template supplied
guidelines described in Test Method D 5729.
with the apparatus or a similar die cutter. The truncated pie
11.3 Mount the specimens to the holder noting the material
shaped template will produce proper size specimens that cover
identity in each location. If testing a laminated material, mount
the sample cell.
the better barrier portion toward the carrier gas side of the test
cell and the poorer barrier toward the guard film.
11.4 Because of the type of material that is used for the
Linde Molecular Sieve, Type 4A or Type 5A, in the form of 1/8 in. pellets as
guard film, grease should not be used on either the lower cell
may be obtained from the Union Carbide Co., Linde Division, Danbury, CT
06817-0001. sealing surface or the upper cell O-ring.
D6701–01
11.5 Align the holder over the pins in the bottom portion of
r (T) = the density of water in saturated air at tempera-
sat
the cells of the apparatus, place the upper portion of the cells
ture, T, in °K,
on the base of the apparatus, and then tighten the clamp.
RH = the relative humidity at specified locations in the
11.6 Put the specimens into the test mode via the computer
cell,
keyboard. Enter the global test parameters and individual cell A = the cross section area of the cell, in cm , and,
p (T) = the saturation vapor pressure of water vapor, in
parameters. Place each cell into TEST.
sat
mmHg, at temperature, T.
11.6.1 Conditioning the Specimen—During the setting of
test parameters in the apparatus it is necessary to select to 12.1.2 The reported transmission rate is the result of
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