ASTM E96-00

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Designation: E 96 – 00
Standard Test Methods for
1
Water Vapor Transmission of Materials
This standard is issued under the fixed designation E 96; 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.
This standard has been approved for use by agencies of the Department of Defense.
A,B
TABLE 1 Metric Units and Conversion Factors
1. Scope
To Obtain (for the
1.1 These test methods cover the determination of water
Multiply by
same test condition)
vapor transmission (WVT) of materials through which the
WVT
passage of water vapor may be of importance, such as paper,
2 2
g/h·m 1.43 grains/h·ft
2 2
plastic films, other sheet materials, fiberboards, gypsum and
grains/h·ft 0.697 g/h·m
Permeance
plaster products, wood products, and plastics. The test methods
2 7
g/Pa·s·m 1.75 3 10 1 Perm (inch-pound)
1
are limited to specimens not over 1 ⁄4 in. (32 mm) in thickness
−8 2
1 Perm (inch-pound) 5.72 3 10 g/Pa·s·m
except as provided in Section 9. Two basic methods, the
Permeability
8
g/Pa·s·m 6.88 3 10 1 Perm inch
Desiccant Method and the Water Method, are provided for the
−9
1 Perm inch 1.45 3 10 g/Pa·s·m
measurement of permeance, and two variations include service
A
These units are used in the construction trade. Other units may be used in
conditions with one side wetted and service conditions with
other standards.
low humidity on one side and high humidity on the other. B
All conversions of mm Hg to Pa are made at a temperature of 0°C.
Agreement should not be expected between results obtained by
different methods. That method should be selected which more
nearly approaches the conditions of use.
3. Terminology
1.2 The values stated in inch-pound units are to be regarded
3.1 Definitions of terms used in this standard will be found
as the standard. Metric inch-pound conversion factors for
in Terminology C 168, from which the following is quoted:
WVT, permeance, and permeability are stated in Table 1. All
“water vapor permeability—the time rate of water vapor
conversions of mm Hg to Pa are made at a temperature of 0°C.
transmission through unit area of flat material of unit thickness
1.3 This standard does not purport to address all of the
induced by unit vapor pressure difference between two specific
safety problems, if any, associated with its use. It is the
surfaces, under specified temperature and humidity conditions.
responsibility of the user of this standard to establish appro-
3.1.1 Discussion—Permeability is a property of a material,
priate safety and health practices and determine the applica-
but the permeability of a body that performs like a material
bility of regulatory limitations prior to use.
may be used. Permeability is the arithmetic product of per-
meance and thickness.
2. Referenced Documents
“water vapor permeance—the time rate of water vapor
2.1 ASTM Standards:
transmission through unit area of flat material or construction
C 168 Terminology Relating to Thermal Insulating Materi-
induced by unit vapor pressure difference between two specific
2
als
surfaces, under specified temperature and humidity conditions.
D 449 Specification for Asphalt Used in Dampproofing and
3.1.2 Discussion—Permeance is a performance evaluation
3
Waterproofing
and not a property of a material.
D 2301 Specification for Vinyl Chloride Plastic Pressure-
3.2 water vapor transmission rate—the steady water vapor
4
Sensitive Electrical Insulating Tape
flow in unit time through unit area of a body, normal to specific
E 691 Practice for Conducting an Interlaboratory Study to
parallel surfaces, under specific conditions of temperature and
5
Determine the Precision of a Test Method
humidity at each surface.”
4. Summary of Test Methods
1
These test methods are under the jurisdiction of ASTM Committee C-16 on
4.1 In the Desiccant Method the test specimen is sealed to
Thermal Insulation and are the direct responsibility of Subcommittee C16.33 on
the open mouth of a test dish containing a desiccant, and the
Thermal Insulation Finishes and Vapor Transmission.
assembly placed in a controlled atmosphere. Periodic weigh-
Current edition approved April 10, 2000. Published July 2000. Originally
published as E 96 – 53 T. Last previous edition E 96 – 94.
ings determine the rate of water vapor movement through the
2
Annual Book of ASTM Standards, Vol 04.06.
specimen into the desiccant.
3
Annual Book of ASTM Standards, Vol 04.04.
4
4.2 In the Water Method, the dish contains distilled water,
Annual Book of ASTM Standards, Vol 10.01.
5
Annual Book of ASTM Standards, Vol 14.02. and the weighings determine the rate of vapor movement
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