EN ISO 12572:2016
(Main)Hygrothermal performance of building materials and products - Determination of water vapour transmission properties - Cup method (ISO 12572:2016)
Hygrothermal performance of building materials and products - Determination of water vapour transmission properties - Cup method (ISO 12572:2016)
ISO 12572:2016 specifies a method based on cup tests for determining the water vapour permeance of building products and the water vapour permeability of building materials under isothermal conditions. Different sets of test conditions are specified.
The general principles are applicable to all hygroscopic and non-hygroscopic building materials and products, including insulation materials and including those with facings and integral skins. Annexes give details of test methods suitable for different material types.
The results obtained by this method are suitable for design purposes, production control and for inclusion in product specifications.
Wärme- und feuchtetechnisches Verhalten von Baustoffen und Bauprodukten - Bestimmung der Wasserdampfdurchlässigkeit - Verfahren mit einem Prüfgefäß (ISO 12572:2016)
Diese Internationale Norm legt ein Verfahren zur Bestimmung des Wasserdampf-diffusions Durchlasskoeffizienten von Bauprodukten und des Wasserdampfdiffusionsleitkoeffizienten von Baustoffen unter isothermischen Bedingungen fest, das auf Prüfungen mit Prüfgefäßen basiert. Verschiedene Prüfbedingungen werden festgelegt.
Die allgemeinen Prinzipien gelten für alle hygroskopischen und nicht hygroskopischen Baustoffe und produkte einschließlich Wärmedämmstoffen und Baustoffen mit Beschichtungen oder Häuten. Einzelheiten zu Prüfverfahren, die für einzelne Stoffarten geeignet sind, sind in den Anhängen angegeben.
Die Ergebnisse, die nach diesem Verfahren erhalten werden, sind geeignet für die Bemessung, zur Produktionskontrolle und zur Aufnahme in Produktspezifikationen.
Performance hygrothermique des matériaux et produits pour le bâtiment - Détermination des propriétés de transmission de la vapeur d'eau - Méthode de la coupelle (ISO 12572:2016)
ISO 12572:2016 spécifie une méthode basée sur des essais en coupelle pour déterminer la perméance à la vapeur d'eau des produits pour le bâtiment ainsi que la perméabilité à la vapeur d'eau des matériaux pour le bâtiment dans des conditions isothermes. Différentes séries de conditions d'essai sont spécifiées.
Les principes généraux sont applicables à tous les matériaux et produits de bâtiment hygroscopiques et non hygroscopiques, y compris les matériaux isolants et ceux qui possèdent des parements et des revêtements intégrés. Les annexes fournissent des détails sur des méthodes d'essai convenant pour différents types de matériaux.
Les résultats obtenus par cette méthode peuvent être utilisés pour la conception, pour le contrôle de la production et pour insertion dans les spécifications de produits.
Higrotermalno obnašanje gradbenih materialov in proizvodov - Ugotavljanje lastnosti za prehod vodne pare - Metoda s čašami (ISO 12572:2016)
Ta dokument določa metodo, ki temelji na preskušanju v posodi za določanje prepustnosti vodne pare gradbenih proizvodov in prepustnosti vodne pare gradbenih materialov pri izotermnih pogojih.
Navedeni so različni sklopi preskusnih pogojev.
Splošna načela veljajo za vse higroskopske in nehigroskopske gradbene materiale in proizvode, vključno z izolacijskimi materiali in tistimi z dodanimi sloji ter vgrajenimi plašči. Dodatki podajajo podrobnosti preskusnih metod, ki so primerne za različne vrste materialov.
Rezultati, pridobljeni s to metodo, so primerni za potrebe projektiranja, kontrolo proizvodnje in vključitev v specifikacije izdelkov.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2016
1DGRPHãþD
SIST EN ISO 12572:2002
+LJURWHUPDOQRREQDãDQMHJUDGEHQLKPDWHULDORYLQSURL]YRGRY8JRWDYOMDQMH
ODVWQRVWL]DSUHKRGYRGQHSDUH0HWRGDVþDãDPL ,62
Hygrothermal performance of building materials and products - Determination of water
vapour transmission properties - Cup method (ISO 12572:2016)
Wärme- und feuchtetechnisches Verhalten von Baustoffen und Bauprodukten -
Bestimmung der Wasserdampfdurchlässigkeit - Verfahren mit einem Prüfgefäß (ISO
12572:2016)
Performance hygrothermique des matériaux et produits pour le bâtiment - Détermination
des propriétés de transmission de la vapeur d'eau - Méthode de la coupelle (ISO
12572:2016)
Ta slovenski standard je istoveten z: EN ISO 12572:2016
ICS:
91.100.01 Gradbeni materiali na Construction materials in
splošno general
91.120.30 =DãþLWDSUHGYODJR Waterproofing
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 12572
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2016
EUROPÄISCHE NORM
ICS 91.120.10 Supersedes EN ISO 12572:2001
English Version
Hygrothermal performance of building materials and
products - Determination of water vapour transmission
properties - Cup method (ISO 12572:2016)
Performance hygrothermique des matériaux et Wärme- und feuchtetechnisches Verhalten von
produits pour le bâtiment - Détermination des Baustoffen und Bauprodukten - Bestimmung der
propriétés de transmission de la vapeur d'eau - Wasserdampfdurchlässigkeit - Verfahren mit einem
Méthode de la coupelle (ISO 12572:2016) Prüfgefäß (ISO 12572:2016)
This European Standard was approved by CEN on 16 July 2016.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12572:2016 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 12572:2016) has been prepared by Technical Committee CEN/TC 89 “Thermal
performance of buildings and building components” the secretariat of which is held by SIS, in
collaboration with Technical Committee ISO/TC 163 “Thermal performance and energy use in the built
environment”.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2017, and conflicting national standards
shall be withdrawn at the latest by February 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 12572:2001.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 12572:2016 has been approved by CEN as EN ISO 12572:2016 without any modification.
INTERNATIONAL ISO
STANDARD 12572
Second edition
2016-08-01
Hygrothermal performance of
building materials and products —
Determination of water vapour
transmission properties — Cup method
Performance hygrothermique des matériaux et produits pour le
bâtiment — Détermination des propriétés de transmission de la
vapeur d’eau — Méthode de la coupelle
Reference number
ISO 12572:2016(E)
©
ISO 2016
ISO 12572:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
ISO 12572:2016(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols, units and subscripts . 1
3.1 Terms and definitions . 1
3.2 Symbols and units . 2
3.3 Subscripts . 3
4 Principle . 3
5 Apparatus . 3
6 Test specimens. 4
6.1 General principles for preparation of test specimens . 4
6.2 Dimensions of test specimens . 4
6.2.1 Shape and fit . 4
6.2.2 Exposed area . 4
6.2.3 Thickness of test specimens . 4
6.3 Number of test specimens . 5
6.4 Conditioning of test specimens . 5
6.5 Testing low resistance specimens . 5
7 Procedure. 5
7.1 Test conditions . 5
7.2 Preparation of specimen and test assembly . 7
7.3 Test procedure . 7
8 Calculation and expression of results . 8
8.1 Mass change rate . 8
8.2 Density of water vapour flow rate . 9
8.3 Water vapour permeance . 9
8.4 Water vapour resistance .10
8.5 Water vapour permeability .10
8.6 Water vapour resistance factor.10
8.7 Water vapour diffusion-equivalent air layer thickness .11
9 Accuracy of measurement .11
9.1 General .11
9.2 Specimen area .11
9.3 Specimen thickness .11
9.4 Sealants .12
9.5 Weighing precision .12
9.6 Control of environmental conditions .12
9.7 Variations in barometric pressure during test .12
10 Test report .12
Annex A (normative) Methods suitable for self-supporting materials .14
Annex B (normative) Methods suitable for loose fills .16
Annex C (normative) Methods suitable for membranes and foils .18
Annex D (normative) Methods suitable for mastics and sealants .19
Annex E (normative) Methods suitable for paint, varnishes, etc.21
Annex F (normative) Correction for the effect of a masked edge of a specimen .22
Annex G (normative) Correction for resistance of air layers .24
ISO 12572:2016(E)
Annex H (normative) Method for calculating the water vapour resistance of the air layer in
the cup .25
Annex I (informative) Weighing repeatability, weighing interval and specimen size needed
to achieve desired accuracy .26
Annex J (informative) Conversion table for water vapour transmission units.27
Bibliography .28
iv © ISO 2016 – All rights reserved
ISO 12572:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html
ISO 12572 was prepared by the European Committee Standardization (CEN) Technical Committee
CEN/TC 89, Thermal performance of buildings and building components, in collaboration with ISO
Technical Committee ISO/TC 163, Thermal performance and energy use in the built environment,
Subcommittee SC 1, Test and measurement methods, in accordance with the agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 12572:2001), which has been technically
revised with the following changes:
— addition of insulation materials in the Scope;
— addition of e) humidity chamber in Clause 5;
— addition of requirements regarding thickness of test specimen to measure the permeability of core
materials in 6.2.3;
— change of specimen area size in 6.3;
— addition of requirements for storage time and relative humidity for condition D in 6.4;
— new clause with requirements in 6.5;
— change of requirements for temperature and relative humidity for test conditions in 7.1;
— change of the calculation of mass change rate in 8.1;
— removal of 9.8.
INTERNATIONAL STANDARD ISO 12572:2016(E)
Hygrothermal performance of building materials and
products — Determination of water vapour transmission
properties — Cup method
1 Scope
This document specifies a method based on cup tests for determining the water vapour permeance of
building products and the water vapour permeability of building materials under isothermal conditions.
Different sets of test conditions are specified.
The general principles are applicable to all hygroscopic and non-hygroscopic building materials and
products, including insulation materials and including those with facings and integral skins. Annexes
give details of test methods suitable for different material types.
The results obtained by this method are suitable for design purposes, production control and for
inclusion in product specifications.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
There are no normative references in this document.
3 Terms, definitions, symbols, units and subscripts
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9346 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
density of water vapour flow rate
mass of water vapour transferred through the specimen per area and per time
3.1.2
homogeneous material
material with properties likely to affect the transmission of water vapour which do not vary on a
macroscopic scale
3.1.3
impermeable material
material with a measured water vapour diffusion-equivalent air layer thickness (3.1.8) greater than 1 500 m
3.1.4
water vapour permeance
density of water vapour flow rate (3.1.1) divided by the water vapour pressure difference between the
two specimen faces
ISO 12572:2016(E)
3.1.5
water vapour resistance
reciprocal of water vapour permeance (3.1.4)
3.1.6
water vapour permeability
product of the water vapour permeance (3.1.4) and the thickness of a homogeneous specimen
Note 1 to entry: Water vapour permeability can only be calculated for specimens of a homogeneous material
(3.1.2).
3.1.7
water vapour resistance factor
water vapour permeability (3.1.6) of air divided by that of the material concerned
Note 1 to entry: The water vapour resistance factor indicates how much greater the resistance of the material is
compared to an equally thick layer of stationary air at the same temperature.
3.1.8
water vapour diffusion-equivalent air layer thickness
thickness of a motionless air layer which has the same water vapour resistance (3.1.5) as the specimen
3.2 Symbols and units
Symbol Quantity Unit
A area of specimen m
G water vapour flow rate through specimen kg/s
R gas constant for water vapour = 462 N·m/(kg⋅K)
v
S hydraulic diameter of specimen m
T thermodynamic temperature K
W water vapour permeance with respect to partial vapour kg/(m ⋅s⋅Pa)
p
pressure
Z water vapour resistance with respect to partial vapour m ⋅s⋅Pa/kg
p
pressure
d mean thickness of specimen m
g density of water vapour flow rate kg/(m ⋅s)
l diameter of circle or side of square specimen m
m mass of specimen and cup assembly kg
p barometric pressure hPa
p standard barometric pressure = 1 013,25 hPa
S water vapour diffusion-equivalent air layer thickness m
d
t time s
Δp water vapour pressure difference across specimen Pa
v
δ water vapour permeability kg/(m⋅s⋅Pa)
p
δ water vapour permeability of air kg/(m⋅s⋅Pa)
a
μ water vapour resistance factor —
θ celsius temperature °C
φ relative humidity —
NOTE The above units comply with ISO 9346; a conversion table to other units commonly used in
permeability measurements is given in Annex J.
2 © ISO 2016 – All rights reserved
ISO 12572:2016(E)
3.3 Subscripts
Subscript Denoting
I interval
r repeatability
a air
c corrected for air layer
f film
j joint
m membrane
me masked edge
s specimen
t total
4 Principle
The test specimen is sealed to the open side of a test cup containing either a desiccant (dry cup) or
an aqueous saturated solution (wet cup). The assembly is then placed in a temperature and humidity
controlled test chamber. Because of the different partial vapour pressure between the test cup and the
chamber, a vapour flow occurs through permeable specimens. Periodic weighings of the assembly are
made to determine the rate of water vapour transmission in the steady-state.
5 Apparatus
a) Test cups resistant to corrosion from the desiccant or salt solutions they contain; typically cups are
made of glass or metal.
The design of cups suitable for testing various different types of materials is described in
Annexes A to E.
NOTE Circular cups can be easier to seal and transparent cups allow better control of salt solutions.
b) For certain cups and sealing methods (see Annex A), a template, with shape and size corresponding
to that of the test cup, is used when applying the sealant to give a sharply defined, reproducible test
area. The template shall have an area of at least 90 % of the specimen to limit nonlinear vapour flow.
c) Measuring instruments capable of determining specimen thickness with accuracy required in 7.2.
d) Analytical balance, capable of weighing the test assembly with the repeatability needed for the
required accuracy. Wherever possible, a balance of 0,001 g resolution shall be used. For heavy test
assemblies, a balance resolution of 0,01 g may be sufficient (see Annex I for information linking the
balance resolution to the duration of test).
NOTE The factors that affect the necessary accuracy of measurement are discussed in Annex I.
e) Constant temperature, constant humidity chamber, capable of being maintained within ±5 %
relative humidity around the set point relative humidity and ±1,0 K around the set point
temperature. In order to ensure uniform conditions throughout the chamber, the air shall be
stirred so as to obtain velocities between 0,02 m/s and 0,3 m/s. If highly permeable materials are
being tested, means should be provided to measure the air speed directly over the upper surface of
the specimen (see Annex G).
f) Suitable sensors and a logging system to continuously record the temperature, relative humidity
and, if necessary, the barometric pressure within the test chamber. The sensors shall be calibrated
at regular intervals.
ISO 12572:2016(E)
g) Sealant, which is impermeable to water vapour, does not undergo physical or chemical changes
during the test and does not cause physical or chemical changes to the specimen.
NOTE Examples of sealants suitable for specific materials, if necessary, are listed in the appropriate
Annex.
6 Test specimens
6.1 General principles for preparation of test specimens
The test specimens shall be representative of the product. If the product has natural skins or integral
facings, these may be included in the test specimen, but they shall be removed if it is intended to
measure the permeability of the core material. If the skins or facings are different on the two sides,
specimens shall be tested with vapour flow in the direction of the intended use. If the direction of flow
is not known, duplicate specimens shall be prepared and tests carried out for each direction of flow.
Unless the product to be tested is isotropic, the test specimens shall be cut so that the parallel faces are
normal to the direction of vapour flow of the product in use.
Specimen preparation shall not involve methods which damage the surface in ways which affect the
flow of water vapour.
6.2 Dimensions of test specimens
6.2.1 Shape and fit
Test specimens shall be cut to correspond with the dimensions of the chosen test assembly (see
Annexes A to E).
6.2.2 Exposed area
The diameter of a circular specimen or the side of a square specimen shall be at least twice the specimen
thickness. The exposed area (the arithmetic mean of the upper and lower free surface areas) shall be at
least 0,005 m . The upper and lower free surface areas shall not differ by more than 3 % of the mean in
the case of homogeneous materials and by no more than 10 % in the case of other materials.
6.2.3 Thickness of test specimens
Whenever possible, the thickness of the specimen shall be that of the product in use. In the case of
homogeneous materials, if the thickness exceeds 100 mm, this may be reduced by cutting. In the case
of non-homogeneous materials, such as concrete containing aggregates, the thickness should be at least
three times (and preferably five times) the largest particle size.
If a material contains macroscopic formed voids, the solid material should be tested and the resistance
of the whole material calculated from the proportions of solid to air space assuming one dimensional
vapour flow.
If it is necessary to test a product so thick that the available test cups do not have an area large enough
to comply with 6.2.2, the product may, only as a last resort, be sliced. In this case, all slices shall be
tested and the results reported.
If it is intended to measure the permeability of the core material, all skins and facings shall be removed
and the test specimens shall have a thickness of at least 20 mm.
NOTE There is a risk that this procedure leads to significant inaccuracies, especially when wet cup tests are
carried out on hygroscopic materials.
4 © ISO 2016 – All rights reserved
ISO 12572:2016(E)
6.3 Number of test specimens
If the specimen area is less than 0,05 m , a minimum of five specimens shall be tested, otherwise a
minimum of three specimens shall be tested.
6.4 Conditioning of test specimens
Before testing, the test specimens shall be stored at (23 ± 5) °C, (50 ± 5) % relative humidity for a
period long enough for their weight to stabilize so that three successive daily determinations of their
weight agree to within 5 %; a storage time of at least 6 h is necessary. If condition D in Table 1 is to be
used, the specimens should be conditioned at (38 ± 5) °C, (50 ± 5) % relative humidity.
NOTE This period will vary from a few hours in the case of some insulating materials to three to four weeks,
or more, for massive hygroscopic materials and products.
Wet field specimens may be dried before conditioning using the methods specified in ISO 12570.
A period of conditioning is not necessary in the case of plastic membranes.
6.5 Testing low resistance specimens
When testing low vapour resistance specimens with Sd < 0,1 m, use a wet cup, with distilled water
in the cup, giving a relative humidity of 100 % in the cup. The high flow rate through the specimen
prevents the occurrence of condensation on the underside of the specimen that is a risk with higher
resistance specimens. In this case, the size of the air gap between the water in the cup and the base of
the specimen shall be known to the nearest mm, and it is essential to maintain sufficient airspeed over
the top surface of the specimen (see Annex G).
NOTE Testing low vapour resistance specimens, with Sd < 0,1 m, can be difficult with either a wet cup or
a dry cup, because the water flow out of or into the cup can be large enough to affect the performance of the
saturated salt solution or desiccant before the test is complete. It is not therefore possible to carry out ”dry cup’”
tests with this type of material.
7 Procedure
7.1 Test conditions
Select the desired test environment from the conditions given in Table 1.
ISO 12572:2016(E)
Table 1 — Test conditions
Tolerances
a
Relative humidity
Condition °C -
Temperature
Set
%
% RH
°C Dry state Wet state
Set point Tolerance Set point Tolerance
A 23 – 0/50 23 ± 1 0 +5 50 ±5
B 23 – 0/85 23 ± 1 0 +5 85 ±5
C 23 – 50/93 23 ± 1 50 ±5 93 ±5
D 38 – 0/93 38 ± 1 0 +5 93 ±3
E 23 – 50/100 23 ± 1 50 ±5 100
NOTE 1 ”Dry cup” tests (condition A) give information about the performance of materials at low humidities
when moisture transfer is dominated by vapour diffusion. ”Wet cup” tests (condition C) give guidance about
the performance of materials under high humidity conditions. At higher humidities, the material pores
start to fill with water; this increases the transport of liquid water and reduces vapour transport. Tests in
this area therefore give some information about liquid water transport within materials. This is discussed
further in ISO 15148.
NOTE 2 Condition E is used for low resistance specimens (S ≤ 0,1 m).
d
a
Saturated salt solutions, which regulate the relative humidity in the cup at some value less than 100 %,
are used because, with many materials, there is a danger of condensation occurring on the underside of the
sample, which disrupts the vapour flow. In the case of very low resistance materials with Sd < 0,1 m, the
vapour flow rates are so high that a) condensation is unlikely and b) the saturated salt solution might not
remain in equilibrium for the duration of the rest. In this case, that distilled water should be used in the test
cup. Further information about the use of saturated salt solutions is given in 9.6.
Other sets of temperature and relative humidity may be agreed between the parties when needed for
special application conditions.
EXAMPLE 1 This is an example of desiccants which produce the specified air relative humidities at 23 °C.
Desiccants
Calcium chloride, CaCl - particle size < 3 mm 0 %
Magnesium perchlorate, Mg(ClO ) 0 %
4 2
Phosphorus pentoxide, P 0 0 %
2 5
Silicagel 0 %
EXAMPLE 2 This is an example of saturated aqueous solutions which produce the specified air relative
humidities at 23 °C.
Aqueous solutions
Sodium dichromate, Na Cr 0 · 2H 0 52 %
2 2 7 2
Magnesium nitrate, Mg(NO ) 53 %
3 2
Potassium chloride, KCl 85 %
Ammonium dihydrogen phosphate, NH H PO 93 %
4 2 4
Potassium nitrate, KNO 94 %
Further details of suitable solutions can be found in ISO 12571:2013, Annexes A and B.
Regular checks shall be made, especially during long tests, to ensure that saturated solutions remain as
a mixture of liquid with a large amount of undissolved substance.
6 © ISO 2016 – All rights reserved
ISO 12572:2016(E)
All chemical substances shall be handled with care and in accordance with relevant safety regulations.
7.2 Preparation of specimen and test assembly
Prepare test specimens to correspond to the test assembly used (see Annexes A to E). Measure the
thickness of specimens to the nearest 0,2 mm, or to an accuracy of ±0,5 %, whichever is the more
accurate. For rigid materials, measure the thickness of test specimens at four positions equally spaced
around the circumference. Calculate the mean thickness of each test specimen. Record the procedure
used to measure the effective thickness of compressible and loose-fill materials and of test specimens
with irregular surfaces.
Place the desiccant or aqueous solution, with a minimum depth of 15 mm, in the bottom of each cup.
Seal the test specimen into the cup, using the appropriate technique specified in the relevant Annex.
The air space between the desiccant or saturated solution and the specimen shall be (15 ± 5) mm. The
thickness of this layer shall be measured to the nearest mm to allow for its resistance to be calculated
(see Annex H).
NOTE 1 Once the distance between the base of the specimen and the desiccant or salt solution has been
measured once, weighing the cup with its contents can be used to achieve a repeatable gap.
The resistance of the layer above the specimen shall be reduced to zero by arranging an appropriate air
speed over the cup (see Annex G).
NOTE 2 The vapour flow rate depends on the vapour resistance of the specimen and the resistances of the
air layers above and below the specimen. In the case of high resistance specimens, these air resistances are
negligible, but for low resistance materials with S < 0,1 m, they are significant.
d
Prepare a test assembly using a cup and sealant system suitable for the type of material under test (see
Annexes A to E).
NOTE 3 The accuracy and repeatability of the results are strongly dependent on the quality of the sealing,
especially for high resistance specimens. Therefore, close attention needs to be given to the method of applying
sealing. Initial tests can be carried out with an impermeable metal specimen to test that the resultant vapour
flow rate is zero. Further information on sealing is given in 9.4.
7.3 Test procedure
Place the test assemblies in the test chamber. Then, weigh in turn each test assembly at time intervals
selected according to the specimen characteristics and to the repeatability of the weighing procedure.
NOTE Annex I gives guidance on the ways of reaching the required accuracy.
Weighings shall be carried out in an environment with a temperature within ±2 °C of the test condition,
wherever possible within the test chamber. Figure 1 shows an arrangement for small chambers.
The temperature and relative humidity within the test chamber shall be recorded continuously with
suitable sensors. The calibration of the sensors shall be checked regularly.
The barometric pressure at the testing laboratory shall be measured daily during the test or obtained
from a closely adjacent meteorological station.
ISO 12572:2016(E)
Key
1 balance
2 controlled environment test chamber with ‘glove box’ access door
3 suspended weighing platform
4 test assembly during weighing
Figure 1 — Example of an arrangement of balance and test assemblies for weighing procedures
in a chamber
Continue weighings until five successive determinations of change in mass per weighing interval for
each test specimen are constant within ±5 % of the mean value for this specimen (or within ±10 % for
low permeance materials with μ > 750 000) and until the change in weight of the cup assembly exceeds
100 times the repeatability of the weighing procedure.
Plot a curve of change in mass against time to facilitate recognition of the condition of constant mass
change rate.
The test shall be terminated prematurely when
a) in a dry cup test, the assembly has gained more than 1,5 g per 25 ml of desiccant in the cup, or
b) in a wet cup test, the weight loss is half the initial mass of the solution in the cup.
8 Calculation and expression of results
8.1 Mass change rate
For each set of successive weighings of the specimens, calculate the mass change rate,Dm , using
Formula (1).
mm-
Dm = (1)
tt-
8 © ISO 2016 – All rights reserved
ISO 12572:2016(E)
where
is the change of mass per time for a single determination, in kg/s;
Dm
m is the mass of the test assembly at time t , in kg;
1 1
m is the mass of the test assembly at time t , in kg;
2 2
t and t are the successive times of weighings, in s.
1 2
Calculate G, the mean of five successive determinations of Dm , for each test specimen.
The final value of G is obtained when each of the last five successive determinations of Dm is within
±5 % of G.
8.2 Density of water vapour flow rate
The density of water vapour flow rate, g, is given by Formula (2).
G
g= (2)
A
where
A is the exposed area (arithmetic mean of the free upper and free lower surface areas) of the
test specimen, in m .
If a cup and sealant system which includes a “masked edge” (see Annex A) has been used, values shall be
corrected before being used to calculate further parameters (see Annex F).
8.3 Water vapour permeance
The water vapour permeance, W, is given by Formula (3).
G
W = (3)
A⋅Δp
The value of Δp shall be calculated from the means of the measured temperatures and relative
v
humidities over the course of the test[see Formula (4)].
NOTE Reference [5] contains methods on how to calculate the vapour pressure on either side of the specimen
from the temperature and relative humidity for temperatures greater than 0 °C.
17,269⋅θ
237,3+θ
p =⋅φ 610,5⋅e (4)
If highly permeable materials or thin membranes with s < 0,2 m, are being tested, the resistance of
d
the air gap between the base of the sample and the desiccant or saturated solution shall be taken into
account in the calculation of W (see Annex G).
Table 2 summarizes the values of Δp for the five test conditions specified in Table 1.
ISO 12572:2016(E)
Table 2 — Δp values for each test condition
Set Condition Δp Pa
°C - % RH
A 23 - 0/50 1 404
B 23 - 0/85 2 387
C 23 - 50/93 1 207
D 38 - 0/93 6 157
E 23 - 50/100 1 404
8.4 Water vapour resistance
The water vapour resistance, Z, is the reciprocal of the water vapour permeance [see Formula (5)].
Z= (5)
W
8.5 Water vapour permeability
The water vapour permeability, δ, is given by Formula (6).
δ =⋅Wd (6)
8.6 Water vapour resistance factor
The water vapour resistance factor, μ, is defined by Formula (7).
δair
μ = (7)
δ
Formula (7), known as the Schirmer formula, is used to calculate δ , using the mean barometric
a
pressure, p, over the test [see Formula (8)].
18, 1
0, 086 p
Τ
δ = (8)
a
Rp⋅⋅Τ 273
D
−6
With R , the gas constant of water vapour 462,10 Nm/(mg.K).
D
Values of δ at 23 °C are shown in Figure 2.
a
The water vapour permeability of air and the material may be assumed to vary equally with the
barometric pressure. The factor μ can therefore be considered independent of barometric pressure.
When calculating the value of μ using the expression in Formula (9).
Δp.δair
μ = (9)
gd.
the value of δ shall correspond to the actual barometric pressure.
a
10 © ISO 2016 – All rights reserved
ISO 12572:2016(E)
Figure 2 — Water vapour permeability of air as a function of barometric pressure at 23°C
8.7 Water vapour diffusion-equivalent air layer thickness
The water vapour diffusion-equivalent air layer thickness, s , is given by either Formula (10) or
d
Formula (11).
s = μ⋅d (10)
d
s = δ ⋅Z (11)
d a
9 Accuracy of measurement
9.1 General
Clause 9 and Annex I discuss the factors that affect the accuracy of the result and give guidance on how
to improve it, if necessary.
NOTE A number of “round-robin” intercomparisons of measurements by different laboratories have been
carried out (see References [8],[11] and[14] for discussion of the results).
A number of factors affect the accuracy of the measured values.
9.2 Specimen area
The diameter of a circular test cup or the side of a square test cup shall be measured to an accuracy
of ±0,5 mm, giving a possible error in the area of a specimen of the minimum size specified in 6.2.2
(i.e. 0,05 m ) of ±0,5 %. This error will be less with larger specimens. For certain cup types, it will be
necessary to correct for the effect of a masked edge as specified in Annex F.
9.3 Specimen thickness
If the permeance or resistance of a complete product is being measured, the accuracy is not affected
by the thickness. However, if the permeability of a material is needed, the accuracy with which the
specimen thickness can be measured will directly effect the accuracy of the result. The thickness of a
rigid specimen can be measured to better than 0,5 % with a micrometer.
NOTE The accuracy will be lower in the case of loose fill and similar materials.
ISO 12572:2016(E)
9.4 Sealants
If an appropriate sealant is installed as specified in the Annexes, errors caused by leakage can be much
less than those from other sources. A faulty seal will result in a much higher flow rate through one of
the test assemblies. That result shall be rejected before averages are taken over the samples.
Close attention should be given to the method of applying sealing and laboratory staff should be trained
accordingly. It is recommended that initial tests are carried out with an impermeable metal specimen
to test that the resultant vapour flow rate is zero.
9.5 Weighing precision
The influence of weighing uncertainty on the accuracy of the results depends on the size of the specimen
and the time interval between successive weighings.
NOTE I
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...