Rubber materials for seals and diaphragms for gas appliances and gas equipment

This standard specifies requirements and associated test methods for rubber materials used in gas installations, gas equipment and gas appliances in contact with 1st, 2nd and 3rd family combustible gases as classified in EN 437 e.g. natural gas, LPG, bio methane bio LPG. It also establishes a classification based on temperature range and hardness. This standard is applicable to materials from which are manufactured homogeneous seals and homogeneous or reinforced diaphragms.
Since the dimensions and shape of the components differ from those of standard test pieces taken from sheet material as used for type testing of the rubber materials according to this standard, tolerances have been made in the requirements specified by Annex A for the components with respect to those specified for standard test pieces.
The range of operating temperatures covered by this standard is - 40 °C to + 150 °C.
This standard is not applicable for silicone rubber used either above 200 hPa (200 mbar) nominal pressure or at temperatures below 0 °C with 3rd family gases, as there is the possibility of condensation.

Elastomer-Werkstoffe für Dichtungen und Membranen in Gasgeräten und Gasanlagen

Diese Norm legt Anforderungen und zugehörige Prüfverfahren für Elastomer-Werkstoffe fest, die in Gasgeräte und Gasanlagen in Kontakt mit Brenngasen der 1., 2. und 3. Gasfamilie, wie in EN 437 klassifiziert z. B. Erdgas, Flüssiggas, Bio-Erdgas und Bio-Flüssiggas, eingesetzt werden. Sie stellt außerdem eine Klassifizierung nach Temperaturbereich und Härte auf. Diese Norm gilt für Werkstoffe, aus denen homogene Dichtungen und homogene oder verstärkte Membranen hergestellt werden.
Da die Abmessungen und die Form der Fertigteile von denen genormter Probekörper, hergestellt aus Plattenmaterial, wie sie zur Typprüfung von Elastomer-Werkstoffen nach dieser Norm verwendet werden, abweichen, wurden größere Toleranzen in den für Fertigteile in Anhang A festgelegten Anforderungen gegenüber den für Normprobekörper festgelegten Anforderungen eingeräumt.
Der Bereich der Betriebstemperaturen, der von dieser Norm abgedeckt wird, reicht von − 40 °C bis + 150 °C.
Diese Norm gilt weder für den Einsatz von Silikongummi bei Nenndruck über 200 hPa (200 mbar) noch bei Temperaturen unter 0 °C in Kontakt mit Gasen der 3. Gasfamilie, da unter diesen Umständen Kondensation möglich ist.

Matériaux à base de caoutchouc pour joints d'étanchéité et membranes destinés aux appareils à gaz et appareillages pour le gaz

La présente norme définit les exigences et les méthodes d'essai associées relatives aux matériaux en caoutchouc utilisés dans les installations, appareils d'utilisation et équipement de gaz en contact avec les combustibles gazeux de première, deuxième ou troisième famille selon la classification de l'EN 437, par exemple, gaz naturel, GPL, biométhane, bio GPL. Elle établit également une classification basée sur une gamme de températures et de duretés. La présente norme est applicable aux matériaux à partir desquels sont fabriqués les joints d’étanchéité homogènes et les membranes homogènes ou renforcées.
Étant donné que les dimensions et la forme des pièces diffèrent de celles des éprouvettes normalisées prélevées dans des plaques du matériau et utilisées pour les essais de type des matériaux en caoutchouc au sens de la présente norme, des tolérances ont été apportées aux exigences spécifiées pour les pièces, à l'Annexe A, par rapport à celles spécifiées pour les éprouvettes normalisées.
La gamme de températures de service couverte par la présente norme est de - 40 °C à + 150 °C.
La présente norme n'est pas applicable au caoutchouc silicone utilisé au-dessus d'une pression nominale de 200 hPa (200 mbar) ou à des températures inférieures à 0 °C avec la troisième famille de gaz, car il y a possibilité de condensation.

Gumeni materiali za tesnila in membrane v plinskih aparatih in plinskih napravah

Ta standard določa zahteve in z njimi povezane preskusne metode za gumene materiale, ki se uporabljajo v plinskih napravah, plinski opremi in plinskih aparatih v stiku z vnetljivimi plini razredov 1, 2 in 3, razvrščenimi v skladu s standardom EN 437, npr. zemeljski plin, utekočinjeni naftni plin, bioplin, bio-metan. Vzpostavlja tudi razvrstitev glede na temperaturno območje delovanja in trdoto. Ta standard se uporablja za materiale, iz katerih so izdelana homogena tesnila in homogene ali ojačane membrane.
Ker se mere in oblika komponent razlikujejo od standardnih preskušancev iz plastnega materiala, ki se uporabljajo za preskušanje tipa gumenih materialov v skladu s tem standardom, so bila v delih, določenih v dodatku A, določena dovoljena odstopanja za komponente glede na tiste, ki veljajo za standardne preskušance.
Temperaturno območje delovanja, ki ga zajema ta standard, je od –40 do 150 °C.
Ta standard se ne uporablja za silikonsko gumo, ki se uporablja bodisi pri nominalnem tlaku nad 200 hPa (200 mbar) bodisi pri temperaturah pod 0 °C s plini razreda 3, saj obstaja možnost kondenzacije.

General Information

Status
Published
Public Enquiry End Date
31-Jul-2017
Publication Date
08-Aug-2019
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
19-Jun-2019
Due Date
24-Aug-2019
Completion Date
09-Aug-2019

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SLOVENSKI STANDARD
SIST EN 549:2019
01-september-2019
Nadomešča:
SIST EN 549:1996
Gumeni materiali za tesnila in membrane v plinskih aparatih in plinskih napravah
Rubber materials for seals and diaphragms for gas appliances and gas equipment
Elastomer-Werkstoffe für Dichtungen und Membranen in Gasgeräten und Gasanlagen

Matériaux à base de caoutchouc pour joints d'étanchéité et membranes destinés aux

appareils à gaz et appareillages pour le gaz
Ta slovenski standard je istoveten z: EN 549:2019
ICS:
83.140.50 Tesnila Seals
91.140.40 Sistemi za oskrbo s plinom Gas supply systems
SIST EN 549:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 549:2019
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SIST EN 549:2019
EN 549
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2019
EUROPÄISCHE NORM
ICS 83.140.50 Supersedes EN 549:1994
English Version
Rubber materials for seals and diaphragms for gas
appliances and gas equipment

Matériaux à base de caoutchouc pour joints Elastomer-Werkstoffe für Dichtungen und Membranen

d'étanchéité et membranes destinés aux appareils à in Gasgeräten und Gasanlagen
gaz et matériels pour le gaz
This European Standard was approved by CEN on 22 April 2019.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, 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: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 549:2019 E

worldwide for CEN national Members.
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SIST EN 549:2019
EN 549:2019 (E)
Contents Page

European foreword ....................................................................................................................................................... 4

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 6

2 Normative references .................................................................................................................................... 6

3 Terms and definitions ................................................................................................................................... 7

4 Product's information ................................................................................................................................... 7

5 Classification ..................................................................................................................................................... 8

6 Requirements ................................................................................................................................................... 9

6.1 General ................................................................................................................................................................ 9

6.2 Requirements for rubber material used to manufacture seals ...................................................... 9

6.3 Requirements for rubber material used to manufacture diaphragms ..................................... 10

7 Test methods ................................................................................................................................................. 12

7.1 General ............................................................................................................................................................. 12

7.2 Hardness .......................................................................................................................................................... 12

7.3 Tensile strength and elongation at break ........................................................................................... 12

7.4 Compression set ........................................................................................................................................... 12

7.5 Resistance to ageing .................................................................................................................................... 12

7.6 Resistance to gas .......................................................................................................................................... 12

7.7 Resistance to condensate/liquid phase of combustible gases ..................................................... 13

7.8 Resistance to lubricants ............................................................................................................................. 13

7.9 Resistance to ozone ..................................................................................................................................... 13

8 Evaluation of life-time for material used to manufacture seals .................................................. 15

9 Infrared spectra of the material ............................................................................................................. 16

Annex A (normative) Requirements and test of components ................................................................... 17

A.1 Scope ................................................................................................................................................................. 17

A.2 Requirements ................................................................................................................................................ 17

A.2.1 General ............................................................................................................................................................. 17

A.2.2 Physical and chemical properties of seals .......................................................................................... 17

A.2.3 Physical and chemical properties of diaphragms ............................................................................ 17

A.3 Tests methods for components ............................................................................................................... 17

A.3.1 General ............................................................................................................................................................. 17

A.3.2 Hardness .......................................................................................................................................................... 17

A.3.3 Resistance to ageing .................................................................................................................................... 18

A.3.4 Resistance to gas .......................................................................................................................................... 18

A.3.5 Resistance to condensate/liquid phase of combustible gas ......................................................... 18

A.3.6 Resistance to lubricants ............................................................................................................................. 18

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SIST EN 549:2019
EN 549:2019 (E)

A.3.7 Resistance to ozone ...................................................................................................................................... 19

Annex B (normative) Infrared spectra of the material ................................................................................ 23

B.1 Scope ................................................................................................................................................................. 23

B.2 Requirements ................................................................................................................................................. 23

B.2.1 General ............................................................................................................................................................. 23

B.2.2 Solvent extract ............................................................................................................................................... 23

B.2.3 Infrared spectra ............................................................................................................................................ 23

B.2.4 Density .............................................................................................................................................................. 23

B.3 Methods of test .............................................................................................................................................. 23

B.3.1 General ............................................................................................................................................................. 23

B.3.2 Solvent extraction ......................................................................................................................................... 23

B.3.3 Infrared spectra ............................................................................................................................................ 24

B.3.4 Density .............................................................................................................................................................. 24

Annex C (normative) Evaluation of lifetime for material used to manufacture seals by using

the compression set method .................................................................................................................... 25

C.1 General ............................................................................................................................................................. 25

C.2 Requirements ................................................................................................................................................. 26

C.3 Test Procedure .............................................................................................................................................. 26

C.4 Evaluation of Test Results ......................................................................................................................... 27

C.5 Documentation .............................................................................................................................................. 28

Annex D (informative) Verification of identity of material ........................................................................ 29

D.1 Scope ................................................................................................................................................................. 29

D.2 Verification requirements ......................................................................................................................... 29

D.2.1 General ............................................................................................................................................................. 29

D.2.2 Solvent extract ............................................................................................................................................... 29

D.2.3 Infrared spectra ............................................................................................................................................ 29

D.2.4 Density .............................................................................................................................................................. 29

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Regulation 2016/426 aimed to be covered ....................................................... 30

Bibliography ................................................................................................................................................................. 31

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SIST EN 549:2019
EN 549:2019 (E)
European foreword

This document (EN 549:2019) has been prepared by Technical Committee CEN/TC 208 “Elastomeric

seals for joints in pipework and pipelines”, the secretariat of which is held by BSI.

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 January 2020, and conflicting national standards shall

be withdrawn at the latest by January 2020.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 549:1994.

This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association, and supports essential requirements of EU Regulation 2016/426

relating to appliances burning gaseous fuels.

For relationship with EU Regulation 2016/426, see informative Annex ZA, which is an integral part of this

document.
The following main technical changes have been made compared to EN 549:1994:

a) Clause 8, “Evaluation of life-time for material used to manufacture seals” added;

b) Clause 9, “Infrared spectra of the material” added;
c) resistance to condensate/liquid phase of combustible gases added;
d) low temperature classes added;
e) ozone resistance for diaphragms is now mandatory;
f) informative Annex D added.

NOTE Verification of identity of material is described in the informative Annex D.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,

Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,

Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North

Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United

Kingdom.
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SIST EN 549:2019
EN 549:2019 (E)
Introduction

This document specifies the requirements for rubber materials to be used for the manufacture of seals

and diaphragms. It specifies for that purpose, tests to be carried out on standardized test pieces taken

from sheets of material, since the small size of most components in general does not allow the preparation

of necessary test samples for carrying out the complete range of tests.

It may be necessary to carry out supplementary tests on the component mounted in the gas appliance or

in equipment, to confirm the functional suitability of the component. Such tests should be performed

under the most severe service conditions envisaged in the appropriate standards for the gas appliances

and/or equipment.
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SIST EN 549:2019
EN 549:2019 (E)
1 Scope

This document specifies requirements and associated test methods for rubber materials used in gas

installations, gas equipment and gas appliances in contact with 1st, 2nd and 3rd family combustible gases

as classified in EN 437:2018, additionally LPG, bio methane and bio LPG, in the same quality, are covered.

It also establishes a classification based on temperature range and hardness. This document is applicable

to materials from which homogeneous seals and homogeneous or reinforced diaphragms are

manufactured.

Since the dimensions and shape of the components differ from those of standard test pieces taken from

sheet material as used for type testing of the rubber materials according to this document, tolerances

have been made in the requirements specified by Annex A for the components with respect to those

specified for standard test pieces.

The range of operating temperatures covered by this document is –40 °C to +150 °C.

For applications with potential condensation, this document is not applicable for silicon rubber, e.g. above

200 hPa (200 mbar) nominal pressure or at temperatures below 0 °C with 3rd family gases.

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.

EN ISO 1183-1:2019, Plastics - Methods for determining the density of non-cellular plastics - Part 1:

Immersion method, liquid pycnometer method and titration method (ISO 1183-1:2019)

ISO 37:2017, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties

ISO 48-2:2018, Rubber, vulcanized or thermoplastic — Determination of hardness – Part 2: Hardness

between 10 IRHD and 100 IRHD

ISO 188:2011, Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests

ISO 815-1:2014, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 1: At

ambient or elevated temperatures

ISO 815-2:2014, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 2: At low

temperatures
ISO 1407:2011, Rubber — Determination of solvent extract

ISO 1431-1:2012, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and

dynamic strain testing

ISO 1817:2015, Rubber, vulcanized or thermoplastic — Determination of the effect of liquids

ISO 4650:2012, Rubber — Identification — Infrared spectrometric methods

ISO 23529:2016, Rubber — General procedures for preparing and conditioning test pieces for physical test

methods
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SIST EN 549:2019
EN 549:2019 (E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
rubber material
vulcanised mixture of rubber and ingredients used to manufacture rubber material
3.2
component
finished product manufactured from rubber material
Note 1 to entry For example. O-Rings, diaphragms, …
3.3
seal

component used as an interface between parts of a gas appliance or parts of gas equipment to ensure gas

tightness
3.4
diaphragm

component located in a fixture and serving as a flexible gas tight partition between two chambers

3.5
reinforcement

material arranged in or on the elastomeric material, thus reinforcing certain properties of such

Note 1 to entry: For example, the bursting strength of diaphragms.
3.6
rubber compound
mixture of raw rubber and ingredients used to manufacture rubber material
4 Product's information
The following information shall be documented:
— a unique rubber material reference;
— the nominal hardness;
— the maximum working temperature;
— the minimum working temperature;
— whether the material is resistant to ozone;

— whether the material is resistant to condensate/liquid phase of combustible gas;

— for reinforced material, a full specification of the reinforcement, including at least:

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SIST EN 549:2019
EN 549:2019 (E)
— type of material (for example polyester, nylon, cotton or silk);
— grammage (g/m );
— yarn type;
— basic construction;
— yarn count in warp and weft;
— yarn twist.

Diaphragms shall be ozone resistant. Due to the potential risk of damage of any protective surface coating,

such as waxes, by dynamic flexing such methods of protection against ozone attack shall not be used

without additional protective additives.
5 Classification

Materials shall be classified according to temperature range and hardness as given in Table 1 and Table 2

respectively.
Table 1 — Temperature classes
Range of operating temperature (°C)
Class
from to
A1 0 60
B1 0 80
C1 0 100
D1 0 125
E1 0 150
A2 −20 60
B2 −20 80
C2 −20 100
D2 −20 125
E2 −20 150
A3 −30 60
B3 −30 80
C3 −30 100
D3 −30 125
E3 −30 150
A4 −40 60
B4 −40 80
C4 −40 100
D4 −40 125
E4 −40 150
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SIST EN 549:2019
EN 549:2019 (E)
Table 2 — Hardness classes
Class H1 H2 H3
Nominal
hardness range
< 45 45 to 60 > 60 to 90
(IRHD-M)

EXAMPLE The classification of a rubber material applicable over the temperature range of –20 °C to +80 °C

with a declared nominal hardness of 70 IRHD-M would be B2/H3.
6 Requirements
6.1 General

Test pieces shall be free from internal and external defects such as porosity, inclusion, blisters and surface

imperfections visible to the naked eye.
6.2 Requirements for rubber material used to manufacture seals

When tested in accordance with the methods detailed in Clause 7 standard test pieces shall be used. The

material shall comply with the requirements given in Table 3.
Table 3 — Requirements for rubber material used to manufacture seals
Hardness class
Property Unit
H1 H2 H3
Hardness
Tolerance on stated nominal hardness IRHD-M ±5 ±5 ±5
Tensile strength MPa ≥ 5 ≥ 7 ≥ 7
Elongation at break % ≥ 125 ≥ 125 ≥ 125
Compression set
a % ≤ 40 ≤ 40 ≤ 40
— at high temperature
— at low temperature 0 °C % ≤ 40 ≤ 40 ≤ 40
— at low temperature −20 °C % ≤ 50 ≤ 50 ≤ 50
— at low temperature −30 °C % ≤ 70 ≤ 70 ≤ 70
— at low temperature −40 °C % ≤ 75 ≤ 75 ≤ 75
Resistance to ageing
— change in hardness, max. IRHD-M ±10 ±10 ±10
— change in tensile strength, max. % − 40 − 40 − 40
— change in elongation at break, max. % − 40 − 40 − 40
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SIST EN 549:2019
EN 549:2019 (E)
Hardness class
Property Unit
H1 H2 H3
Resistance to gas
— change in mass after immersion, max. %
+10 +10 +10
−5 −5 −5
— change in mass after drying, max. %
+5 +5 +5
−8 −8 −8
Resistance to condensate/liquid phase of
combustible gases
— change in mass after immersion, max. % + 20 + 20 + 20
— change in mass after drying, max. % − 15 − 12 − 10
Resistance to lubricant
— change in hardness, max. IRHD-M ±10 ±10 ±10
— change in mass, max. %
+15 +15 +15
−10 −10 −10
e no cracks
Resistance to ozone

The test piece shall not be damaged by adhering to the surface of the test apparatus.

For silicone material there is no requirement for change in mass after immersion as swelling by some such

materials may be substantial, the requirement for change in mass after drying, is ± 5 %.

This requirement is only applicable if the material has been declared as resistant to condensate/liquid phase

of combustible gases
+10

For silicone material the requirement for change in hardness and mass are ± 15 IRHD and % respectively.

This requirement is only applicable if the material has been declared to be ozone resistant.

6.3 Requirements for rubber material used to manufacture diaphragms

When tested in accordance with the methods detailed in Clause 7standard test pieces shall be used.

The material used to manufacture diaphragms shall comply with the requirements given in Table 4.

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SIST EN 549:2019
EN 549:2019 (E)
Table 4 — Requirements for rubber material used to manufacture diaphragms
Hardness class
Property Unit
H1 H2 H3
Hardness
Tolerance on stated nominal hardness IRHD-M ±5 ±5 ±5
Tensile strength MPa ≥ 5 ≥ 7 ≥ 10
Elongation at break % ≥ 500 ≥ 300 ≥ 200
Compression set
— at high temperature % ≤ 35 ≤ 25 ≤ 25
— at low temperature 0 °C % ≤ 40 ≤ 40 ≤ 40
— at low temperature – 20 °C % ≤ 50 ≤ 50 ≤ 50
— at low temperature – 30 °C % ≤ 70 ≤ 70 ≤ 70
— at low temperature – 40 °C % ≤ 75 ≤ 75 ≤ 75
Resistance to ageing
— change in hardness, max. IRHD-M ±8 ±8 ±8
— change in tensile strength, max. % − 15 − 15 − 15
— change in elongation at break, max. % − 25 − 25 − 25
Resistance to gas
— change in mass after immersion, max. % ±10
+10 +10
−5 −5
— change in mass after drying, max. %
+5 +5 +5
−15 −10 −8
Resistance to condensate/liquid phase of combustible
gases
— change in mass after immersion, max. % + 20 + 20 + 20
— change in mass after drying, max. % − 15 − 12 − 10
Resistance to lubricant
— change in hardness, max. IRHD-M ±10 ±10 ±10
— change in mass, max. %
+15 +15 +15
−10 −10 −10
Resistance to ozone no cracks

The test piece shall not be damaged by adhering to the surface of the test apparatus.

This requirement excludes the use of silicone material. In some applications it may be possible to leave the

requirement for change in mass after immersion when care is taken that:
— there is no risk of formation of gas condensate in the application;
— the permeation rate is no problem in the application;
— the low tear resistance is compensated by reinforcement or construction.

This requirement is only applicable if the material has been declared as resistant to condensate/liquid phase

of combustible gases
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SIST EN 549:2019
EN 549:2019 (E)
7 Test methods
7.1 General
In addition to the conditions below, Table 5 shall be considered.

Test pieces shall be cut from a sheet of material of (2 ± 0,2) mm or (6,3 ± 0,3) mm thickness as specified

in the method of test. Measurements of thickness shall be carried out as specified in ISO 23529:2016.

The material shall be from the same compound formulation used to make the component, vulcanized

under conditions which are comparable to those used in production.
7.2 Hardness

Five measurements shall be taken using ISO 48-2:2018, method M on each of three test samples of sheet

material at a test temperature of (23 ± 2) °C.
7.3 Tensile strength and elongation at break

Measurements are carried out on six dumb-bell test pieces, type 2, in accordance with the test method

given in ISO 37:2017 at a test temperature of (23 ± 2) °C.
7.4 Compression set

7.4.1 Tests at ambient or elevated temperature shall be performed on three cylindrical disc test pieces

of (13 ± 0,5) mm diameter and (6,3 ± 0,3) mm thickness in accordance with the method given in

ISO 815-1:2014. For test temperatures and durations of tests, see Table 5.

7.4.2 Tests at low temperatures shall be performed on three cylindrical disc test pieces of

(13 ± 0,5) mm diameter and (6,3 ± 0,3) mm thickness in accordance with ISO 815-2:2014. For test

temperatures and durations of tests, see Table 5.
7.5 Resistance to ageing

Dumb-bell test pieces type 2 (six for both tensile strength and elongation at break and three for hardness

testing) are tested in accordance with ISO 188:2011 using a normal air oven under the following special

conditions:
— duration of ageing: 168 h;
— test temperature: see Table 5.

NOTE It is permissible for the hardness test to be carried out on the tensile strength test pieces before tensile

strength testing.
7.6 Resistance to gas

Three test pieces of dimension 50 mm × 20 mm × 2 mm shall be tested in accordance with

ISO 1817:2015, 7.2 using apparatus in accordance with ISO 1817:2015, 3.1 and the following special

conditions:
— immerse for 72 h at (23 ± 2) °C in n-pentane;
NOTE 98 % minimum n-pentane by mass, measured by gas chromatography.
— after removal from the liquid, wipe dry rapidly and weigh immediately;
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SIST EN 549:2019
EN 549:2019 (E)
— determine the change in mass with reference to the initial mass of the sample;
— dry the test specimens for a period of h in a normal air oven at (40 ± 2) °C;
168

— determine the new change in mass with reference to the initial mass of the sample.

Calculate the arithmetic mean values of the three results both after immersion and after drying.

7.7 Resistance to condensate/liquid phase of combustible gases

Three test pieces of dimension 50 mm × 20 mm × 2 mm shall be tested in accordance with

ISO 1817:2015, 7.2 using apparatus in accordance with ISO 1817:2015, 3.1 and the following special

conditions:
— immerse for 72 h at (23 ± 2) °C in liquid B;
— after removal from the liquid, wipe dry rapidly and weigh immediately;
— determin
...

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