ISO 9553:1997

Solar energy - Methods of testing preformed rubber seals and sealing compounds used in collectors

Énergie solaire — Méthodes d'essai des joints préformés en caoutchouc et des composés pour l'étanchéité utilisés dans les capteurs

General Information

• Status: Published
• Publication Date: 15-Oct-1997
• ICS: 27.160 - Solar energy engineering
• ICS: 83.140.50 - Seals
• Technical Committee: ISO/TC 180 - Solar energy
• Drafting Committee: ISO/TC 180 - Solar energy
• Current Stage: 9092 - International Standard to be revised
• Start Date: 13-Oct-2025
• Completion Date: 13-Dec-2025

Overview

ISO 9553:1997 - "Solar energy - Methods of testing preformed rubber seals and sealing compounds used in collectors" specifies classification and laboratory test methods to evaluate rubbers and sealants used to seal solar collectors. It helps manufacturers, designers and test laboratories select and verify seal materials for service conditions (thermal cycling, UV/weathering, ozone, low temperature and adhesion). The standard covers material requirements, dimensional tolerances and detailed test procedures (including an Annex A adhesion test).

Key topics and technical requirements

• Classification of seals by service temperature (Types B…H) and by climatic class for low-temperature performance (W, M, C, P). Test and maximum service temperatures are given in the standard.
• Material expectations: seals must be UV resistant and free of defects that affect serviceability.
• Dimensions & tolerances: moulded and extruded seals must meet dimensional tolerance classes referenced to ISO 3302‑1 (e.g., moulding classes M2/M3, extrusion E2).
• Physical performance requirements (specified for preformed seals and sealing compounds), including:
  • Hardness (IRHD) - test per ISO 48 or ISO 7619
  • Tensile strength and elongation at break - ISO 37
  • Compression set - ISO 815 (and ISO 1653 for low temperature)
  • Resistance to heating (accelerated heat exposure per ISO 188 procedure)
  • Volatile loss and condensables after heating
  • Ozone resistance - ISO 1431‑1 (no cracking under defined strain/ozone concentration)
  • Low‑temperature brittleness - ISO 812
• Adhesion testing (Annex A): an accelerated, application‑oriented method using immersion in water, cyclic compression/extension (±25% of joint width) at controlled temperatures, thermal soak steps and repeated cycles to detect bond loss or cohesive failure. Conditioning and sample preparation times are specified (e.g., 14–21 days conditioning).

Applications and users

• Practical uses:
  • Specifying seals for flat-plate and evacuated-tube solar collectors
  • Verifying material suitability for stagnation temperatures, daily thermal cycling, and outdoor exposure
  • Quality control and acceptance testing of preformed seals and sealant compounds
• Typical users:
  • Solar collector manufacturers and component suppliers
  • Material formulators and rubber compounders
  • Test laboratories and certification bodies
  • Design engineers specifying sealing solutions for solar thermal systems

Related standards

• ISO 37, ISO 48, ISO 188, ISO 812, ISO 815, ISO 1431‑1, ISO 3302‑1, ISO 4661, ISO 4892‑2, ISO 877, ISO 471 - referenced for specific test methods and conditioning procedures. These are commonly used together with ISO 9553 when assessing long‑term ageing and weathering.

Keywords: ISO 9553:1997, solar energy, rubber seals, sealing compounds, solar collectors, test methods, adhesion test, compression set, ozone resistance, low‑temperature performance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 9553
First edition
1997-11-01
Solar energy — Methods of testing
preformed rubber seals and sealing
compounds used in collectors
Énergie solaire — Méthodes d’essai des joints préformés en caoutchouc et
des composés pour l’étanchéité utilisés dans les capteurs (DIS distribué en
version anglaise seulement)
Reference number
A
ISO 9953:1997(E)
Contents
1 Scope .1
2 Normative references .1
3 Classification .2
4 Materials .4
5 Dimensions and tolerances .4
6 Physical requirements .4
7 Test methods .7
Annex A — Determination of adhesion of sealing compounds .8
©  ISO 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
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Printed in Switzerland
ii
© ISO
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.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 9953 was prepared by Technical Committe ISO/TC 180, Solar energy.
Annex A forms an integral part of this International Standard.
iii
INTERNATIONAL STANDARD  © ISO ISO 9553:1997(E)
Solar energy — Methods of testing preformed rubber seals
and sealing compounds used in collectors
1 Scope
1.1  This International Standard gives requirements for the classification and testing of rubbers used to seal solar
energy collectors in order to aid selection for specific applications.
NOTE  Particular rubber applications, when specified, may necessitate other requirements that take precedence over these
requirements.
1.2  The design requirements in this International Standard pertain only to permissible deflection of the rubber
during thermal expansion or retraction of the seal in use and to the tolerances on dimensions of moulded and
extruded seals.
1.3  This International Standard does not include requirements pertaining to geometrical design, fabrication or
installation of the seals.
1.4  This International Standard is applicable in conjunction with long-term ageing and weathering tests. However, if
long-term tests are performed, it is recommended that ISO 4892-2 be complied with for ageing tests and ISO 877
for accelerated weathering tests and material exposure tests, respectively.
NOTE  The environmental conditions, test specimen configuration and any test deviations should be agreed upon between the
parties involved. Also, if long-term tests are performed, the specific tests described in this International Standard should be
performed before and after long-term testing is carried out.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 37:1994, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties.
ISO 48:1994, Rubber, vulcanized or thermoplastic — Determination of hardness (hardness between 10 IRHD and 100
IRHD).
1)
ISO 188: – , Rubber, vulcanized — Accelerated ageing and heat-resistance tests.
ISO 471:1995, .
Rubber — Temperatures, humidities, and times for conditioning and testing
ISO 812:1991, Rubber, vulcanized — Determination of low-temperature brittleness.

1)
To be published. (Revision of ISO 188:1982)
© ISO
ISO 815:1991, Rubber, vulcanized or thermoplastic — Determination of compression set at ambient, elevated or low
temperatures.
ISO 877:1994, Plastics—Methods of exposure to direct weathering, to weathering using glass-filtered daylight, and to
intensified weathering by daylight using Fresnel 1 mirrors.
ISO 1431-1:1989, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static strain test.
ISO 3302-1:1996, Rubber — Tolerances for products — Part 1: Dimensional tolerances.
ISO 4632-1:1982, Rubber, vulcanized — Classification system — Part 1: Description of the classification system.
ISO 4661-1:1993, Rubber, vulcanized or thermoplastic — Preparation of samples and test pieces — Part 1: Physical
tests.
ISO 4661-2:1987, Rubber, vulcanized — Preparation of samples and test pieces — Part 2: Chemical tests.
ISO 4892-2:1994, Plastics — Method of exposure to laboratory light sources — Part 2: Xenon-arc sources.
ISO 7619:1997, Rubber — Determination of indentation hardness by means of pocket hardness meters.
3 Classification
3.1 Sealing
Sealing can be accomplished by one of the following methods:
a) a preformed rubber seal (PS);
b) a sealing compound (SC).
NOTE  Sealing compounds should not be used in collectors in which the seal is under mechanical stress.
3.2 Seal type
The following type classification is in accordance with ISO 4632-1. The type selected should be based on the maximum
service temperature which normally occurs when the collector is under stagnation conditions and is receiving the
maximum radiation flux to which it will be exposed.
Table 1 gives the maximum service temperatures and the test temperatures required in tables 3 and 4.
© ISO
Table 1 — Seal types, test temperatures and maximum service temperatures (ISO 4632-1)
Type Test temperature Max. service
temperature
°C
°C
B 100 70
C 125 100
D 150 125
1)
175 150
E
1)
200 175
F
1) 225 200
G
250 225
1)
H
1)
Types E, F, G and H are not required for most solar collectors.
3.3 Seal grade
Table 2 shows differing degrees of rubber hardness in accordance with ISO 48 and ISO 7619. The grade to be
used in a particular application depends on the design of the seal and shall be specified by the designer.
Table 2 — Grade designation for different degrees of hardness
Grade Hardness
3 30 ± 5
4 40 ± 5
5 50 ± 5
6 60 ± 5
7 70 ± 5
8 80 ± 5
3.4 Seal class
3.4.1  The classes shown in table 3 are established based on resistance to low temperatures. The class selected
should be based on the lowest temperature of the collector expected in service.
© ISO
Table 3 — Seal classes, test temperatures and lowest service temperatures
Class Climate Test temperature Lowest service
temperature
°C
°C
W Warm  0 2 10
M Moderate 2 25 2 35
C Cold 2 40 50
P Polar
2 60 2 70
4 Materials
4.1  Seals shall be made from rubber compounds that are resistant to the effect of ultraviolet light and, when
vulcanized as in 7.1, shall comply with the requirements in clause 5.
4.2  Seals shall be free from defects that adversely affect the serviceability of products. Surface texture of
preformed seals should be appropriate to the method of manufacture decided by the parties concerned.
5 Dimensions and tolerances
5.1  Attention should be paid to the effects of seal thermal expansion. For this reason, dimensions will vary greatly
in a solar collector due to the large range of temperatures reached.
–1
NOTE  If the thermal coefficient of linear expansion for the rubber is not known, a value of 0,000 3 K may be assumed for
design purposes.
5.2  The tolerance on dimensions shall conform to the following designations in ISO 3302-1:
5.2.1  Moulded seals
Good quality mouldings (Class M3)
High quality mouldings (Class M2)
5.2.2  Extruded seals
Good quality extrusion (Class E2)
NOTE  The same consideration should be given to shrinkage.
6 Physical requirements
6.1  Preformed seals should conform to the requirements in table 4 when tested by the procedures given in
clause 7.
NOTE  The requirements for low-temperature flexibility and ozone resistance relate to the composition of the rubber
vulcanized (type of rubber and formulation); t
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