EN ISO 291:1997

SLOVENSKI STANDARD
SIST EN ISO 291:1999
01-maj-1999
Polimerni materiali – Standardne atmosfere za kondicioniranje in preskušanje (ISO
291:1997)
Plastics - Standard atmospheres for conditioning and testing (ISO 291:1997)
Kunststoffe - Normalklimate für Konditionierung und Prüfung (ISO 291:1997)
Plastiques - Atmospheres normales de conditionnement et d'essai (ISO 291:1997)
Ta slovenski standard je istoveten z: EN ISO 291:1997
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 291:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 291:1999

---------------------- Page: 2 ----------------------

SIST EN ISO 291:1999

---------------------- Page: 3 ----------------------

SIST EN ISO 291:1999

---------------------- Page: 4 ----------------------

SIST EN ISO 291:1999
INTERNATIONAL
IS0
STANDARD
291
Second edition
1997-08-01
Plastics - Standard atmospheres
for conditioning and testing
- A tmosphkres normales de conditionnement et d’essai
Plastiques
Reference number
IS0 291:1997(E)

---------------------- Page: 5 ----------------------

SIST EN ISO 291:1999
IS0 291 :1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
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 IS0 291 was prepared by Technical Committee
ISO/TC 61, Plastics, Subcommittee SC 6, Ageing, chemical and
environmental resistance.
This second edition cancels and replaces the first edition
(IS0 291:1977), which has been technically revised.
Annex A forms an integral part of this International Standard. Annex B is for
information only.
0 IS0 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 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
x.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii

---------------------- Page: 6 ----------------------

SIST EN ISO 291:1999
IS0 291:1997(E)
INTERNATIONAL STANDARD @ Iso
Plastics - Standard atmospheres for conditioning
and testing
1 Scope
This International Standard sets out specifications relating to the conditioning and
testing of all plastics and all types of test specimens at constant atmospheric condi-
tions which correspond to the average atmospheric conditions in laboratories.
Special atmospheres applicable to a particular test or material or simulating a
particular climatic environment are not included in this International Standard.
2 Definitions
For the purposes of this International Standard, the following definitions apply:
21 . standard atmosphere
Preferred constant atmosphere for which specific air temperature and humidity
values, as well as limit ranges for atmospheric pressure and air-circulation velocity,
are specified, the air not having any significant additional constituents and the
atmosphere not being subject to any significant additional radiation influences.
NOTE 1: Standard atmospheres permit a defined state to be attained and
maintained for samples or specimens.
NOTE 2: Standard atmospheres correspond to the average atmospheric
conditions in laboratories and can be established in conditioning
(controlled atmosphere) cabinets, chambers or rooms.
. conditioning atmosphere
22
Constant atmosphere in which a sample or test specimen is kept before being
subjected to test.
23 . test atmosphere
Constant atmosphere to which a sample or test specimen is exposed throughout
the test.
.
24 conditioning
One or more operations intended to bring a sample or test specimen into a state of
equilibrium with regard to temperature and humidity.

---------------------- Page: 7 ----------------------

SIST EN ISO 291:1999
IS0 291:1997(E) @ IS0
25 . conditioning procedure
Combination of the conditioning atmosphere and the period of conditioning.
NOTE 3: In this standard the conditioning atmosphere and the
test atmosphere are usually selected as the standard atmosphere.
26 . ambient temperature
Environmental conditions corresponding to the usual atmospheric conditions in
laboratories with uncontrolled temperature and humidity.
Principle
If a test specimen is exposed to a specific conditioning atmosphere or temperature,
then a reproducible state of temperature and/or moisture equilibrium is reached bet-
ween the test specimen and the conditioning atmosphere or temperature.
Standard atmospheres
Unless otherwise specified, use the conditions given in table 1 as the standard
atmosphere.
Table 1 - Standard atmospheres
.
Aw Relative
Symbol for
Remarks
temperature humidity
standard
t lJ
atmosphere 0
0
/ 0
C
23 50 Shall be used unless otherwise
23150
specified
27 65 May be used for tropical countries
27165
if agreed on by all parties
NOTE 4: The values in table 1 apply to normal altitudes with an atmospheric
pressure between 86 kPa and 106 kPa and an air-circulation
velocity 2 1 m/s.
Classes of standard atmosphere
Table 2 gives two different classes of standard atmosphere corresponding to
different tolerance levels for the temperature and relative humidity. The tolerances
given in table 2 apply to the specimen-stowage space in a test enclosure or
conditioning enclosure and include deviations both with respect to time and with
respect to the position of the test specimen in the enclosure.

---------------------- Page: 8 ----------------------

SIST EN ISO 291:1999
IS0 291:1997(E)
@ IS0
Table 2 - Standard atmosphere classes corresponding to different permitted
deviations
Permitted Permitted deviation in relative humidity
deviation in
AU
0
temperature
0
/
At
0
23/50
C 27165
I
*l
*5 -
I +5
*2
I *lO +I0
NOTE 5: Usually, the tolerances are coupled in pairs, i.e. class 1 tolerance for
both temperature and relative humidity or class 2 tolerance for both.
6 Standard and ambient temperatures
If humidity has no influence or a negligible influence on the properties being
examined, the relative
...