1、August 2008DEUTSCHE NORM English price group 8No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 83.080.01!$QNT“1464349ww
2、w.din.deDDIN EN ISO 291Plastics Standard atmospheres for conditioning and testing (ISO 291:2008)English version of DIN EN ISO 291:2008-08Kunststoffe Normalklimate fr Konditionierung und Prfung (ISO 291:2008)Englische Fassung DIN EN ISO 291:2008-08SupersedesDIN EN ISO 291:2006-02www.beuth.deDocument
3、comprises 13 pagesDIN EN ISO 291:2008-08 2 National foreword This standard has been prepared by Technical Committee ISO/TC 61 “Plastics” in collaboration with Technical Committee CEN/TC 249 “Plastics” (Secretariat: NBN, Belgium). The responsible German body involved in its preparation was the Normen
4、ausschuss Kunststoffe (Plastics Standards Committee), Technical Committee NA 054-01-04 AA Verhalten gegen Umgebungseinflsse. The DIN Standard corresponding to the International Standard referred to in clause 2 of the EN ISO is as follows: ISO 62 DIN EN ISO 62 Amendments This standard differs from DI
5、N EN ISO 291:2006-02 as follows: a) In Table 1, the way in which the two standard atmospheres are used is now described in terms of nontropical and tropical countries. b) A second note, concerning the unacceptability of wider tolerances on temperature and relative humidity, has been added at the end
6、 of clause 6. Previous editions DIN EN 62: 1977-11 DIN EN ISO 291: 1997-11, 2006-02 National Annex NA (informative) Bibliography DIN EN ISO 62, Plastics Determination of water absorption EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 291May 2008ICS 83.080.01 Supersedes EN ISO 291:2005 English
7、 VersionPlastics - Standard atmospheres for conditioning and testing(ISO 291:2008)Plastiques - Atmosphres normales de conditionnement etdessai (ISO 291:2008)Kunststoffe - Normalklimate fr Konditionierung undPrfung (ISO 291:2008)This European Standard was approved by CEN on 21 April 2008.CEN members
8、are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to
9、the CEN 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same
10、status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania
11、, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldw
12、ide for CEN national Members.Ref. No. EN ISO 291:2008: E2 EN ISO 291:2008 (E) DIN EN ISO 291:2008-08 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle5 5 Standard atmosphere5 6 Classes of standard atmosphere .5 7 Standard and ambient temperatures .6 8
13、Procedure .6 Annex A (normative) Attainment of moisture equilibrium by plastics in a conditioning atmosphere.7 Annex B (informative) Background information 9 Bibliography. 11 3 EN ISO 291:2008 (E) DIN EN ISO 291:2008-08 Foreword This document (EN ISO 291:2008) has been prepared by Technical Committe
14、e ISO/TC 61 “Plastics“ in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by NBN. 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 November 2008, and c
15、onflicting national standards shall be withdrawn at the latest by November 2008. 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
16、document supersedes EN ISO 291:2005. 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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greec
17、e, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 291:2008 has been approved by CEN as a EN ISO 291:2008 without any modi
18、fication. 1 Scope This International Standard sets out specifications relating to the conditioning and testing of all plastics and all types of test specimen at constant atmospheric conditions. Special atmospheres applicable to a particular test or material or simulating a particular climatic enviro
19、nment are not included in this International Standard. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (includ
20、ing any amendments) applies. ISO 62, Plastics Determination of water absorption 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 standard atmosphere preferred constant atmosphere for which specific air temperature and humidity values, as well
21、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 a
22、nd 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. 3.2 conditioning atmosphere constant atmosphere in which a sample or test s
23、pecimen is kept before being subjected to a test 3.3 test atmosphere constant atmosphere to which a sample or test specimen is exposed throughout a test 3.4 conditioning one or more operations intended to bring a sample or test specimen into a state of equilibrium with regard to temperature and humi
24、dity 3.5 conditioning procedure combination of the conditioning atmosphere and the period of conditioning 4 EN ISO 291:2008 (E) DIN EN ISO 291:2008-08 3.6 ambient temperature environmental conditions corresponding to the usual atmospheric conditions in laboratories with uncontrolled temperature and
25、humidity NOTE The phrase “at ambient temperature” refers to an environment the air temperature of which lies within a specified range, no consideration being given to relative humidity, atmospheric pressure or air-circulation velocity. In general, the air-temperature range extends from 18 C to 28 C
26、and is stated as “at an ambient temperature of 18 C to 28 C”. 4 Principle If a test specimen is exposed to a specific conditioning atmosphere or temperature, then a reproducible state of temperature and/or of moisture equilibrium is reached between the test specimen and the conditioning atmosphere o
27、r temperature. It is not the intent of this International Standard to define procedures specifying how to determine sensitivity to moisture. Some materials may have special conditioning requirements. Follow the relevant International Standards. 5 Standard atmosphere Unless otherwise specified, use o
28、ne of the sets of conditions given in Table 1 as the standard atmosphere. Table 1 Standard atmospheres Air temperature Relative humidity (RH) Symbol for standard atmosphere C % Remarksa23/50 23 50 For non-tropical countries 27/65 27 65 For tropical countries aWhen obtaining comparative data on polym
29、ers, e.g. for databases, standard atmosphere 23/50 shall be used. NOTE The values in Table 1 apply to normal altitudes with an atmospheric pressure between 86 kPa and 106 kPa and an air-circulation velocity u 1 m/s. 6 Classes of standard atmosphere Table 2 gives the different classes of standard atm
30、osphere corresponding to different tolerance levels for the temperature and relative humidity. The tolerances given in Table 2 apply to the specimen-storage space in a test enclosure or conditioning enclosure. Class 1 cabinets will require more frequent calibration. Follow the manufacturers recommen
31、dations for calibration. Cabinets shall be calibrated at least once per year. 5 EN ISO 291:2008 (E) DIN EN ISO 291:2008-08 Table 2 Standard atmosphere classes corresponding to different permitted deviations Permitted deviations in relative humidity (RH) % Class Permitted deviations in temperature C
32、23/50 27/65 1 1 5 5 2 2 10 10 NOTE 1 Usually, the tolerances are coupled in pairs, i.e. class 1 tolerance for both temperature and relative humidity or class 2 tolerance for both. NOTE 2 Atmospheres with broader tolerances on temperature and relative humidity cannot be considered as constant atmosph
33、eres. 7 Standard and ambient temperatures If humidity has no influence or only a negligible influence on the properties being examined, the relative humidity does not have to be controlled. The corresponding environments are designated “temperature 23” and “temperature 27”, respectively. Similarly,
34、if neither temperature nor humidity has any noticeable influence on the properties being examined, neither the temperature nor the relative humidity has to be controlled. In this case, the atmospheric condition is termed the “ambient temperature”. 8 Procedure 8.1 Conditioning The period of condition
35、ing shall be as stated in the relevant specifications for the material. When the conditioning periods are not stated in the applicable standard, the following shall be adopted: a) unless otherwise specified, a minimum of 88 h for atmospheres 23/50 and 27/65; b) unless otherwise specified, a minimum
36、of 4 h for temperatures of 18 C to 28 C. NOTE 1 The length of time necessary for a plastics material to come to humidity equilibrium is in general much longer than the length of time necessary for it to come to temperature equilibrium. NOTE 2 Samples conditioned in accordance with a) may not reach h
37、umidity equilibrium. A sufficient equilibrium is reached after conditioning longer than the time t70as defined in ISO 62. t70depends on the square of the thickness. More information about the time needed to reach equilibrium can be found in Annex A. NOTE 3 For particular tests and for plastics or te
38、st specimens that are known to reach temperature and humidity equilibrium either very rapidly or very slowly, a shorter or longer time may be specified for the conditioning period in the appropriate International Standard (see Annex A). 8.2 Testing Unless otherwise specified, specimens shall be test
39、ed in the same atmosphere or at the same temperature in which they have been conditioned. In all cases, the test shall be carried out immediately after the removal of the specimens from the conditioning enclosure. 6 EN ISO 291:2008 (E) DIN EN ISO 291:2008-08 Annex A (normative) Attainment of moistur
40、e equilibrium by plastics in a conditioning atmosphere The amount of moisture absorbed by a test specimen conditioned in an atmosphere and the rate of moisture absorption or desorption vary significantly depending on the nature and the shape of the material of which the specimen is made. The conditi
41、oning times given in 8.1 may not be satisfactory, especially in the following cases: specimen materials and specimen thicknesses that are known to reach equilibrium with their conditioning atmosphere only after a long period of time (for example, certain polyamides and thicknesses over 2 mm, see ISO
42、 62); unfamiliar materials, for which neither the capacity for absorbing moisture nor the time required to reach equilibrium can be estimated beforehand. In these cases, use one of the following procedures: a) Dry the material at an elevated temperature that will not significantly or permanently cha
43、nge the material (for many materials, a temperature of 50 C 2 C is acceptable). Allow the specimens at least 2 h to cool to the test temperature in a desiccator. State in the test report that the conditioning did not conform to ISO 291 but was a recommended alternative for special cases. b) Conditio
44、n the specimens in atmosphere 23/50 or 27/65 until equilibrium has, to all intents and purposes, been reached. A sufficient time is the time t70at which 70 % of the water content at saturation is reached, as defined in ISO 62. If the time t70as defined in ISO 62 corresponds to a specimen of thicknes
45、s d0, calculate the conditioning time t70necessary for specimens of other thicknesses using Equation (A.1): 270 7020dttd = (A.1) where t70is the conditioning time necessary; t70is the time taken for moisture equilibrium to be reached, determined in accordance with ISO 62, with specimens of thickness
46、 d0; d is the thickness of the specimens to be conditioned in accordance with this International Standard. Mention this in the test report. c) Keep the specimens in a circulating-air oven or conditioning enclosure at a prescribed elevated temperature and defined humidity (preferred are 50 % RH or 65
47、 % RH) until moisture equilibrium has, to all intents and purposes, been reached (the temperature and relative humidity used shall be agreed upon by all interested parties and shall be included in the test report). Procedure a) has the disadvantage that the values of certain properties, in particula
48、r mechanical properties, are different in the dry state from those obtained after conditioning in atmosphere 23/50 or 27/65. It is for this reason that this conditioning procedure does not conform to ISO 291 but is a recommended alternative. 7 EN ISO 291:2008 (E) DIN EN ISO 291:2008-08 In the case o
49、f procedure b), the following rule of thumb may be useful: equilibrium can be assumed to have been reached if two weighings made at an interval of d 2weeks differ by only 0,1 % (d being the thickness, in millimetres, of the specimen). Procedure c) is used when the moisture diffusion characteristics of the polymer are known and can be used to determine appropriate exposure periods and conditions. The specimens shall be kept in the oven or conditioning enclosure until they are, to all intents and purposes, in a state of moisture e
