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1、BRITISH STANDARD BS EN ISO 291:1997 Plastics Standard atmospheres for conditioning and testing The European Standard EN ISO 291:1997 has the status of a British Standard ICS 83.080.01 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO
2、 291:1997 This British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 October 1997 BSI 03-2000 ISBN 0 580 28585 5 National foreword This British Standard is the E
3、nglish language version of EN ISO 291:1997. It is identical with ISO 291:1997. The UK participation in its preparation was entrusted to Technical Committee PRI/21, Testing of Plastics, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/Eur
4、opean committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary.
5、Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative references to international publications with their corresponding European publications. The British Standards which implement these international or European publications m
6、ay be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British
7、 Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, page 2, the ISO title page, pages
8、ii to iv, pages 1 to 4 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffiel
9、dun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 291:1997 BSI 03-2000i Contents Page National forewordInside front cover Foreword2 Forewordiii Text of ISO 2911 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
10、ii blank Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 291 August 1997 ICS 83.080.10 Descriptors: See ISO document English version Plastics Standard atmospheres for conditioning and
11、testing (ISO 291:1997) Plastiques Atmosphres normales de conditionement et dessai (ISO 291:1997) Kunststoffe Normalklimate fr Konditionierung und Prfung (ISO 291:1997) This European Standard was approved by CEN on 1997-07-26. CEN members are bound to comply with the CEN/CENELEC Internal Regulations
12、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 Central Secretariat or to any CEN member. The European S
13、tandards exist 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 Central Secretariat has the same status as the official versions. CEN members are the national s
14、tandards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Kom
15、itee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 291:1997 E Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontroll
16、ed Copy, (c) BSI EN ISO 291:1997 BSI 03-2000 2 Foreword The text of the International Standard ISO 291:1997 has been prepared by Technical Committee ISO/TC 61 “Plastics” in collaboration with Technical Committee CEN/TC 249 “Plastics”, the secretariat of which is held by IBN. This European Standard s
17、hall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 1998, and conflicting national standards shall be withdrawn at the latest by February 1998. According to the CEN/CENELEC Internal Regulations, the national standar
18、ds organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement n
19、otice The text of the International Standard ISO 291:1997 was approved by CEN as a European Standard without any modification. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GM
20、T+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 291:1997 ii BSI 03-2000 Contents Page Forewordiii 1Scope1 2Definitions1 3Principle1 4Standard atmospheres1 5Classes of standard atmosphere1 6Standard and ambient temperatures2 7Procedure2 Annex A (normative) Attainment of moisture equilibrium by plasti
21、cs in a conditioning atmosphere3 Annex B (informative) Background information3 Table 1 Standard atmospheres1 Table 2 Standard atmosphere classes corresponding to different permitted deviations2 Descriptors: Plastics, tests, artificial weathering tests, testing conditions, test atmospheres, standard
22、atmosphere. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 291:1997 BSI 03-2000iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work
23、 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-governmen
24、tal, 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
25、. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 291 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 6, Ageing, chemical and environmental resistance. This second edition cancels and
26、 replaces the first edition (ISO 291:1977), which has been technically revised. Annex A forms an integral part of this International Standard. Annex B is for information only. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed
27、 Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 291:1997 BSI 03-20001 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
28、 conditions 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 St
29、andard, the following definitions apply: 2.1 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 constitue
30、nts and the atmosphere not being subject to any significant additional radiation influences NOTE 1Standard atmospheres permit a defined state to be attained and maintained for samples or specimens. NOTE 2Standard atmospheres correspond to the average atmospheric conditions in laboratories and can be
31、 established in conditioning (controlled atmosphere) cabinets, chambers or rooms. 2.2 conditioning atmosphere constant atmosphere in which a sample or test specimen is kept before being subjected to test 2.3 test atmosphere constant atmosphere to which a sample or test specimen is exposed throughout
32、 the test 2.4 conditioning one or more operations intended to bring a sample or test specimen into a state of equilibrium with regard to temperature and humidity 2.5 conditioning procedure combination of the conditioning atmosphere and the period of conditioning NOTE 3In this standard the conditioni
33、ng atmosphere and the test atmosphere are usually selected as the standard atmosphere. 2.6 ambient temperature environmental conditions corresponding to the usual atmospheric conditions in laboratories with uncontrolled temperature and humidity 3 Principle If a test specimen is exposed to a specific
34、 conditioning atmosphere or temperature, then a reproducible state of temperature and/or moisture equilibrium is reached between the test specimen and the conditioning atmosphere or temperature. 4 Standard atmospheres Unless otherwise specified, use the conditions given in Table 1 as the standard at
35、mosphere. NOTE 4The values in Table 1 apply to normal altitudes with an atmospheric pressure between 86 kPa and 106 kPa and an air-circulation velocity W 1 m/s. 5 Classes of standard atmosphere Table 2 gives two different classes of standard atmosphere corresponding to different tolerance levels for
36、 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. Table 1 Standard atmosphe
37、res Symbol for standard atmosphere Air temperature t C Relative humidity U % Remarks 23/502350Shall be used unless otherwise specified 27/652765May be used for tropical countries if agreed on by all parties Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled
38、Copy, (c) BSI EN ISO 291:1997 2 BSI 03-2000 Table 2 Standard atmosphere classes corresponding to different permitted deviations NOTE 5Usually, 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
39、temperatures If humidity has no influence or 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, if neither temperature nor humidit
40、y 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”. The phrase “at ambient temperature” refers to an environment the air temperature of wh
41、ich 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 and shall be stated as “at an ambient temperature of 18 C to 28 C”. 7 Procedure 7.1 Conditioning The
42、 period of conditioning shall be stated in the relevant specifications for the material. When the periods are not stated in the appropriate International Standard, the following shall be adopted: a) a minimum of 88 h for atmospheres 23/50 and 27/65; b) a minimum of 4 h for ambient temperatures of 18
43、 C to 28 C. NOTE 6For particular tests and for plastics or test 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). 7.
44、2 Testing Unless otherwise specified, specimens shall be tested 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. Class Permitted deviation
45、 in temperature %t Permitted deviation in relative humidity %U % C23/5027/65 1 155 2 2 10 10 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 20 02:16:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 291:1997 BSI 03-20003 Annex A (normative) Attainment of moisture equilibrium by plastics in a
46、 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 conditioning times given in 7.1 may n
47、ot be satisfactory, especially in the following cases: materials that are known to reach equilibrium with their conditioning atmosphere only after a long period of time (for example, certain polyamides); unfamiliar materials, for which neither the capacity for absorbing moisture nor the time require
48、d 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 change the material (for many materials, a temperature of 50 C 2 C is acceptable); b) condition the speci
49、mens in atmosphere 23/50 until equilibrium has been reached; c) maintain the specimens in an circulating-air oven or conditioning enclosure at a prescribed elevated temperature until moisture equilibrium has 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 certain property values, in particular mechanical ones, are different in the dry state from those obtained after conditioning in atm
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