1、BRITISH STANDARD Wood-based panels - Determination of moisture resistance under cyclic test conditions The European Standard EN 32 1 :200 1 has the status of a British Standard ICs 79.060 BS EN 32 1 :2002 present to the responsible European committee any enquiries on the interpretation, or proposals
2、 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. Cross-references The British Standards which implement internat
3、ional or European publications referred to in this document may 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
4、 all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. This British Standard. havinp. - been prepared under the direction of the Sector Policy
5、 and Stratenv Committee for Summary Of pages This document comprises a front cover, an inside front cover, the EN title page, Building gd Civil under the authoritv of the pages 2 to 8, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the Enginee
6、ring, was published Standards Policy and Strategy Committee on 28 January 2002 document was last issued. O BSI 28 January 2002 ISBN O 580 38913 8 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 321 November 2001 ICs 79.060.01 Supersedes EN 321:1993 English version Wood-based panels - Determinat
7、ion of moisture resistance under cyclic test conditions Panneaux base de bois - Dtermination de la rsistance lhumidit selon essais cycliques Holzwerkstoffe - Bestimmung der Feuchtebestndigkeit durch Zyklustest This European Standard was approved by CEN on 30 September 2001. CEN members are bound to
8、comply with the CENKENELEC 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 Manageme
9、nt 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 Management Centre has the same status as the offi
10、cial versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION EUROP
11、ISCHES KOMITEE FR NORMUNG COMIT EUROPEN DE NORMALISATION Management Centre: rue de Stassart, 36 B-1050 Brussels O 2001 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 321:2001 E EN 321:2001 (E) Contents Page Foreword . 3 1 Scope .
12、4 3 Principle 4 4 Apparatus 4 6 Procedure 5 8 Testreport . 7 8 2 Normative references 4 5 Testpieces . 5 7 Expression of results 7 Bibliography . 2 EN 321:2001 (E) Foreword This European Standard has been prepared by Technical Committee CEN/TC 112 “Wood-based panels“, the secretariat of which is hel
13、d by DIN. 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 May 2002, and conflicting national standards shall be withdrawn at the latest by May 2002. This European Standard supersedes EN 321 :I 993
14、. This standard is one of a series specifying methods of test for determining the behaviour of wood-based panels under the influence of moisture. This standard is a revised version of EN 321:1993 and AC:1994. Compared to the version EN 321:1993 and AC:I 994 the following modifications have been made
15、: a) The scope has been extended from fibreboards to wood-based panels. b) The method has been described in more detail in order to avoid misinterpretation and improve reproducibility. According to the CENKENELEC Internal Regulations, the national standards organizations of the following countries a
16、re 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. 3 EN 321:2001 (E) 1 Scope This European Standard specifies
17、 a test method for the determination of the moisture resistance of wood-based panels under cyclic test conditions. 2 Normative references This European Standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate pl
18、aces in the text, and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication r
19、eferred to applies (including amendments). EN 31 O, Wood based panels - Determination of modulus of elasticity in bending and of bending strength. EN 31 7, Particleboards and fibreboards - Determination of swelling in thickness after immersion in water. EN 31 9, Particleboards and fibreboards - Dete
20、rmination of tensile strength perpendicular to the plane of the board. EN 325, Wood based panels - Determination of dimensions of test pieces. EN 326-1, Wood based panels - Sampling, cutting and inspection - Part I: Sampling and cutting of test pieces and expression of test results. 3 Principle Test
21、 pieces are exposed to three cycles, each comprising immersion in water, freezing, and drying at elevated temperature. After cyclic treatment, the test pieces are then reconditioned and their swelling in thickness and residual strength determined. 4 Apparatus 4.1 Water bath A water bath which shall
22、maintain water at a temperature of (20 f 1) “C. 4.2 Freezing cabinet A freezing cabinet which shall be capable of maintaining a temperature of between - 12 “C and - 25 “C. It shall also be capable of regaining this temperature within 1 h after inserting the test pieces. 4.3 Drying cabinet A laborato
23、ry drying cabinet with forced, evenly distributed air ventilation, which shall maintain a temperature of (70 f 2) “C and have (25 f 5) air exchanges per hour. It shall be capable of reaching a temperature of (70 f 2) “C within 2 h after inserting the test pieces. 4 EN 321:2001 (E) 5 Test pieces 5.1
24、Sampling Sampling and cutting of the test pieces shall be carried out according to EN 326-1 and the relevant material specification standard. 5.2 Dimensions of test pieces Dimensions shall be in accordance with EN 310, EN 317 and EN 319 as appropriate. 5.3 Conditioning The test pieces shall be condi
25、tioned to constant mass in an atmosphere with a relative humidity of (65 f 5) % and a temperature of (20 f 2) OC. Constant mass is considered to be reached when the results of two successive weighing operations, carried out at an interval of 24 h, do not differ by more than 0,l % of the mass of each
26、 test piece. 6 Procedure 6.1 Treatment of the test pieces The following sequence of operations shall be carried out: 6.1 .I Initial conditioning and measurement 1) Condition the test pieces in accordance with 5.3. 2) Determine the dimensions of the test pieces in accordance with EN 325. 6.1.2 Cyclic
27、 treatment 6.1.2.1 First cycle 3) Immerse the test pieces in the water bath which shall contain fresh water of pH = (7 f 1) and be at a tempera- ture of (20 f 1) OC. The test pieces shall be placed standing on one edge (one long edge in the case of the bending test pieces) and shall be separated fro
28、m each other, and from the bottom and sides of the water bath by at least 15 mm. The upper edges of test pieces shall be covered by (25 f 5) mm of water throughout the immersion period. The immersion period shall be (70 f 1) h. 4) Remove the test pieces from the water bath. Allow the surface water t
29、o drain off for a few minutes and then place the test pieces in the freezing cabinet which shall be at a temperature between - 12 OC and - 25 OC. The test pieces shall be placed standing on the same edge as when immersed, and shall be separated from each other by at least 15 mm. The freezing period
30、shall be (24 f 1) h. 5) Remove the test pieces from the freezing cabinet and immediately place them in the drying cabinet which shall be at a temperature of (70 f 2) OC. The test pieces shall be placed standing on the same edges as when immersed and frozen, and shall be separated from each other by
31、at least 15 mm. The total volume of the test pieces shall not exceed 10 % of the internal volume of the drying cabinet. 5 EN 321:2001 (E) The drying period shall be (70 f 1) h. 6) Remove the test pieces from the drying cabinet and place them in a room at a temperature of (20 f 5) OC. The test piece
32、shall be placed standing on the same edge as when immersed, frozen and dried, and shall be separated from each other by at least 15 mm. The cooling period shall be (4 f 0,5) h. 6.1.2.2 Second cycle 7) At the end of the cooling period immerse the test pieces again in the water bath which shall contai
33、n fresh water of pH = (7 f 1) and be at a temperature of (20 f 1) OC. Before standing them in the water bath, the test pieces shall be inverted to stand on its opposite edge. The test pieces shall be separated from each other and from the bottom and sides of the bath by at least 15 mm. The upper edg
34、es of test pieces shall be covered by (25 f 5) mm of water throughout the immersion period. The immersion period shall be (70 f 1) h. 8) Remove the test pieces from the water bath. Allow the surface water to drain off for a few minutes and then place the test pieces in the freezing cabinet which sha
35、ll be at a temperature between - 12 OC and - 25 OC. The test pieces shall be placed standing on the same edges as when immersed (7), and shall be separated from each other by at least 15 mm. The freezing period shall be (24 f 1) h. 9) Remove the test pieces from the freezing cabinet and immediately
36、place them in the drying cabinet which shall be at a temperature of (70 f 2) OC. The test pieces shall be placed standing on the same edge as when immersed (7) and frozen (8), and shall be separated from each other by at least 15 mm. The total volume of the test pieces shall not exceed 10 % of the i
37、nternal volume of the drying cabinet. The drying period shall be (70 f 1) h. 1 O) Remove the test pieces from the drying cabinet and place them in a room with a temperature of (20 f 5) OC. The test piece shall be placed on the same edge as when immersed (7), frozen (8) and dried (9), and shall be se
38、parated from each other by at least 15 mm. The cooling period shall be for (4 f 0,5) h. 6.1.2.3 Third cycle 11) At the end of the cooling period immerse the test pieces again in the water bath which shall contain fresh water of pH = (7 f 1) and be at a temperature of (20 f 1) OC. Before standing the
39、m in the water bath, the test pieces shall be inverted to stand on its opposite edge (.e. each test piece shall be standing on the same edge as during the initial immersion period described in 3). The test pieces shall be separated from each other and from the bottom and sides of the bath by at leas
40、t 15 mm. The upper edges of test pieces shall be covered by (25 f 5) mm of water throughout the immersion period. The immersion period shall be (70 f 1) h. 12) Remove the test pieces from the water bath. Allow the surface water to drain off for a few minutes and then place the test pieces in the fre
41、ezing cabinet which shall be at a temperature between - 12 OC and - 25 OC. 6 EN 321:2001 (E) The test pieces shall be placed standing on the same edge as when immersed (1 I), and shall be separated from each other by at least 15 mm. The freezing period shall be (24 f 1) h. 13) Remove the test pieces
42、 from the freezing cabinet and immediately place them in the drying cabinet which shall be at a temperature of (70 f 2) OC. The test pieces shall be placed standing on the same edge as when immersed (1 1) and frozen (12), and shall be separated from each other by at least 15 mm. The total volume of
43、the test pieces shall not exceed 10 % of the internal volume of the drying cabinet. The drying period shall be (70 f 1) h. NOTE Stages 3 to 13 above take approximately 500 h to complete. 6.1.3 Reconditioning 14) Remove the test piece from the drying cabinet and condition them to constant mass. 15) D
44、etermine the dimensions of the test pieces in accordance with EN 325. 6.2 Determination of swelling in thickness Determine the swelling in thickness of the test pieces after cyclic test according to EN 317. 6.3 Determination of tensile strength perpendicular to the plane of the board Determine the t
45、ensile strength perpendicular to the plane of the board according to EN 319 using the dimensions determined in 6.1 .I. NOTE Before bonding the test pieces to the loading blocks, their faces may be lightly sanded to remove any roughness caused by the cyclic test. 6.4 Determination of bending strength
46、 When required, determine the bending strength according to EN 310 using the dimensions of the test pieces after either initial (6.1 .I) or final (6.1.3) conditioning depending on the requirements of the relevant specification. 7 Expression of results 7.1 Swelling in thickness According to EN 317. 7
47、.2 Tensile strength According to EN 319. 7.3 Bending strength According to EN 310. The method of calculation used shall be stated in the report. 8 Test report According to EN 326-1. 7 EN 321:2001 (E) Bibliography EN 300, Oriented Strand Boards (OSB) - Definitions, classification and specifications.
48、EN 312-5, Particleboards - Specifications - Part 5: Requirements for loadbearing boards for use in humid conditions. EN 312-7, Particleboards - Specifications - Part 7: Requirements for heavy duty load bearing boards for use in humid conditions. EN 622-5, Fibreboards - Specifications - Part 5: Requi
49、rements for dry process boards (MDF). EN 634-2, Cement bonded particleboards - Specifications - Part 2: Requirements for OPC bonded particleboards for use in dry, humid and exterior conditions. 8 BS EN 32 1 :2002 B SI 3 89 Chiswick High Road London W4 4AL BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess th
