CEN TS 16818-2018 Durability of wood and wood-based products - Moisture dynamics of wood and wood-based products.pdf

1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Durability of wood and wood-based products - Moisture dynamics of wood and wood-based productsPD CEN/TS 16818:2018National forewordThis Published Document is the UK implementation of CEN/TS 16818:2018.The UK participati

2、on in its preparation was entrusted to Technical Committee B/515, Wood preservation.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its

3、 correct application. The British Standards Institution 2018 Published by BSI Standards Limited 2018ISBN 978 0 580 88432 0ICS 79.080Compliance with a British Standard cannot confer immunity from legal obligations.This Published Document was published under the authority of the Standards Policy and S

4、trategy Committee on 31 August 2018.Amendments/corrigenda issued since publicationDate Text affectedPUBLISHED DOCUMENTPD CEN/TS 16818:2018TECHNICAL SPECIFICATIONSPCIFICATION TECHNIQUETECHNISCHE SPEZIFIKATIONCEN/TS 16818August 2018ICS 79.080EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMA

5、LISATIONEUROPISCHES KOMITEE FR NORMUNGCEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2018 CEN Ref. No. CEN/TS 16818:2018: EAll rights of exploitation in any form and by any means reserved worldwide for CEN national MembersDurability of wood and wood-based products - Moisture dynami

6、cs of wood and wood-based productsDurabilit du bois et des matriaux base de bois - Cintique dhumidification du bois et des produits base de boisDauerhaftigkeit von Holz und Holzprodukten - Feuchte-Dynamik von Holz und HolzproduktenThis Technical Specification (CEN/TS) was approved by CEN on 2 March

7、2018 for provisional application.The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.CEN members are require

8、d to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS) until the final decision about the possible conver

9、sion of the CEN/TS into an EN is reached.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxem

10、bourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.English VersionCEN/TS 16818:2018 (E)European foreword iiiIntroduction iv1 Scope . 52 Normative references 53 Terms and definitions . 54 Principle 55 Test sp

11、ecimens 65.1 Quality 65.2 Provision of the test specimens (Annex A) . 65.3 Dimensions of each test specimen . 65.3.1 Floating test 65.3.2 Submersion test 65.4 Number of test specimens . 65.5 Products and reagents 65.5.1 Water 65.5.2 End sealer 65.6 Apparatus 66 Procedure. 76.1 Treatment of the wood

12、test specimens 76.1.1 Sealing of the end grain and edges . 76.1.2 Conditioning of test specimens . 76.2 Absorption cycle 76.2.1 Floating test 76.2.2 Submersion test 86.3 Desorption cycle 86.4 Additional short-term absorption cycle 86.5 Oven dry mass . 97 Calculation and reporting results . 97.1 Abso

13、rption coefficient 97.2 Residual moisture 108 Test report 12Annex A (informative) Production of treatment blocks 13Annex B (informative) Example of a test report 15Bibliography .16iiContents PagePD CEN/TS 16818:2018CEN/TS 16818:2018 (E)European forewordThis document (CEN/TS 16818:2018) has been prep

14、ared by Technical Committee CEN/TC 38 “Durability of wood and wood-based products”, the secretariat of which is held by AFNOR.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or

15、 all such patent rights.According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Repub

16、lic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.iiiPD CEN/TS 16818:2018CEN/TS 16818:2018 (E)Introdu

17、ctionMoisture has a significant influence on the mechanical and physical properties and on the biological durability of wood and wood-based materials. The test method described in this Technical Specification is a laboratory method in which small samples are exposed to water. It provides a basis for

18、 assessment of the moisture dynamics of wood and wood-based materials in service. The method permits the determination of the water uptake and moisture release which may provide important information on the susceptibility to the onset of fungal attack in certain end uses.It is recommended that the r

19、esults of this test should be supplemented by further suitable tests and especially by practical experience.ivPD CEN/TS 16818:2018CEN/TS 16818:2018 (E)1 ScopeThis document details a method for determining the water uptake and the effectiveness of the drying process on solid wood, wood-based material

20、s or coated wood by means of water absorption and water vapour desorption. This document lays down a method to assess the moisture dynamics of wooden products which can be a contributing factor to the susceptibility to wood decay.2 Normative referencesThe following documents are referred to in the t

21、ext in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.EN ISO 3696, Water for analytical laboratory u

22、se Specification and test methods (ISO 3696)EN 13183-1, Moisture content of a piece of sawn timber Part 1: Determination by oven dry method3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.ISO and IEC maintain terminological databases for use in stan

23、dardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp 3.1suppliersponsor of the test (person or company providing the samples or wood-based products to be tested)3.2residuemoisture content l

24、eft in the test specimen after desorption as a percentage of the absorbed moisture3.3residual moisture contentincrease in moisture content in the test specimen after desorption3.4absorption coefficientslope of the fitted line for a plot of the water uptake per square metre against the square root of

25、 the elapsed time3.5treatment blockwood or wood-based product that is subsequently edge and end grain sealed to create the test specimen4 PrincipleTest specimens prepared from the wood or wood-based product under test are exposed to water by means of floating or submersion. During a prescribed wetti

26、ng and drying period under defined conditions the mass of the specimens is registered. The mass gain and mass loss is used to estimate the residual moisture and thus the potential to reach and remain at a moisture content at which fungal decay can occur.5PD CEN/TS 16818:2018CEN/TS 16818:2018 (E)5 Te

27、st specimens5.1 QualityThe wood and wooden products shall be free from cracks, stain, decay, insect damage or other defect. In case of timber, it shall be quarter sawn for provision of test specimens.5.2 Provision of the test specimens (Annex A)Condition the wood and wooden products at (65 5) % and

28、(20 2) C to constant mass (mass variation in consecutive measurements 0,01 g). Prepare planed strips having a cross section of (50 0,5) mm and (25 0,5) mm. The longitudinal faces of the wood samples shall be parallel to the direction of the grain. The annual rings shall not be parallel to the faces

29、(contact angle 10) but otherwise can run in any other direction. Make transverse cuts, neatly to give sharp edges and a fine-sawn finish to the end grain surfaces, to give test specimens a length of (50 0,5) mm for the floating test method or a length of (150 0,5) mm long for the submersion test met

30、hod.The test specimens shall originate from a minimum of three planks or panels.5.3 Dimensions of each test specimen5.3.1 Floating testThe dimension of each test specimen at conditioned mass shall be (50 0,5) mm (50 0,5) mm (25 0,5) mm or the thickness of the panel under test.5.3.2 Submersion testTh

31、e dimension of each test specimen at conditioned mass shall be (150 0,5) mm (50 0,5) mm (25 0,5) mm or the thickness of the panel under test.5.4 Number of test specimensUse at least three test specimens per plank or panel. This results in a minimum total of 9 test specimens.5.5 Products and reagents

32、5.5.1 WaterComplying with grade 3 of EN ISO 3696.5.5.2 End sealerThe end sealer is necessary to prevent water penetrating along the end grain. A two pack polyurethane finish (e.g. Sigmadur 520 (HB Finish)1)or any appropriate material which is water resistant.5.6 Apparatus5.6.1 Conditioning room well

33、 ventilated and controlled at (20 2) C and (65 5) % relative humidity.5.6.2 Saw with blades giving a fine-sawn finish.1) Sigmadur 520 (HB Finish) is the trade name of a product supplied by Sigma Coatings. This information is given for the convenience of users of this Technical Specification and does

34、 not constitute an endorsement by CEN/TC 38 of the product named. Equivalent products may be used if they can be shown to lead to the same results.6 PD CEN/TS 16818:2018CEN/TS 16818:2018 (E)5.6.3 Test containers for demineralized water, of sufficient size to hold the specimens under test.5.6.4 Usual

35、 laboratory equipment, especially: analytical balance with accuracy of 0,01 g; various brushes; drying oven, adjustable at (103 2) C; desiccator, with efficient desiccant (e.g. silica gel).6 Procedure6.1 Treatment of the wood test specimens6.1.1 Sealing of the end grain and edgesThe end grains and e

36、dges of the specimens are sealed by means of a paint roller using a two pack polyurethane finish (see 5.5.2) or a product with demonstrably similar performance. This is repeated three times with drying between each application, ensuring an adequate sealing of the edges. The surfaces are left uncoate

37、d.NOTE To ensure adequate end sealing, it can be useful to apply the end sealer and overlap the edges 1 mm to 2 mm, e.g. by using a short dip of the cross sections in the sealant.6.1.2 Conditioning of test specimensThe specimens are stored in a conditioning room (see 5.6.1) until a stable mass is ac

38、hieved (mass variation in consecutive measurements 0,01 g).6.2 Absorption cycle6.2.1 Floating testWeigh the test specimens to the nearest 0,01 g and record the initial mass (mi).Fill a container with demineralized water (5.5.1) and place in the conditioning room (5.6.1).Place the test specimens face

39、 down on the water surface ensuring that the lower sample face is fully submerged. If the test specimens sink, put a tray with a non-corrodible metal mesh bottom in the container to sit approximately 10 mm below the surface of the water. The tray should support the specimens so the lower test face i

40、s fully submerged under the water level and the upper face is not submerged.After 1 h, remove the first test specimen from the water. Blot lightly to remove water droplets and weigh. Record the elapsed time (x) and mass to the nearest 0,01 g (mx). Put the test specimen back, face down on the water s

41、urface. Repeat for the second test specimen and so on until all individual specimen data are recorded.Repeat this after 4 h, 8 h, 24 h, 48 h, 72 h and 144 h.All handling of the test specimens should be carried out in the conditioning room (5.6.1) as quickly as possible to minimize any disturbance.Co

42、nsidering the specific time intervals at which data are recorded it is recommended to start the experiment at 09:00 on a Tuesday.7PD CEN/TS 16818:2018CEN/TS 16818:2018 (E)6.2.2 Submersion testWeigh the test specimens to the nearest 0,01g and record the initial mass (mi).Fill a container with deminer

43、alized water (5.5.1) and place in the conditioning room (5.6.1).Place the test specimens in the water ensuring that the sample is fully submerged and put a tray with non-corrodible metal mesh on top of the specimens to prevent the specimens from floating.After 1 h, remove the first test specimen fro

44、m the water. Blot lightly to remove water droplets and weigh. Record the elapsed time (x) and mass to the nearest 0,01 g (mx). Put the test specimen back in the water. Repeat for the second test specimen and so on until all individual specimen data are recorded.Repeat this after 4 h, 8 h, 24 h, 48 h

45、, 72 h and 144 h.All handling of the test specimens should be carried out in the conditioning room (5.6.1) as quickly as possible to minimize any disturbance.Considering the specific time intervals at which data are recorded it is recommended to start the experiment at 09:00 on a Tuesday.6.3 Desorpt

46、ion cycleAfter 144 h of absorption, the test specimens are put on their side on a rack in the conditioning room (5.6.1). The spacing between the specimens is a minimum of 10 mm to ensure a good air circulation in the vicinity of the specimens.After 1 h, the test specimens are weighed. Record the ela

47、psed time (y) and mass to the nearest 0,01 g (my). Put the test specimen back on the rack.Repeat this after 4 h, 8 h, 24 h, 48 h, 72 h, 96 h and 168 h.All handling of the test specimens should be carried out in the conditioning room (5.6.1).NOTE Considering the recommended start point of the absorpt

48、ion cycle, the measurements for the desorption cycle are made at 96 h and 168 h to avoid data recording during the weekend.6.4 Additional short-term absorption cycleTo evaluate the moisture behaviour of the wood materials in the early phase of wetting a separate short-term absorption is performed.Th

49、e specimens should be conditioned in the climate chamber (5.6.1) for three weeks. The test specimens are put on their side on a rack. The spacing between the specimens is a minimum of 10 mm to ensure a good air circulation in the vicinity of the specimens.Weigh the test specimens to the nearest 0,01g and record the initial mass (mi).Fill a container with demineralized water (5.5.1) and place in the conditioning room (5.6.1).Place the test specimens in the water ensuring that the sample is fully submerged and put a tra