1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 717-3 : 1996 The Eu
2、ropean Standard EN 717-3 : 1996 has the status of a British Standard ICS 79.060 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Wood-based panels Determination of formaldehyde release Part 3. Formaldehyde release by the flask methodThis British Standard, having been prepared u
3、nder the direction of the Sector Board for Building and Civil Engineering, was published under the authority of the Standards Board and comes into effect on 15 September 1996 BSI 1996 The following BSI references relate to the work on this standard: Committee reference B/541 Draft for comment 93/111
4、164 DC ISBN 0 580 25888 2 BS 717-3 : 1996 Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee B/541, Wood based panels, upon which the following bodies were repr
5、esented: APA Engineered Wood Association Association of British Plywood and Veneer Manufacturers British Woodworking Federation Council of the Forest Industries of British Columbia Department of the Environment (Building Research Establishment) Finnish Plywood International Flat Roofing Contractors
6、Advisory Board Forestry Commission Furniture Industry Research Association Institution of Structural Engineers Local Authority Organizations Mineral Bonded Board Products Federation National Federation of Roofing Contractors National House-building Council National Panel Products Association Royal I
7、nstitute of British Architects Structural Board Association Timber Research and Development Association Timber Trade Federation Wood Panel Industries Federation Zurich Municipal Building GuaranteeBS EN 717-3 : 1996 BSI 1996 i Contents Page Committees responsible Inside front cover National foreword
8、ii Foreword 2 Text of EN 717-3 3ii BSI 1996 BS EN 717-3 : 1996 1) In preparation. National foreword This British Standard has been prepared by Technical Committee B/541 and is the English language version of EN 717-3 : 1996 Wood-based panels Determination of formaldehyde release Part 3: Formaldehyde
9、 release by the flask method, published by the European Committee for Standardization (CEN). EN 717-3 was published as a result of international discussion in which the UK took an active part. It is one of a series of standards specifying methods for determining formaldehyde potential in or formalde
10、hyde release from wood-based panels. The other standards of this series are: EN 120 Wood-based panels Determination of formaldehyde content Extraction method called the perforator method EN 717-1 Wood-based panels Determination of formaldehyde release Part 1: Formaldehyde release by the chamber meth
11、od 1) EN 717-2 Wood-based panels Determination of formaldehyde release Part 2: Formaldehyde release by the gas analysis method There is no equivalent test to EN 717-3 in the British Standard for particleboard (BS 5669) or in the British Standard for fibre building boards (BS 1142). Compliance with a
12、 British Standard does not of itself confer immunity from legal obligations.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN members Ref. No. EN 717-
13、3 : 1996 E EUROPEAN STANDARD EN 717-3 NORME EUROPE ENNE EUROPA ISCHE NORM March 1996 ICS 79.060.20 Descriptors: Wood products, wooden boards, determination, emission, formaldehyde, analysis methods English version Wood-based panels Determination of formaldehyde release Part 3: Formaldehyde release b
14、y the flask method Panneaux a base de bois De termination du de gagement de formalde hyde Partie 3: De gagement de formalde hyde par la me thode au bocal Holzwerkstoffe Bestimmung der Formaldehydabgabe Teil 3: Formaldehydabgabe nach der Flaschen-Methode This European Standard was approved by CEN on
15、1995-12-22. CEN members are bound to comply with the CEN/CENELEC 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 o
16、btained on application to the Central Secretariat 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 Central S
17、ecretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 717-3 : 1
18、996 BSI 1996 1) At present at the draft stage Foreword This European Standard has been prepared by Technical Committee CEN/TC 112, Wood-based panels, the Secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identica
19、l text or by endorsement, at the latest by September 1996, and conflicting national standards shall be withdrawn at the latest by September 1996. This standard is one of a series which specifies methods for determining formaldehyde potential in or formaldehyde release from wood-based panels. The oth
20、er standards in this series are: EN 120 Wood-based panels Determination of formaldehyde content Extraction method called the perforator method EN 717-1 Wood-based panels Determination of formaldehyde release Part 1: Formaldehyde release by the chamber method 1) EN 717-2 Wood-based panels Determinati
21、on of formaldehyde release Part 2: Formaldehyde release by the gas analysis method No existing European Standard is superseded. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, B
22、elgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Contents Page 1 Scope 3 2 Normative references 3 3 Principle 3 4 Reagents 3 5 Apparatus 3 6 Test pieces 4 7 Procedure 5 8 Expressi
23、on of results 7 9 Test report 7Page 3 EN 717-3 : 1996 BSI 1996 Introduction The principle of the flask method for measuring the formaldehyde release has been published by Wilhelm-Klauditz-Institute (Roffael 1975). Thereafter, the method has been modified in different ways by many authors in several
24、countries. After consideration of published work focusing on the method and its reliability, a temperature of 40 C and a period of 3 h have been selected for this standard. 1 Scope This European Standard specifies a method, known as the flask method, for determination of formaldehyde release from un
25、coated wood-based panels. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subseque
26、nt 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 referred to applies. EN 322 Wood-based panels Determination of moisture content EN 323 Wood-
27、based panels Determination of density EN 326-1 Wood-based panels Sampling, cutting and inspection Part 1: Sampling and cutting of test pieces and expression of test results 3 Principle Formaldehyde release is determined by suspending test pieces of known mass over water in a closed container, mainta
28、ined at a constant temperature. Formaldehyde released from the test pieces during a defined period of time is absorbed by the water. The formaldehyde content of the water is determined photometrically by the acetylacetone method, and the result is expressed in milligrams formaldehyde per kilogram of
29、 dry board. 4 Reagents 4.1 General Reagents of recognized analytical purity and distilled or demineralized water (referred to below as distilled water) shall be used for the analysis. 4.2 Acetylacetone, of analytical grade. 4.3 Ammonium acetate, of analytical grade. NOTE: Commercially prepared reage
30、nts may be used, provided it can be shown that they give an equivalent result. 5 Apparatus 5.1 Test apparatus Test apparatus consisting of the following main components: 5.1.1 Polypropylene, or polyethylene flask-container of type 1 or 2 (see figures 1 and 2), of 500 ml volume with tightly fitting l
31、id of the same material. 5.1.2 Metal test piece holder or rubber band and hook. Metal parts shall be of stainless steel (see figures 1 and 2). 5.2 Laboratory equipment 5.2.1 Waterbath, capable of maintaining a temperature of (40 1) C. 5.2.2 Cells, with a suitable path length for the spectrophotomete
32、r. 5.2.3 Volumetric flasks 1000 ml (calibrated at 20 C). 5.2.4 Volumetric flasks 100 ml (calibrated at 20 C). 5.2.5 Flasks 50 ml (with stoppers). 5.2.6 Bulb pipettes (calibrated at 20 C), 5 ml, 10 ml, 15 ml, 20 ml, 25 ml, 50 ml, 100 ml. 5.2.7 Erlenmeyer flask 250 ml. 5.2.8 Microburette. 5.2.9 Burett
33、e 50 ml, graduated in 0,05 ml (calibrated at 20 C). 5.2.10 Stop watch. 5.2.11 Balance, scale interval 0,001 g. 5.2.12 Ventilated drying oven, capable of maintaining a temperature of (103 2) C. 5.2.13 Ventilated oven (maximum volume: 60 l), capable of maintaining a temperature of (40 1) C at any posi
34、tion in the oven. 5.2.14 Spectrophotometer, capable of measuring absorbance at 412 nm.Page 4 EN 717-3 : 1996 BSI 1996 1 2 3 4 5 Lid 500 ml container Sealing joints Hook with thread diameter of 3 mm to 4 mm Surface of water Dimensions in millimetres NOTE. The dimensions of the clip and of the hook ar
35、e only examples Figure 1. Test apparatus type 1 for the flask method 1 2 3 4 500 ml polyethylene bottle with bottle top Hook out of stainless steel Elastic rubber band Surface of water Dimensions in millimetres Figure 2. Test apparatus type 2 for the flask method 6 Test pieces 6.1 Sampling Test piec
36、es of 25 mm3 25 mm3 board thickness shall be taken according to EN 326-1, evenly distributed over the width of the (cooled) board, but excluding a 500 mm wide strip at either end of the board. 6.2 Test pieces for the determination of the moisture content Take 12 test pieces for the determination of
37、the moisture content. 6.3 Test pieces for the determination of the flask value Take a sufficient number of test pieces to obtain approximately 100 g of board for determining the flask value (F v ). Determine the mass of the test pieces to the nearest 0,01 g. The number of test pieces for each set ha
38、s to be chosen so that their total mass is as near as possible to 20 g. In case of doubt the total mass should be preferably below 20 g. The test pieces shall be cut immediately after the board has been cooled. After cutting, the test pieces shall be stored, hermetically sealed, at room temperature.
39、 For comparative reasons the time elapsing between cutting and testing should be kept as constant as possible, but shall not exceed 72 h.Page 5 EN 717-3 : 1996 BSI 1996 7 Procedure 7.1 Determination of moisture content Determine the moisture content in accordance with EN 322. Determine the moisture
40、content in duplicate on two samples of at least four test pieces. 7.2 Determination of formaldehyde release Determinations shall always be made on duplicate sets of test pieces. The individual values shall only differ from each other by a maximum of 20 % related to the higher of two single values. O
41、therwise a third determination shall be carried out. Fix the test pieces face to face in the clip and attach the clip to the lid of the container, using the hook as shown in figure 1 or fix the test pieces with a rubber band as shown in figure 2. Add 50 ml of distilled water at 20 C to the container
42、 using a bulb pipette, attach the lid with the suspended test pieces and close the container so that it is completely airtight. The bottom surfaces of the test pieces should be approximately 40 mm above the surface of the water. A second container shall be prepared in the same way. Insert the closed
43、 containers into the oven (see 5.2.13) at a temperature of (40 1) C. This temperature shall be maintained throughout the whole test period. The containers shall occupy less than 10 % of the whole volume of the oven, that means not more than one container per 6 l of oven volume in order to avoid fluc
44、tuation in the temperature. The containers shall be placed staggered and with a distance of at least 50 mm between each other. After (180 1) min remove the containers from the oven and immediately take off the lids with the test pieces attached. Transfer the solution from the containers to each of t
45、he two 50 ml flasks, close them tightly and allow the contents to cool at ambient temperature to approximately 20 C. 7.3 Determination of formaldehyde concentration of the aqueous solution 7.3.1 General The formaldehyde content of the aqueous solution shall be determined photometrically. 7.3.2 Princ
46、iple The determination is based on the Hantzsch reaction in which aqueous formaldehyde reacts with ammonium ions and acetylacetone to yield diacetyldhydrolutidline (DDL). DDL has an absorption maximum at 412 nm. The reaction is specific to formaldehyde. NOTE: Other suitable photometric procedures ma
47、y also be used. 7.3.3 Reagents 7.3.3.1 Acetylacetone solution 4 ml acetylacetone are added to a 1000 ml volumetric flask and made up to the mark with distilled water. 7.3.3.2 Ammonium acetate solution 200 g ammonium acetate are dissolved with distilled water in a 1000 ml volumetric flask and made up
48、 to the mark. 7.3.4 Procedure 10 ml are taken from the aqueous solution (see 7.2) with a pipette (5.2.6) and added to 10 ml acetylacetone solution (7.3.3.1) and 10 ml ammonium acetate solution (7.3.3.2) in a 50 ml flask (5.2.5). The flask is stoppered, shaken and warmed for 15 min in a water bath (5
49、.2.1) of (40 1) C. The now greenish-yellow solution is cooled to room temperature protected from light (about 1 h). The absorbance of this solution is determined at a wavelength of 412 nm against distilled water using a spectrophotometer (5.2.14). A blank test shall be made with distilled water, the blank value shall be taken into consideration in the determinations of the flask value (F v ). 7.3.5 Calibration curve (see figure 3) 7.3.5.1 General A calibration curve is produced fr
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