EN 717-3-1996人造板甲醛释放测试（可编辑）

EN 717-3-1996人造板甲醛释放测试（可编辑） EN 717-3-1996人造板甲醛释放测试 EN 717-3 EUROPEAN STANDARDNORME EUROPEENNE ? March 1996 EUROPAISCHE NORM 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 by the flask method Panneaux a ` base de bois ? De ?termination du Holzwerkstoffe ? Bestimmung der de ?gagement de formalde ?hyde ? Formaldehydabgabe ? Partie 3: De ?gagement de formalde ?hyde par la Teil 3: Formaldehydabgabe nach der me ?thode au bocal Flaschen-Methode This European Standard was approved by CEN on 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 obtained 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 Secretariat 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. CEN European Committee for Standardization ComiteEurope ?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 717-3 : 1996 EPage 2 EN 717-3 : 1996 Foreword Contents This European Standard has been prepared by Technical Committee CEN/TC 112, Wood-based panels, Page the Secretariat of which is held by DIN. 1 Scope 3 This European Standard shall be given the status of a national standard, either by publication of an identical 2 Normative references 3 text or by endorsement, at the latest by 3 Principle 3 September 1996, and conflicting national standards 4 Reagents 3 shall be withdrawn at the latest by September 1996. 5 Apparatus 3 This standard is one of a series which specifies methods for determining formaldehyde potential in or 6 Test pieces 4 formaldehyde release from wood-based panels. 7 Procedure 5 The other standards in this series are: 8 Expression of results 7 EN 120 Wood-based panels ? Determination of 9 Test report 7 formaldehyde content ? Extraction method called the perforator method EN 717-1 Wood-based panels ? Determination of formaldehyde release ? Part 1: Formaldehyde release by the 1 chamber method EN 717-2 Wood-based panels ? Determination 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, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. 1 At present at the draft stage BSI 1996Page 3 EN 717-3 : 1996 Introduction 4 Reagents The principle of the flask method for measuring the 4.1 General formaldehyde release has been published by Reagents of recognized analytical purity and distilled Wilhelm-Klauditz-Institute Roffael 1975. Thereafter, or demineralized water referred to below as distilled the method has been modified in different ways by water shall be used for the analysis. many authors in several countries. After consideration of published work focusing on the method and its 4.2 Acetylacetone, of analytical grade. reliability, a temperature of 40 ?C and a period of 3 h 4.3 Ammonium acetate, of analytical grade. have been selected for this standard. NOTE: Commercially prepared reagents may be used, provided it can be shown that they give an equivalent result. 1 Scope This European Standard specifies a method, known as 5 Apparatus the flask method, for determination of formaldehyde release from uncoated wood-based panels. 5.1 Test apparatus Test apparatus consisting of the following main components: 2 Normative references 5.1.1 Polypropylene, or polyethylene flask-container of This European Standard incorporates by dated or type 1 or 2 see figures 1 and 2, of 500 ml volume undated reference, provisions from other publications. with tightly fitting lid of the same material. These normative references are cited at the appropriate places in the text and the publications are 5.1.2 Metal test piece holder or rubber band and hook. listed hereafter. For dated references, subsequent Metal parts shall be of stainless steel see figures 1 amendments to or revisions of any of these and 2. publications apply to this European Standard, only when incorporated in it by amendment or revision. For 5.2 Laboratory equipment undated references the latest edition of the publication 5.2.1 Waterbath, capable of maintaining a temperature referred to applies. ? of 40 1 ?C. EN 322 Wood-based panels ? Determination of 5.2.2 Cells, with a suitable path length for the moisture content spectrophotometer. EN 323 Wood-based panels ? Determination of 5.2.3 Volumetric flasks 1000 ml calibrated at 20 ?C. density 5.2.4 Volumetric flasks 100 ml calibrated at 20 ?C. EN 326-1 Wood-based panels ? Sampling, cutting and inspection ? Part 1: Sampling and 5.2.5 Flasks 50 ml with stoppers. cutting of test pieces and expression of test 5.2.6 Bulb pipettes calibrated at 20 ?C, 5 ml, 10 ml, results 15 ml, 20 ml, 25 ml, 50 ml, 100 ml. 5.2.7 Erlenmeyer flask 250 ml. 3 Principle 5.2.8 Microburette. Formaldehyde release is determined by suspending test pieces of known mass over water in a closed 5.2.9 Burette 50 ml, graduated in 0,05 ml calibrated container, maintained at a constant temperature. at 20 ?C. Formaldehyde released from the test pieces during a 5.2.10 Stop watch. defined period of time is absorbed by the water. The formaldehyde content of the water is determined 5.2.11 Balance, scale interval 0,001 g. photometrically by the acetylacetone method, and the 5.2.12 Ventilated drying oven, capable of maintaining result is expressed in milligrams formaldehyde per ? a temperature of 103 2 ?C. kilogram of dry board. 5.2.13 Ventilated oven imum volume: 60 l, ? capable of maintaining a temperature of 40 1 ?C at any position in the oven. 5.2.14 Spectrophotometer, capable of measuring absorbance at 412 nm. BSI 1996Page 4 EN 717-3 : 1996 1 Lid 2 500 ml container 3 Sealing joints 4 Hook with thread diameter of 3 mm to 4 mm 5 Surface of water Dimensions in millimetres NOTE. The dimensions of the clip and of the hook are only examples Figure 1. Test apparatus type 1 for the flask method 6 Test pieces 6.1 Sampling Test pieces 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 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 . Determine the mass of the test pieces to the v nearest 0,01 g. The number of test pieces for each set has 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 1 500 ml polyethylene bottle with bottle top board has been cooled. After cutting, the test pieces 2 Hook out of stainless steel shall be stored, hermetically sealed, at room 3 Elastic rubber band temperature. For comparative reasons the time 4 Surface of water elapsing between cutting and testing should be kept as Dimensions in millimetres constant as possible, but shall not exceed 72 h. Figure 2. Test apparatus type 2 for the flask method BSI 1996Page 5 EN 717-3 : 1996 7.3.3 Reagents 7 Procedure 7.3.3.1 Acetylacetone solution 7.1 Determination of moisture content 4 ml acetylacetone are added to a 1000 ml volumetric Determine the moisture content in accordance flask and made up to the mark with distilled water. with EN 322. Determine the moisture content in duplicate on two 7.3.3.2 Ammonium acetate solution samples of at least four test pieces. 200 g ammonium acetate are dissolved with distilled water in a 1000 ml volumetric flask and made up to the 7.2 Determination of formaldehyde release mark. Determinations shall always be made on duplicate sets of test pieces. The individual values shall only differ 7.3.4 Procedure from each other by a imum of 20 % related to the 10 ml are taken from the aqueous solution see 7.2 higher of two single values. Otherwise a third with a pipette 5.2.6 and added to 10 ml acetylacetone determination shall be carried out. solution 7.3.3.1 and 10 ml ammonium acetate Fix the test pieces face to face in the clip and attach solution 7.3.3.2 in a 50 ml flask 5.2.5. The flask is the clip to the lid of the container, using the hook as stoppered, shaken and warmed for 15 min in a water ? shown in figure 1 or fix the test pieces with a rubber bath 5.2.1 of 40 1 ?C. The now greenish-yellow band as shown in figure 2. Add 50 ml of distilled water solution is cooled to room temperature protected from at 20 ?C to the container using a bulb pipette, attach light about 1 h. The absorbance of this solution is the lid with the suspended test pieces and close the determined at a wavelength of 412 nm against distilled container so that it is completely airtight. The bottom water using a spectrophotometer 5.2.14. A blank test surfaces of the test pieces should be approximately shall be made with distilled water, the blank value shall 40 mm above the surface of the water. A second be taken into consideration in the determinations of container shall be prepared in the same way. the flask value F . v Insert the closed containers into the oven see 5.2.13 7.3.5 Calibration curve see figure 3 ? at a temperature of 40 1 ?C. This temperature shall 7.3.5.1 General be maintained throughout the whole test period. The containers shall occupy less than 10 % of the whole A calibration curve is produced from a standard volume of the oven, that means not more than one formaldehyde solution, the concentration of which has container per 6 l of oven volume in order to avoid been determined by iodometric titration. The fluctuation in the temperature. The containers shall be calibration curve shall be checked at least once a placed staggered and with a distance of at least 50 mm week. ? between each other. After 180 1 min remove the 7.3.5.2 Formaldehyde standard solution containers from the oven and immediately take off the Reagents: lids with the test pieces attached. Transfer the solution from the containers to each of the two 50 ml flasks, ? standard iodine solution c I 0,05 mol/l; 2 close them tightly and allow the contents to cool at ? standard sodium thiosulfate solution ambient temperature to approximately 20 ?C. c Na S O 0,1 mol/l; 2 2 3 7.3 Determination of formaldehyde ? standard sodium hydroxide solution concentration of the aqueous solution c NaOH 1 mol/l; ? standard sulfuric acid solution 7.3.1 General c H SO 1 mol/l. 2 4 The formaldehyde content of the aqueous solution The above solutions shall be standardized before use. shall be determined photometrically. ? starch solution 1 % m/m. 7.3.2 Principle Dilute about 2,5 g formaldehyde solution The determination is based on the Hantzsch reaction in concentration 35 % to 40 % in a 1000 ml volumetric which aqueous formaldehyde reacts with ammonium flask with distilled water and make up to the mark. ions and acetylacetone to yield diacetyldhydrolutidline Determine the exact formaldehyde concentration as DDL. DDL has an absorption imum at 412 nm. follows: The reaction is specific to formaldehyde. mix 20 ml of the formaldehyde standard solution NOTE: Other suitable photometric procedures may also be used. with 25 ml iodine solution and 10 ml sodium hydroxide solution. After 15 min standing protected from light add 15 ml of sulfuric acid solution. Titrate back the excess iodine with the sodium thiosulfate solution. Near the end of the titration add some drops of the starch solution as an indicator. Carry out in parallel a blank test with 20 ml of distilled water. BSI 1996Page 6 EN 717-3 : 1996 Calculate the formaldehyde content as follows: 7.3.5.3 Formaldehyde calibration solution c HCHO V 2 V3 153 cNa S O 3 Using the concentration determined in 7.3.5.2, o 2 2 3 calculate the volume of the formaldehyde solution 3 1000/20 1 which will contain 15 mg formaldehyde. Transfer this where: volume, using a microburette 5.2.8, to a 1000 ml c HCHO is the formaldehyde concentration, in volumetric flask 5.2.3 and make up to the mark with milligrams per litre; distilled water. 1 ml of this calibration solution contains 15mg formaldehyde. V is the volume of the thiosulfate titration solution, in millilitres; 7.3.5.4 Determination of the calibration curve V is the volume of thiosulfate titration for the blank, o Pipette either zero, 5, 10, 20, 50 or 100 ml of in millilitres; formaldehyde calibration solution see 7.3.5.3 into c Na S O is the concentration of sodium 2 2 3 a 100 ml volumetric flask 5.2.4 and make up to the thiosulfate solution, in moles per litre. mark with distilled water. 10 ml of each dilution is NOTE: 1 ml 0,1 mol/l thiosulfate solution corresponds to analysed photometrically by the same procedure as 1 ml 0,05 mol/l iodine solution and 1,5 mg formaldehyde. described in 7.3.4. The absorbance values are plotted against the formaldehyde concentrations c between 0 mg/ml and 0,015 mg/ml. The slope fof the graph is determined either graphically, or calculated see figure 3. c f3 A 2 A s B a Concentration of the diluted calibration solution c b Absorbance A 2 A S B Figure 3. Example of a calibration curve for formaldehyde determined by acetylacetone method path length 10 mm BSI 1996Page 7 EN 717-3 : 1996 8 Expression of results 9 Test report The test report shall be issued in accordance with 8.1 Moisture content EN 326-1. Additionally, the test report shall include the The moisture content H shall be calculated according following information: to EN 322. ? type of board; 8.2 Flask value F v ? density of the board according to EN 323, in The amount of formaldehyde absorbed in 10 ml of kilograms per cubic metre; solution from the containers is determined ? information regarding age, finishing, sanding etc.; spectrophotometrically as described under 7.3.4. ? date of formaldehyde determination; The flask value F in milligrams per kilogram of v ? moisture content, in percent, at the time of testing; oven-dry board is calculated by the following equation: ? flask value F in milligrams per kilogram v A 2 A 3 f3 503 10 100 + H s B F 2 expressed to 0,1 mg/kg oven-dry board individual v m values of each determination and mean value; where: ? description of further details. A is the absorbance of the analysed solution from S the containers; A is the absorbance of an analysis with distilled B water; f is the slope of the calibration curve, in milligrams per millilitre; H is the moisture content of the test pieces, in percent; m is the mass of the test pieces, in grams. BSI 19968 blank