1、CEN EN*L20 92 3404589 003LOb9 362 = EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 120:1992 July 1992 UDC 674.81 5: 620.1 : 543.242.3: 547.281 1 Supersedes EN 120:1984 Descriptors: Wooden boards, particle bbards, fibre boards, plywood, chemical analysis, determination of content, gxtraction me
2、thods, perforators English version Wood based panels - Determination of formaldehyde content - Extraction. method called the perforator method Panneaux base de bois - Dtermination de la teneur en formaldhyde - Mthode dextraction dite dthcde au perforateur Holzwerkstoffe - Bestimmung des Formaldehydg
3、ehalts - Extrationsverfahren genannt Perforatorrnethode This European Standard was approved by CEN on 1992-07-01. 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 a
4、lteration. 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 Standards exist in three official versions (English, French, German). A version in any other language made by tra
5、nslation 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, Finiad, France, Germany, Greece, Iceland, Ireland, Italy, Luxembou
6、rg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdm. CEN European Cornnittee for Standardization Comit Europen de Normalisation Europisches Kanitee fr Nomng Central Secretariat: rue de Slassart,3 8-1050 Emssels o 1992 Copyright reserved to CEN members Ref. No. EN 120:1992
7、 E Page 2 EN 120:1992 - CEN ENJL20 92 = 3404589 003L070 U84 M Contents list Page scope . Normative references Principle . Reagents Apparatus :. . Test pieces . Procedure . Expression of results . Test report . 4 4 4 4- 4 5 6 9 9 - I CEN EN*lIZCI 92 3404589 003L07 T10 = This European (Secretariat : (
8、Secretariat : Page 3 EN 120:1992 Foreword -. - 4 Standard was prepared by Working Group 5 “Formaldehyde“ . Germany) of Technical Committee CEN/TC 112 “Wood-based panels“ Germany). This European Standard is based on the October 1984 edition. To that times the work was the responsibility of CEN/TC 91
9、Particleboards - Formaldehyde“ and it was only intented for determining the formaldehyde content of particleboards. The basis was an extraction method developed by the European Federation of Associations of Particleboard Manufacturers, FESYP, and known as the “Perforator Method“. This method was int
10、ented for testing particularly particleboards at the manufacturing stage, and was later adapted for testing all wood-based panels. For this European standard a mandate “Timber Structures“ has been given to CEN and EFTA in the framework of the Directive on the approximation of laws, regulations and a
11、dministrative provisions of the Member States relating to construction products (89/106/EEC). National Standards identicalto this European Standard shall be published at the latest by 93-01-31 and conflicting national standards shall be withdrawn at the lbtest by 93-01-31. In accordance with the Com
12、mon CEN/CENELEC Rules 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. Introduction The “perforat
13、or value“ as determined by the method laid down in this standard is considered to be the “formaldehyde content“ of the tested board. The test results shall be considered in relation to the specific board conditions at the time of testing. The emission of formaldehyde from wood-based panels (e.g. par
14、ticleboard, plywood, fibreboard) is a complex process. For a given board, the test result depends upon the age, ageing conditions, moisture content etc., at the time of testing. In addition, the correlation between the perforator value and the formaldehyde emission of the board depends on the type o
15、f board. CEN EN*l120 92 0 3404589 0033072 957 Page 4 EN 120:1992 1 Scope This European Standard specifies an extraction method, known as the “Perforator Method“. It is used for the determination of the formaldehyde content of unlaminated and uncoated wood-based panels. 2 Normative references This Eu
16、ropean Standard incorporates by dated or undated reference, provision from-other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated reference, subsequent amendments to or revisions of any Of these publications
17、 apply to this European Standard only when incorPoratGd .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 3 Principle The formaldehyde is extracted from test pieces by means
18、of boiling toluene and then transferred into distilled or demineralized water. The formaldehyde content of this aqueous solution is determined photo- metrically by the acetylacetone method. 4 Reagents For the analysis, only reagents of analytical quality and distilled or demineralized water shall be
19、 used. 4.1 Toluene, which is free from water and from impurities which may interfere with the test. 4.2 Acetylacetone of analytical grade 4.3 Ammonium acetate of analytical grade NOTE: valent result. Commercially prepared solutions may be used, provided it can be shown that they give an equi- .5 App
20、aratus 5.1 Precision balance, scale interval 0,001 g. 5.2 Well ventilated drying oven, capable of maintaining a temperature of (103 f 2) *C 5.3 Spectrophotometer 5.4 Extraction apparatus The apparatus consists of: - Spiral Condenser, total length approximately 400 mm, cone 45/40, socket 29/32 (item
21、reference 2) - Conical adaptor, socket 45/40, cone 71/51 (item reference 3) - Filter insert, porosity P 160 (100 pm to 160 vm), bowl and filter diameter 60 mm - Perforator attachment 1000 ml with stopcock (4 mm bore), socket 71/51, cone 29/32 - Conical adaptor, socket 29/32, cone 45/40 (item referen
22、ce 8) - 1000 ml round-bottomed flask, socket 45/40 (item reference 9) i tem reference (item reference CEN EN*lt20 72 E 3404589 0031373 893 E Page 5 EN 120:1992 - (Double) bulbed tube, cone 29/32 (length approximately 380 mm), external diameter approximately 10 mm, bulb diameter approximately 50 mm,
23、distance between bulb and bottom end of tube approximately 200 mm (distance between the bulbs approximately 50 mm) (item reference 6) - Absorption bulb (e. g. conical flask 250 mi) (item reference 7). NOTE: The-item references are given in figure 1. 5.5 Laboratory equipment . - Volumetric flask 2000
24、 ml, calibi.ated:_at. 20 *C - Conical flask, 250 ml - Precision burette, 50 ml, calibrated at 20 *C - Watch glass with diameter of about 120 mm - Two volumetric flasks, 1000 ml, calibrated at 20 C - Six volumetric flasks, 700 ml, calibrated at 20 *C - Bulb pipette, 100 ml, calibrated at 20 *C - Bulb
25、 pipette, 25 ml, calibrated at 20 *C - Three bulb pipettes, 10 ml, calibrated at-20 *C - Stoppered flasks each 50 ml - Two volumetric cylinders, 250 a11 - Water bath - Desiccator 6 Test piece5 6.1 Sampling 6.1.1 The test pieces are to be taken, evenly distributed, over the width of the (cooled) boar
26、d but exclu- ding a 500 mm wide strip at either end of the board. 6.1.2 Take 12 test pieces of 25 mm x 25 mm x thickness of the board for the determination of the moisture. content and a sufficient number of test pieces of the same dimensions to obtain approximately 500 g of the board for the extrac
27、tion by perforator. *. 6.2 For production control If this method is used for production control, the board selected for sampling is immediately cut up after cooling. The test pieces taken from the board are to be stored hermetically sealed at room temperature. The formaldehyde determination should b
28、e carried out not more than 72 hours after sampling. CEN ENwL20 92 I 3404589 0031074 2T Page 6 EN 120:1992 6.3 For other purposes If this method is used for other purposes, e. 9. for boards already installed, the method chosen for samp- ling, preparation of test pieces and conditioning, all which in
29、fluence the final result, shall be agreed between the parties and indicated in the test report. Unless otherwise agreed, the test pieces shall be conditioned to a constant mass at a temperature of (23 f 1) *C and a relative humidity of (45 i 5) %. Constant mass is considered to have been reached whe
30、n the results of two successive weighings, carried Out at intervals of not less than 24 hours, do not differ by more than 0,l % of the mass of the test pieces. Contamination of test pieces from Othe; SOurCeS of formaldehyde during the conditioning shall be avoided. , NOTE: Action Committee “Indoor a
31、ir quality and its impact on man“ (COST 613) of the European Community given in the report “Formaldehyde emission from wood-based materials: Guideline for the determination of steady state concentrations in test chambers“. The climate for conditioning Of test pieces is the test climate recommended b
32、y the Concerted 7 Procedure 7.1 Number of extractions The extractions are to be carried out in duplicate. NOTE: For internal routine control, a single extraction may be sufficient. The individual values of a duplicate extraction may not deviate by more than 20 % related to the greater of the two sin
33、gle values; otherwise a third extraction is to be carried out. 7.2 Determination of moisture content Determine the moisture content in accordance with EN 322. Determine the moisture content in duplicate on a sample of at least 4 test pieces (25 mm x 25 min). Weigh the sample (5.1) to an accuracy of
34、0,l t onto the watch glass (5.5) and dry in the oven (5.2) at a temperature of (103 t 2) *C to constant mass (about 12 h). Constant mass is considered to have been reached when the results of two successive weighings, carried out at intervals of not less than 6 hours, do not differ by more than 0,l
35、% of the mass of the test pieces. , After the removal from the drying oven, the test pieces shall be allowed to cool in a desiccator before weighing. 7.3 Extraction in the perforator NOTE: thermal insulation, in order to achieve circulation of the toluene. Before the apparatus is used the sidearm of
36、 the perforator attachment shall be provided with About 110 g of test pieces arc weighed to an accuracy of 0,l g and put into the round bottom flask (5.4). 600 ml of toluene (4.1) are added. Subsequently, the round bottom flask is connected to the perforator. About 1000 ml of distilled water is pour
37、ed into the perforator attachment, leaving a space of 20 mm to 30 mm between the surface of the water and the siphon outlet. The condenser and the gas absorption equipment are then connected. lhe absorption bulb of the gas absorption equipment (5.4) is filled with about 100 ml of distilled water and
38、 connected to t.he apparatus. When the apparatus has been assembled, the cooling water and heating are turned-on. Toluene shall flow back regularly throughout the whole period of perforation, with a reflux rate of 70 drops to 90 drops per minute. Care shall be taken that no water flows back from the
39、 absorption bulb (item reference 7) into other parts of the equipment during and after the extraction process. CEN EN*320 92 W 3484589 0033075 bbb W Page 7 EN 120:1992 The extraction is carried on for two hours, starting at the moment that the first bubbles pass through the filter insert. The heatin
40、g shall be such that the onset Of bubbling occurs between 20 minutes and 30 minutes after turning on the heating device. After these two hours the heating is switched off and the gas absorption bulb is removed. The water contained in the perforator is, after cooling to room temperature, transferred
41、into the volumetric flask by means of the stop cock. The perforator is rinsed twice. each time with 200 ml of distilled water. The rinsing water is poured into the volumetric flask and the toluene discarded. The water contained in the absorption bulb of the gas absorption equipment is poured into th
42、e flask. The voJume of the water contained in the flask is then made up to 2000 ml with distilled water. 7.4 Slank test Repeat the test without test pieces using new toluene from the same batch as used for the extraction. NOTE: than 1 mg/600 ml of toluene the toluene shall be rejected. The quality o
43、f toluene is checked by this test, If the -blank value of formaldehyde is higher 7.5 Determination of formaldehyde in the extract The formaldehyde content of the aqueous extract is determined photometrically, using the acetylacetone met hod. 7.5.1 Principle The determination is based on the Handtzsc
44、h reaction in which aqueous formaldehyde reacts with ammonium ions and acetylacetone to yield diacetyldihydrolutidine (OOL). ODL has an absorbance maximum at 412 nm. The reaction is highly specific to formaldehyde. NOTE: Other suitable photometric procedures may also be used. 7.5.2 Reagents 7.5.2.1
45、Acetylacetone solution 4 ml acetylabetone is added to a 1000 ml volumetric flask, dissolved in distilled water and made up to the mark with distilled water. 7.5.2.2 Ammonium acetate solution 200 g ammonium acetate is dissolved in distilled water in a 1000 in1 volumetric flask and nade up to the mark
46、. 7.5.3 Procedure 10 ml is taken from the aqueous solution (7.3) with a pipette and added to 10 nl acetylacetone solution (7.5.2.1) and 10 ml ammonium acetate solution (7.5.2.2) in a 50 m1 flask. The flask is stoppered, shaken and warmed for 15 minutes in a water bath of 40 *C. The now greenish-yell
47、ow solution is cooled to room temperature protected against the influence of light (about 1 hour). The absorbance of this solution is determined at a wavelength of 412 nm against distilled water using a spectrophotometer (5.3). A blank value is determined parallel with destilled water and taken into
48、 consideration in the determination of the perforator value (8.2). I CEN EN*J20 92 W 340i6589 0031076 5T2 W Page 0 EN 120:1992 7.5.4 Calibration curve The calibration curve (see figure 4) is produced from a standard- formaldehyde solution, the concentration of which has been determined by iodometric
49、 titration. The calibration curve shall be checked at least once a week. 7.5.4.1 Formaldehyde standard solution Reagents : - Standard iodine solution , . C(I2) 0,05 mol/l - Standard sodium thiosulphate solution c(Na2S203) I 0,l moi/l -. .- - Standard sodium hydroxide solution c(Na0H) = 1 mol/l - Standard sulphuric acid solution c(H2S04) = 1 mol/l - starch solution = 1 f m/m The solutions shall be standardized before use. About 2,5 g formaldehyde solution (concentration 35 % to AO %) are diluted in a 1000 nl volumetric flask with distilled water and made up to the ma
