ISO 15234 pdf download.Paints and varnishes — Testing of formaldehyde-emitting coatings and melamine foams — Determination of the steady-state concentration of formaldehyde in a small test chamber
1 Scope
This International Standard specifies a test method for determining the equilibrium concentration of formaldehyde from formaldehyde-emitting coatings and melamine foams in a small test chamber. It describes the determination of the equilibrium concentration of formaldehyde that is established in air at 23 °C and 50 % relative humidity. The test closely simulates practical conditions and can be performed on a laboratory scale. Good correlation is obtained with values obtained on samples of the same material in a 40 m 3 test chamber. The method, which is simple to perform, is therefore suitable for the preliminary determination of limits that have to be adhered to.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 3270:1 984, Paints and varnishes and their raw materials — Temperatures and humidities for conditioning and testing . ISO 3696:1 987, Water for analytical laboratory use — Specification and test method.
3 Definitions
For the purposes of this International Standard, the following definitions apply. 3.1 equilibrium concentration c eql the concentration of formaldehyde in the air in the test chamber that is reached when several successive values of the concentration determined at one-hour intervals differ by less than 0,02 mg/m 3
4 Principle
Test specimens are conditioned at (23 ± 1 ) °C and (50 ± 3) % relative humidity and exposed under specified conditions in a small test chamber (desiccator). The desiccator is set up in an air-conditioned room so that air from the room can be passed first through the desiccator and then into a water trap where formaldehyde (HCHO) is absorbed. The water in the water trap is changed at regular intervals, and the formaldehyde concentration c is determined photometrically by the acetylacetone method or another suitable method. The test is continued until the value measured for c no longer changes (see 3.1 ). The equilibrium concentration c eql in the air in the test chamber is then considered to be attained.
5 Choice of method for determination of formaldehyde
The acetylacetone method has been chosen as the preferred method. Other methods of determination, e.g. a fluorimetric method, may be used instead of the photometric method with acetylacetone, provided they can be shown to give equivalent results. (See also annex C, clause C.7.)
7 Reagents
During the analysis, use only reagents of recognized analytical grade and only water of at least grade 3 purity as defined in ISO 3696. 7.1 Colour-developer solution. Weigh 75,0 g of ammonium acetate into a 500 ml volumetric flask and dissolve in water. Add 1 ,5 ml of concentrated acetic acid (96 % minimum) and 1 ,0 ml of acetylacetone. Make up to the mark with water and mix well. The solution is not stable. It may not be kept for more than 1 4 days at room temperature (temperature no higher than 28 °C). 7.2 Formaldehyde, standard stock solution containing about 1 g/l of formaldehyde. Weigh about 3 g of 30 % formaldehyde solution into a 1 00 ml beaker and dilute with water. Transfer the diluted solution into a 1 000 ml volumetric flask, make up to the mark with water and mix well. Determine the formaldehyde content of this solution as follows: To 20 ml of the formaldehyde stock solution add 25 ml of iodine solution [c(I 2 ) = 0,05 mol/l, corresponding to 1 2,69 g/l of I 2 ] and 1 0 ml of sodium hydroxide solution [c(NaOH) = 1 mol/l, corresponding to 40,00 g/l of NaOH].