BS 84 pdf free download
BS 84-2020 pdf free download.Durability of wood and wood-based products — Accelerated ageing of treated wood prior to biological testing — Leaching procedure.
6 Test specimens
6.1 Definition and origin The test specimens and their preparation are defined in the standards concerning the biological tests to which they are intended to be subjected. The leaching procedure shall be carried out after the end of the preparation of test specimens for testing described in the relevant biological test standard. This includes any treatment and subsequent conditioning period where relevant.
6.2 Number of test specimens The number of test specimens shall allow the relevant biological tests to be carried out in accordance with the instructions in the appropriate standards, bearing in mind that in some tests the leaching procedure shall be applied to control specimens as well as to test specimens. The control specimens may be of the following kinds where required by the relevant test standard: — check test specimens that will not be subjected to attack by biological agents after the leaching procedure. These will serve as controls for changes in mass in those tests in which this factor is taken into consideration; — untreated control or reference species specimens which, after leaching, are subjected to the test by biological agents to check any variation in the behaviour of the reference species.
7 Procedure
7.1 Leaching
7.1.1 Impregnation with water Place the test specimens in the test vessels (see 5.2.2). Do not place in the same vessel test specimens of different species, specimens treated with different products or with different concentrations or loadings of the same product, specimens from wood modified using different processes or to different extents, or both test and control specimens . Ballast them with weights (see 5.2.5) to prevent them from floating. Pour sufficient water (see 5.1) into the test vessels to cover the groups of test specimens and to ensure that the test specimens remain covered throughout the impregnation. Place the test vessels in the vacuum desiccator (see 5.2.3); establish a vacuum corresponding to a pressure of 4 kPa and maintain this for a minimum of 20 min before release. Leave the test specimens in the vessels for minimum 2 h. Empty the water from the vessels.
7.1.2 Immersion in water Refill each vessel with fresh water (see 5.1) to a ratio of approximately five volumes of water to one volume of wood (e.g. 100 ml of water per test specimen of 50 mm × 25 mm × 15 mm). NOTE It is not necessary to continue to ballast the test specimens as they will not float after the impregnation procedure. This cannot apply if e.g. wood-based panel product test specimens are being processed. Allow the test specimens to remain immersed in water for 14 days at the temperature specified (see 5.2.1) with nine changes of the water as follows: — change the water at the end of the first and second day of immersion; — change the water a further seven times in the remaining 12 days at intervals of not less than one day and not more than three days. 7.2 Drying Stand the test specimens in the conditioning (see 5.2.1), on one of their narrow sides on a non-absorbent support of material which does not react with the treated specimens and taking care to leave a gap of at latest 10 mm between individual test specimens, allowing a free flow of air around the test specimens. Allow the test specimens to stand for at least two weeks or until constant mass, i.e. until two consecutive weighings 24 h apart are the same ± 0,1 g.
8 Destination of the test specimens after the leaching procedure The test specimens are suitable for use in biological tests in accordance with the appropriate standards, commencing from the clause describing the procedure for exposing the test specimens to the test organisms (insects or fungi). For practical reasons it may not be possible to conduct the biological test immediately after the completion of the leaching procedure. The test blocks can be subjected to the start of the biological test up to a maximum of 12 months following the completion of the leaching procedure.
9 Reference to this document in biological test reports Quote the leaching procedure by giving the following information in the biological test reports: a) quote the leaching procedure by giving the number of this document (i.e. EN 84:2020); b) state the period of time between the completion of the leaching procedure and the start of the biological test; c) the temperature and relative humidity conditions in which the test blocks were kept prior to the start of the biological test; d) any deviation from the method described in this document.BS 84 pdf download.
