BS EN 117-2012 pdf download.Wood preservatives Determination of toxic values against Reticulitermes species (European termites) (Laboratory method).
8.1.2.1 Preparation of treatment solutions
8.1.2.1.1 Solid preservatives
Water-soluble preservatives: dissolve the preservative in water (5.2.3) to the required concentration.
Non-water-soluble preservatives: dissolve the preservative in an appropriate solvent (5.2.4) to the required
concentration.
8.1.2.1.2 Liquid preservatives
If appropriate, use the preservative without further preparation other than any necessary stirring. If it is a concentrate, dilute the preservative with the diluent to the required working concentration, using the procedure specified by the supplier.
Prepare a series of at least five concentrations by mass, distributed evenly about the expected toxic values. A solvent or diluent control, i.e. treatment at concentration = 0, shall also be used. If the approximate toxic values are unknown, the concentrations shall form a widely spaced geometric progression for a first test and a more closely spaced geometric or arithmetic progression for subsequent tests.
All treatment solutions shall be freshly prepared.
8.1.2.2 ImpregnatIon
Carry out impregnation in ascending order of concentration, starting with the solvent control (concentration = 0). The following procedure ensures the required complete impregnation of test specimens by the test solutions. For each concentration weigh each test specimen to the nearest 0,05 g, and then stack the test specimens in one of the treatment vessels (5.3.5) so that as much of their face as possible is exposed (e.g. by piling them crosswise). Ballast the stack of test specimens with weights (5.3.7) to prevent them from floating later when the liquid Is admitted.
Place each treatment vessel in one of the vacuum vessels (5.3.9), and reduce the pressure to 700 Pa. Maintain this for 15 mm. Observe the proper safety measures for vacuum vessels. After this period, close the stopcock to the vacuum pump (5.3.10) and open the other stopcock to allow the solution of preservative to be drawn Into the treatment vessel. Keep the test specimens covered completely by the solution throughout the remainder of the impregnation process.
Next, admit air to bring the vacuum vessel back to atmospheric pressure, remove the treatment vessel with its submerged test specimens from the vacuum vessel, cover It and leave it for 2 h, adding further solution if necessary to keep the test specimens fully covered by the liquid.
After this impregnation treatment remove the test specimens one by one, remove the excess liquid from their faces by lightly blotting with filter paper (5.2.5), and Immediately weigh to the nearest 0,05 g.
In the case of water-soluble preservatives, for example salts and organic chemicals which are being studied as active substances, calculate the mass of active matter retained by each test specimen from the mass of solution absorbed and its concentration.7)
In the case of organic formulations and organic water-dispersible formulations the retention is expressed for each test specimen in terms of the corresponding mass of the formulation retained but, if a concentration is supplied, the retention is expressed in terms of the solution prepared ready for use as specified by the supplier.
Calculate the mass of preservative retained per unit volume of wood in kilograms per cubic metre, for each test specimen.
8.1.3 Drying and conditioning of the test specimens after treatment8)
Arrange the impregnated test specimens treated with each preservative concentration on their narrow faces, resting on two glass rods, not touching each other in the drying vessel (5.3.6). Place the cover on the drying vessel. Place the drying vessel in the conditioning chamber (5.3.2). Invert the test specimens twice each week during the subsequent drying period, temporarily removing the cover to perform these operations.
To prevent mould growth on test specimens treated with water-diluted preservatives, place a small dish containing the xyiene (5.2.2) in the drying vessel (5.3.6).
During the first two weeks retain the cover on the drying vessel.
During the third week uncover the drying vessel progressively each day to allow the test specimens to dry steadily.
From the beginning of the fourth week leave the drying vessel fully open. Drying shall be complete at the end of the fourth week.
In the same way, place the test specimens impregnated with water-insoluble preservatives in the drying vessel for one week and then open it gradually throughout the second week. From the beginning of the third week leave the vessel fully open.
If, in case of slow drying products, the conditioning period is extended, the extended conditioning periods shall be stated in the test report.BS EN 117-2012 pdf download.
BS EN 117-2012 pdf download
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