EN 252-2014 pdf download.Field test method for determining the relative protective effectiveness of a wood preservative in ground contact.
least 30 mm. Pressure of at least 1 MPa (10 bar) shall be applied for at least 90 mm. Complete records of treatment shall be made for each charge.
5.3 Determination of retention of wood preservative product
Calculate the volume of each stake before treatment from its dimensions (see Clause 3). If shaped to a point before treatment this shall be taken into account in the calculation.
Determine the mass of each stake by weighing to the nearest 0,5 g.
After treatment, allow the stake to drain for several minutes, Reweigh each stake to the nearest 0,5 g to determine the mass of treatment solution absorbed.
Calculate the retention value of each stake from the mass of treatment solution absorbed, the concentration of the treating solution and the calculated stake volume. Express the retention of the wood preservative product as kilograms per cubic metre of wood. Calculate the mean retention for each series of test stakes.
Stakes with individual retentions deviating by more than 10 % from the mean value shall be rejected.
5.4 Range of preservative retention
Test each preservative with at least three and preferably five different retention levels. These different levels shall be achieved by using fresh preservative solutions at different dilutions and without varying the treatment conditions.
Use a fresh solution at each dilution; the dilution of a quantity of solution which has been used already may be unsatisfactory because preferential absorption may have occurred during the previous treatment schedule.
5.5 Post treatment conditioning of stakes
For those products requiring a fixation period the recommendations of the wood preservative manufacturer should be followed.
For the reference preservatives the stakes shall first be close-stacked, each retention group separately, and kept wrapped for an appropriate period (at least 3 weeks) at room temperature (above 15 °C) in polyethylene or similar non water permeable material to avoid rapid drying.
For drying after fixation, make open piles protected from rain and frost, with inert spacers to allow air flow between the stakes.
Stakes of the same type (preservative and retention) shall be distributed across the test plot. An example of a distribution pattern is given in informative Annex C.
The stakes shall not be hammered down into the soil, since this may damage the wood (fractures, splits) and influence the test results
NOTE 2 A spike, spade or other convenient tool can be used to make a suitable hole in the ground.
Having inserted the stake in the hole it is important to press the surrounding soil tight to the stake so that a
good contact is achieved between the soil and all the surfaces of the buried half of the stake.
10 Inspections
The stakes shall be examined annually. Inspections after a long dry period should be avoided. However, inspection during rain should be avoided as this also makes evaluation difficult.
Withdraw the stake from the ground by a straight upward pull and remove carefully the soil adhering to it while ensuring that the stake and its test position are not unduly damaged. Should the stake be difficult to withdraw, gentle waggling and tapping perpendicular to the narrow plane of the stake is permissible.
Examine all sides of the stake for the presence of symptoms of changes in the wood. It is not necessary to use magnification.
To determine any change in surface hardness of the wood a blunt pointed instrument can be used for probing.
However, the stake should be inspected without undue mutilation or removal of softened wood as this would destroy the surface of the wood and alter the test conditions.
The stakes shall be rated according to Clause 11. In case a rating 3 is recorded, a light blow on one of the 50 mm wide face shall be administered in order to assess if a rating 4 is appropriate.
If possible, the type of decay shall be recorded. These include white and brown rot, soft rot and bacterial attack.
After the inspection the stake is carefully re-installed into its original hole, The soil is carefully pressed against it so that a good contact Is ensured between the soil and the surfaces of the buried part of the stake. The half of the stake that had been in the ground before shall be inserted again.
Other examinations, e.g. bending tests under carefully controlled conditions, may be carried out at these intermediate times (see informative Annex D).EN 252-2014 pdf download.