BS EN 275:1992 download.Wood preservatives Determination of the protective effectiveness against marine borers.
Introduction
BS EN 275 describes a marine test method which provides a basis for assessing the effectiveness of a wood preservative used to prevent attack of timber in sea-water by marine borers.
The method is only suitable for testing preservatives which are intended to prevent attack by marine wood-boring organisms of treated timber for use in more or less permanent contact with sea-water. It is not suitable for assessing the effectiveness of preservatives against microorganisms.
The main objective of the method described is to evaluate the relative effectiveness of a wood preservative applied by vacuum/pressure impregnation. For this reason permeable timbers are used throughout so that the protective efficacy of various retentions of the preservative can be determined.
However, it is recognized that modifications of the method may be used for other purposes, e.g. to determine the relative efficacy of a preservative treatment or to determine the natural durability of the heartwood and sapwood of a selected timber species.
The method is primarily intended for testing in temperate waters where teredine and Limnorid borers dominate. However, it is also capable of being used in the tropics where attack by pholads and specific crustacean borers may be very destructive.
The test is intended to run for a minimum period (5 years or until the point of failure) before any interpretation of the results can be made.
Variations in the test conditions can be expected from one test site to another depending on temperature, salinity, population density of the various borer species, etc. This will inevitably influence the general rate of attack. However, by comparing the results obtained for specimens treated with the test product with those obtained for specimens treated with a reference preservative and those obtained with untreated control specimens, the relative protective effectiveness of the product tested can be evaluated.
The procedures described in this standard method are intended to be carried out by suitably trained and/or supervised specialists. Appropriate safety precautions should be observed throughout the use of BS EN 275.
Removal of the test specimens from the water for inspection at regular intervals, with not more than 12 months between each inspection, and examination for marine borer attack, visually as well as by X-ray. The condition of the treated specimens is compared with that of untreated control test specimens and that of test specimens treated with a reference preservative, both of which indicate the aggressiveness of the individual site.
4 Apparatus
4.1 Ordinary laboratory equipment
4.2 X-ray apparatus, with tungsten target and beryllium window with voltage and current continuously variable in the following ranges:
Voltage: 10 kV to 50 kV Current: 0 mA to 15 mA.
4.3 Treatment plant, capable of impregnating the
timber (see 7.2).
5 Sampling
The sample of preservative shall be representative of the product to be tested. Samples shall be stored and handled in accordance with any written recommendations from the supplier.
NOTE For the sampling of preservatives from bulk supplies, the procedure given in EN 212 should be used.
6 Test specimens
6.1 Species of wood
For every test, the sapwood of Pin us sylvestris (Linnaeus) shall be used.
If additional wood species are to be used, they shall be susceptible to marine borer attack and the test specimens prepared from these species shall be capable of being completely penetrated with preservative.
NOTE It is recommended that a hardwood species of local relevance should be included if the preservative is expected to be used in hardwoods.
6.2 Quality of wood
The wood shall be of uniform growth, straightgrained and free from knots, cracks, stain, decay, insect holes or other defects. Test specimens of resinous appearance shall be avoided. The wood shall not have been water-stored, floated, chemically treated or steamed.
The Pinus sylvestris sapwood shall show an average rate of growth of 2,5 annual rings per 10 mm to 8 annual rings per 10 mm.
NOTE Additional specimens may also be included for chemical analysis in order to aid determination of retention andlor distribution of the preservative (see 7.3).
To assess the severity of the test site conditions a series of five untreated control test specimens are required per site. Further specimens shall be regularly installed at each site (see clause 9).
Include at each site two series of five standard reference specimens of Pin us sylvestris sapwood treated with a reference preservative (see clause 8) to at least two different retention levels according to 7.2.
6.5 Labelling of test specimens
Each test specimen shall be labelled in such a way that it can be identified, even after being exposed for a long time in sea-water.
NOTE 1 This can be done by fixing a small plate of a resistant metal to the specimen. Titanium or stainless steel with a perforated identification code can be used. Thereby the specimen can be immediately identified on the X-ray film (see Annex 13). NOTE 2 The label should be attached to the specimen by means of stainless steel ring, shank, nails or screws.
7 Conditioning and treatment of the
test specimens
7.1 Drying
The specimens shall be dried to a moisture content appropriate to the method of treatment.
7.2 Treating process
A full cell process shall be used for the reference specimens and, unless otherwise specified, for the test specimens. All specimens shall be spaced by means of stickers during treatment. Initial vacuum shall he less than 10 kPa pressure and maintained for at least :30 mm. Pressure of at least 1 MPa shall then be applied for at least 90 mm.
A description of the process, including pressure and vacuum details, together with the duration of each period shall be recorded for each charge.
7.3 Determination of retention of wood preservative
Calculate the volume of each specimen before treatment from its dimensions (see 6.3). Determine the mass of each specimen by weighing to the nearest 0,5 g.
After treatment allow the specimen to drain for several minutes or wipe off with a cloth excess solution from the surface. Reweigh each specimen to the nearest 0,5 g to determine the mass of treatment solution absorbed.
NOTE Additional specimens may also be included for chemical analysis in order to aid determination of retention andlor distribution of the preservative (see 7.3).
To assess the severity of the test site conditions a series of five untreated control test specimens are required per site. Further specimens shall be regularly installed at each site (see clause 9).
Include at each site two series of five standard reference specimens of Pin us sylvestris sapwood treated with a reference preservative (see clause 8) to at least two different retention levels according to 7.2.
6.5 Labelling of test specimens
Each test specimen shall be labelled in such a way that it can be identified, even after being exposed for a long time in sea-water.
NOTE 1 This can be done by fixing a small plate of a resistant metal to the specimen. Titanium or stainless steel with a perforated identification code can be used. Thereby the specimen can be immediately identified on the X-ray film (see Annex 13). NOTE 2 The label should be attached to the specimen by means of stainless steel ring, shank, nails or screws.
7 Conditioning and treatment of the
test specimens
7.1 Drying
The specimens shall be dried to a moisture content appropriate to the method of treatment.
7.2 Treating process
A full cell process shall be used for the reference specimens and, unless otherwise specified, for the test specimens. All specimens shall be spaced by means of stickers during treatment. Initial vacuum shall he less than 10 kPa pressure and maintained for at least :30 mm. Pressure of at least 1 MPa shall then be applied for at least 90 mm.
A description of the process, including pressure and vacuum details, together with the duration of each period shall be recorded for each charge.
7.3 Determination of retention of wood preservative
Calculate the volume of each specimen before treatment from its dimensions (see 6.3). Determine the mass of each specimen by weighing to the nearest 0,5 g.
After treatment allow the specimen to drain for several minutes or wipe off with a cloth excess solution from the surface. Reweigh each specimen to the nearest 0,5 g to determine the mass of treatment solution absorbed.