Location: GLO - Global
This dataset covers the treatment of undried timber with organic salt (Cu-HDO) with the oscillating pressure method.
Wood is not included in the dataset.
Pressure processes have been used for more than 150 years for impregnating wood with preservatives. The choice of the pressure process depends on the intended use, the nature and quality of the preservative, and the moisture level of the wood at the time of treatment.The oscillating pressure method was developed to impregnate green cordwood, particularly roundwood that is difficult to treat in the dry state. In this process, vacuum and pressure phases alternate, wheregy the phase changeover occurs in tess than a second. During the vacuum phases a small quantity of liquid is sucked out of the wood, and in the compression phases the salt solution is pressed in. As the impregnation period continues the pressure phases increase in lenght. For example, with green spruces, ca. 400 phase changes occur during the ca. 22-h impregnation process. Here the sap still present in the wood is continuously replaced by preservative liquid with an increase in the impregnation of the sapwood. For wood that is difficult to impregnate, the oscillating pressure method gives better impregnation and greated penetration depths than the vacuum-pressure method (also called full-cell or saturation impregnation method). Only water-borne preservaties are used.
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Depending on the use class envisaged for the treated timber, the following preservative inputs can be assumed (for softwood): use class 3: 6 kg/m3; use class 4: 8 kg/m3 (excluding uses with an expected service life > 15 years)
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In a variation of the oscillating pressure method, the usual vacuum phases are omitted (e.g. in the "Hamburg"-method). In intervals of minutes, pressure is produced slowly in the cyclinder, maintained for a short time, and then reduced to atmospheric again. The lenghts of the cycles is of the order of minutes and remains constant during the impegnation process. The number of cycles is considerably fewer than in the conventional oscillating pressure process. By usingt the air compressed in the wood, the sap is continually enriched and replaced by salt preservative solution.
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In principle, the process can be carried out in any pressure plant, provided that automatic plant control for cyclic pressure changes is available. The following figure provides a schematic of an oscillating pressure plant.
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Undefined unit processes (UPRs) are the unlinked, multi-product activity datasets that form the basis for all of the system models available in the ecoinvent database. This is the way the datasets are obtained and entered into the database by the data providers. These activity datasets are useful for investigating the environmental impacts of a specific activity (gate-to-gate), without regard to its upstream or downstream impacts.