BS EN 14780:2011 pdf download

BS EN 14780:2011 pdf download.Solid biofuels-Sample preparation.
NOTE For very large sample sizes, it is more practical to use a push dozer or bdozer or any other heavy machinery that has a large scoop th raised edges.
6.2 Apparatus for particle size-reduction
CAUTiON — When analysing metals, take care that there is no contamination from the sample preparation or reduction equipment.
6.2.1 Coarse cutting mill or wood crusher
Coarse cutting mills are used for cutting materials into lengths of about 10 mm to 30 mm (depending on the blot uel and the analyses to be pertormed) Drying of the material during coarse cutting should be avoided, by limiting heat production and air flow through the material. The equipment shall be designed so that it does not lose dust or contaminate the material with peeces of metal, and shall be easy to clean.
NOTE To p event losses of moisture during particle size reduction a gnnder with as low a grinding speed as poss,le is preferred.
6.2.2 Cutting mill
Cutting mitts are used for reducing the nominal top size of materials used as blofuels from about 10 mm to 30 mm down to about 1 mm of less (depending on the bofuel and the analyses to be performed). The mill shall be provided with screens of various aperlure sizes covering this range, including an appropnate sieve to control the nominal lop size of the material produced. Other apparatus may be used provided that they are designed so that they do not get blocked with the material that Es being processed. Avoid the use of cutting mills whose cutting faces contain significant quantities of an element that is to be determined in the analysis.
NOTE Cross beater mills can be used without any excessive dusbng. when titled with dust filLers (like a tiller sock) between the mill and the receiving container They are suitable icr final grinding of hard, wood type materials after the progflnding with cutting type mills.
6.2.3 Axe
An axe is used for cutting wood logs or coarse material down to maximum 30 mm thidness or suitable size to be processed rn a cutting mill provided witti a 30 mm sieve.
6.2.4 Hand saw
A hand saw is used to saw off wood logs or coarse material down to maximum 30 mm thickness or suitable size to be processed in a cutting mill provided with a 30 mm sieve.
NOTE A chain saw may contaminate the sample by chain ad and should therelore not be used. A saw mactàe should not be used tor size rec)jclion to avoid the risk of losing moisture in the sample as a resuh of heat caused by fricbon.
6.3 Sieves
A wire-mesh sieve with an aperture size of 100 mm is required to check the nominal top size of general analysis samples. A wire-mesh sieve with an aperture size of 0,25 mm will be required ii sub-samples with this nominal top size are required.
6.4 Balance
A balance is required that is capable of determining the mass of samples to an accuracy of 0,1 % of the sample mass, and the mass of sub-samples to an accuracy of 0,1 % of the sub-sample mass.
7 Sample reduction — general prlndples
For every sample division stage to be carried out his important that a sufficient mass of matenal is retained, otherwise the sub-samples produced or the test portions to be taken may not be representative Of the original sample. Table 1 gives a guideline for minimum masses to be retained after each sample division stage, depending on the nominal top size of the material. In addition to the minimum masses stated in Table 1 it shall be ensured that the mass after a sample division stage is suffientty large for the actual test or tests to be performed, Supplementary requirements concerning the masses of the test portions are given in European Standards for test methods of solid biofuels.