BS 8439:2005 pdf free.Continuous handling equipment and systems—Guide to properties of powders and bulk materials.
BS 8439 Ifit is necessary to quote the bulk density exclusive of moisture, the term “dry bulk density”should be used.If bulk densities exclusive and inclusive of moisture are being quoted in the same context, the latter shouldbe termed “wet bulk density” in order to avoid confusion.
The usual method for measuring bulk density is to fill a container of known volume with the given powderor bulk material (under as poured or compacted conditions as appropriate),level-off the upper surface andmeasure the total mass. Knowing the mass stored in the container, the bulk density which is derived bydividing the mass of powder or bulk material by the volume of the container.Further information onmeasuring methods for bulk density is given in BS 812-2,BS 6147,BS 1016-108.3, BS 1016-108.4 andBS 1460.
The relative density of a powder or bulk materialis the ratio of the particle density (see 5.3.1) to the densityof water. It is identical to “specific gravity”. The particle density may be calculated with the volume measured inclusive or exclusive of open and closed pores.Further information on relative density is givenin Wilkinson et al.[6] and Svarovsky [7].Liquid pyknometry should be used to measure the relative density of powders and bulk materials.
Watertight containers are used to weigh water and the powder or bulk material under test. However if thematerial reacts with(or dissolves in) water, a non-reactive liquid should be used.Further informationregarding the relative density of powders and bulk materials when applied to specific powders or bulkmaterials is given in BS 812-2,BS 1016-108.5 and BS 1377-2.The sum of these values is termed the total moisture content.
The surface or free moisture content can have a major effect (for example, alteration to bulk density andstrength) on some of the flow properties of the material, for example angle of internal friction and unconfined yield stress.In a materials handling context, unless otherwise stated, moisture content isdefined on a wet basis.Where the material has a wide particle size distribution, the fines fraction (i.e.less than 850 um) holds themost moisture. For example, for coal passing through a 20 mm sieve at an average wet weight moisturecontent of 9 %, the amount retained on a 6.3 mm sieve might have a surface moisture content of the orderof 5 % whilst the amount passing through this sieve might have a surface moisture content of the order of20 % as shown in Figure 3.BS 8439 pdf download.