Measurement of Bulk Density

In recent years the compressibility index Ci( has become a simple, fast, and popular method of predicting powder flow characteristics [40,42-44,51,52]. Carr [42-44] proposed its use as an indirect measure of bulk density, size and shape,... 

To obtain a reliable measurement of bulk density, any widemouthed vessel with a capacity of 1 ft or more may be used. When such a determination must be made often, it is worthwhile to con-... 

Gamma ray attenuation Absorption of gamma rays passing through the sediment is caused by Compton attenuation (scattering), pair production, and by photoelectric absorption. The amount of gamma ray attenuation is a measure of bulk density, from... 

Measurements of bulk density and friction as described in Sections 3.4.1 and 3.4.2 have some relevance, as do the melt properties described in Section 3.6. However, apart from measurements of PVC gelation rates described in Section 3.7 using a torque rheometer. melting rate as a processability test appears to be quite unusual. 

SAINI G.R. 1966. Organic matter as a measure of bulk density of Soil. Nature (London), 210, 1295-1296. 

The formation density log is the main tool for measuring porosity. It measures the bulk density of a small volume of formation in front of the logging tool, which is a mixture of minerals and fluids. Providing the rock matrix and fluid densities are known the relative proportion of rock and fluid (and hence porosity) can be determined. 

Bulk density is easily measured from the volume occupied by the bulk solid and is a strong func tion of sample preparation. True density is measured by standard techniques using liquid or gas picnometry Apparent (agglomerate) density is difficult to measure directly. Hink-ley et al. [Int. ]. Min. Proc., 41, 53-69 (1994)] describe a method for measuring the apparent density of wet granules by kerosene displacement. Agglomerate density may also be inferred from direcl measurement of true density and porosity using Eq. (20-42). 

Conduct a lab test to measure the bulk densities of several filter aids. If you don t have the chemicals, then describe how you would do the tests and what specific measurements and calculations are needed. 

Tap density. The mass of particles divided by the volume after tapping the powder in a container. Also referred to as the drop density [61]. The volume measurement is similar to that of bulk density. 

Tap density (ptap) is an extension of bulk density measurements, and the procedure used to measure the tap density again varies from lab to lab and can affect the final results. To measure tap density, a graduated cylinder is filled with powder and the weight and volume are recorded. The difference observed between procedures is the number of taps used for the measurement. In some cases, a particular number of taps is used, such as 200 [65], 500 [66], or even 1000 taps [67]. Other procedures involve tapping the cylinder for a number of times, recording the volume, and repeating the procedure until the volume remains constant [68]. This method ensures more consistent results. 

In the equation s is the measured dielectric constant and e0 the permittivity of the vacuum, M is the molar mass and p the molecular density, while Aa and A (po2) are the isotope effects on the polarizability and the square of the permanent dipole moment respectively. Unfortunately, because the isotope effects under discussion are small, and high precision in measurements of bulk phase polarization is difficult to achieve, this approach has fallen into disfavor and now is only rarely used. Polarizability isotope effects, Aa, are better determined by measuring the frequency dependence of the refractive index (see below), and isotope effects on permanent dipole moments with spectroscopic experiments. 

Figure 4.2 A calibrated cell with a volume of 500 cm for measuring the bulk density of a resin feedstock at ambient temperature and pressure...

The bulk density of the pellets and the recycle material were measured at ambient conditions at 620 and 460 kg/m respectively. The device used to measure the bulk density is shown in Fig. 4.2. A mixture containing 80% pellets and 20% recycle material was estimated to have a bulk density of 590 kg/mh... 

Some important aspects of foam are not included in this list. We mentioned void volume earlier. This parameter is related to density by a comparison of bulk density to absolute density. We will discuss each of these measures of foam quality and relate their applicability to the theme of this book. Later in the chapter we will show how formulation and processing techniques are used to adjust and control the most important parameters. 

The method of product porosity measurement depended on the size of product particles. The porosity of granules for the size fraction dg < 4 mm was determined on the basis of bulk density measurement. The porosity of granules from a given size fraction was calculated from the formula... 

The behaviour of powders is often quite different from the behaviour of liquids and gases. Engineers and scientists are used to dealing with liquids and gases whose properties can be readily measured, tabulated and even calculated. With particle systems the picture is quite different. The flow properties of certain powders may depend not only on the particle size, size distribution and shape, but also on surface properties, on the humidity of the atmosphere and the state of compaction of the powder. These variables are not easy to characterise and so their influence on the flow properties is difficult to predict. In the case of particle systems it is almost always necessary to perform appropriate measurements on the actual powder in question rather than to rely on tabulated data. The measurements made are generally measurements of bulk properties, such as bulk density and shear stress. 

Bulk modulus has been calculated from first principles by a local-density approximation [19] and by a linear muffin-tin orbital method [10], suggesting a value B = 165 GPa. Measurements of bulk modulus in high-pressure induced rock salt phase yielded 170 GPa [20]. 

Other important physical measurements are bulk densities used to estimate hopper contents and circulation factors, and particle size analysis. The correct distribution of fine particles (30 - 180 microns) is essential to proper fluidization and transfer within the FCC unit. Generally, particles less than 30 microns are lost to the atmosphere or fines recovery system and are destined for a landfill. If the catalyst is too coarse, it may not circulate through the unit, necessitating a shutdown. Both problems are costly to the refiner and must be avoided. In addition, observation of particle size distribution changes at various points within the unit can pinpoint equipment malfunctions that might otherwise go undetected. 

Micrographs of the freeze-dried RDP preparations are shown in Figure 6. The unheated and microwave treated samples are clearly differentiated from those treated with hot water. The former consist of ragged fragments containing numerous but small pores while the latter appeared more aggregated and exhibits larger orifices. A consideration of bulk density (Table IV) and microstructure may help to explain some aspects of protein/water interaction properties. Porosity and particle size could be important parameters, however they are difficult to control and are rarely measured in studies of functional properties. 

Particle size and particle density measurements were made on partially burnt char particles which were collected in a cyclone separator at the exit of the reactor. Their burn-off was evaluated from a knowledge of char feedrate, gas flowrates and gas composition. The particle size of the collected material was determined by sieving particle density was derived from measuring the bulk density of a bed of particles in a manner described by Field ( ). 

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