Dustiness definition

Hugo s approach can be extended without difficulty to apply throughout the whole range of pore sizes, but to accomplish this a specific and complete flux model must be used. To be definite we will assume that the dusty gas model is adequate, but the same reasoning could be applied to certain other models if necessary. The relevant flux relations are now equations (5.4). Applied to the radial flux components In one of our three simple geometries they take the form... 

Purchasing an old (secondhand) mattress is definitely not advisable. Such mattresses can be dusty or moist and can contain molds and old perfume particles. 

Much of the confusion arising in the interpretation of dust counts may be traced to an inadequate appreciation of their actual significance. Many investigators have ignored the limitations of the technique, used and this has caused severe criticism of such counts in evaluating a dusty, environment, particularly in attempts to comprehend the meaning of wide variations so often obtained in results. Therefore, what are the criteria which make dust counting definitely valuable ... 

To close the mass form of the dusty gas model, using a similar transformation procedure as employed for the mole based formulation, three novel definitions are required ... 

There is also a continuity equation for the host gas, usually considered as inert relative to the processes of (2.6,7). In addition, complete macroscopic specification would require the conservation equations of energy and momentum, which would be coupled to (2.6,7). The effects of turbulence can be introduced through stochastic definitions for the macroscopic variables of the system. This approach has been used in describing "dusty gas" flows [2.8] and in analysis of gas dynamics of expansion flows with condensation [2.4]. 

For other powder properties, such as bulk density, particle attrition, or dustiness, some standardized methods [160] exist that may serve as a guide to establishing a test method but may not be applicable in every case. For example, the dustiness of a material is a matter of definition, depending on the initial particle size of the tested product. If the determination of dustiness is combined with testing the attrition stability of the particles, the stress mechanism also has to be considered. Consequently, the methods for determining dustiness and particle attrition are mostly very specific to the product and the stress mechanism that is to be simulated [161]. In many other cases (e.g., solubility, moisture, and temperature sensitivity), no general standardized tests are available, and different approaches are nsed to describe the powder properties (see examples in Refs 110 and 162). 

To complete the transformation of the dusty gas model containing primed quantities into the un-primed variables associated with the aetual gas, one must employ the following definitions ... 

Experimental installation for a mechanical sampling at definition of a dustiness of gas on a method of an external filtering is shown in Figure 10.3. 

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