Fluid classification

Fluids for Hydraulic Transmissions-Fire Resistant Fluids—Classifications, Provisional Recommendation RP7.7H, European Oil HydrauHc and Pneumatic Committee, 1976. 

Table 8.5 ISO 6743-4 1999 Hydraulic fluid classification for hydrostatic systems...

Elutriation. In fluid classification, various forces act to control the separation of dispersed particles. As discussed earlier, the kinetic behavior of particles is influenced by gravitation (as with elutriators) or centrifugal or Coriolis force (in classifiers). The medium is usually water or air. In general, all fluid classifiers can be divided into two classes counterflow equilibrium (elutriation) and inverse flow separation. Elutriation is discussed briefly below (8). 

Table 20.2. Fluid Classification Fluid type Description...

As was stated in the introduction, Stokes diameter jcst is usually used to characterize particle size in those applications where it is the behaviour of particles in liquids that determines the separation efficiency and other operational characteristics of the separators (e.g. in sedimentation, centrifugation and hydrocyclones). Methods that measure Stokes diameter, such as sedimentation or fluid classification, have therefore been used extensively in this field. Although preference is naturally given to wet methods, air classification is also widely used. 

Elutriation and fluid classification methods are also highly relevant to solid-liquid separation problems—they use the same or similar mechanisms for analysis as many separators. Use is made here of the size-dependent nature of dynamic separation processes and most of these methods are based on the analytical cut size defined in chapter 3, Efficiency of Separation . 

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