Angle of fall

Fall-werk, n. drop machine stamp pile driver. -wiokel, m. angle of inclination angle of fall, -ziinder, m. percussion fuse. 

Sliding Rod Impact Test. In Ref 36 is a table of heights of fall for 50% expls listed against sample size and angle of fall extreme values are 0.2cm for 3mg sample at 75°, and 25.5cm for 62mg at 30° angle... 

The floodability index was calculated from the dispersibility, cohesion, angle of fall, and flowability index parameters. The values for this property ranged from 55 to 76. The most floodable material was lot 4405K5, and the least floodable material lot was the instant sorbitol, which is in agreement with the flow index and the particle size data. The... 

Bulk density packed, Pbdp Angle of fall... 

Fig. 3 The angle-of-repose plate incorporates a protractor, an indicator wire, and a jarring device for angle-of-fall tests. (From Chem. Engi. 1965, 18, 164.)...

Other classification systems are used less frequently. Carr " also devised a system to classify materials as to their floodability. He defines the floodability of a material as its tendency to flow like a liquid because of the natural fluidization of a mass of particles by air. In order to so classify a material, the flowability is determined utilizing the method just described. This value is equivalent to a measurement Carr calls the angle of fall, angle of difference, and dispersibility. Though referred to in any of the papers mentioned here, this system is much less utilized then the flowability measurements. Geldart reported on a characterization system of powders according to their ability to aerate and later Molerus modified this system. In a more recent symposium this method of powder classification was examined. ... 

Carr describes36 an angle-of-repose plate which incorporates a protractor, indicator wire and a jarring device (the jarring device is used to measure the angle of fall, see below). 

The above-defined angle of fall is a rather poor measure of floodability, however, and is very rarely used in this country the definition of the measurement conditions is also poor, particularly of the jarring, and the tested values are certain to depend on the mass and the kind of support of the base plate of the instrument. 

Figure 1.9 Apparatus for the measurement of angle of repose, angle of fall and angle of difference (Carr 1965a).

The difference between the angle of repose and the angle of fall gives an indication of the potential floodability of materials. The greater the angle of difference the better the flowability, fluidisability and floodability. 

Test A - Measurement of Carr angle of repose Test B - Measurement of Carr angle of fall Test C - Calculation of Carr angle of difference Test D - Measurement of Carr loose bulk density Test E - Measurement of Carr packed bulk density Test F - Calculation of Carr compressibility Test G - Measurement of Carr cohesion Test H - Measurement of Carr uniformity Test I - Measurement of Carr angle of spatula Test J - Measurement of Carr dispersibility... 

When powders flow, they do so either in a steady controlled fashion (as in the case of dry sand), or in an uncontrolled gushing manner (as would damp sand, for which the entire bulk tries to move in a solid mass). This latter condition is termed floodable flow, and is most characteristic of the flow of cohesive, sticky powders. The floodability of a powder is determined by its overall flowability (the determination of which has just been described), the angle of fall (obtained as the new repose angle when the powder cone is mechanically shocked), the dispersibility (ability of a given powder to become fluidized), and the angle of difference (obtained as the numerical difference between the angle of fall and angle of repose). 

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