Angle of repose drained

There is no standard procedure or equipment for measuring the drained angle of repose. The measurement is only relevant with 

The angle is expected to be affected by the degree of consolidation of the powder and its value, as expected, is usually greater than that of the poured angle of repose. It is clear that the measured values will be affected by the dimensions and size of the container used for the measurement, as well as by the way the powder is charged into it, and there is a need for developing a standard equipment and procedure for this test. 

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The drained angle of repose is the angle measured on or fl-om the conical surface of powder in a flat-bottomed container after the powder has been discharged or drained from the container via an orifice. 

The angle of repose may also be measured using a plane sheet to which is stuck a layer of particles from the powder. Loose powder is then poured on to the sheet which is then tilted until the powder slides. The angle of slide is known as the static angle of repose or the drained angle. 

An angle which is similar to the static angle of repose is the angle of slide which is measured in the same manner as the drained angle except that the surface is smooth and is not coated with a layer of particles. 

The collected solids must be periodically removed from the vessel thus, several drains may be placed along the length of a horizontal vessel. Since the solids will have an angle of repose of 45°-60°, the drains must be spaced at very close intervals and operated frequently to prevent plugging. The addition of sand jets in the vicinity of each drain to fluidize the solids while the drains are in operation... 

For applications that do not require a mass flow pattern the only condition is that the contents will eventually self-clear to be moved away by the screw. This less demanding type of flow pattern allows flared feeder casings to be designed on drained repose angles of the product. 

In addition to measurements of poured and drained repose angles, several other handling angles have been utilized. By placing the powder on a smooth surface... 

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