Measurement Methods

Several methods have been used to measure the angle of repose of materials. Train (Ref 29) studied the angle of repose of a number of grades of glass spheres, lead shot, and silver sand using four different methods, as illustrated in Fig. 22. These methods are:

• Fixed height cone: The powder is carefully poured through a funnel at a fixed height until the apex of the heap formed by the powder reaches the tip of the funnel. The tangent of the angle of repose is the ratio of the height to the mean radius of the base of the powder heap.

• Fixed base cone: The powder is allowed to flow through a funnel, which is raised vertically until the heap covers a circular base of fixed size. The tangent of the angle of repose is calculated in the same manner as the fixed height cone method.

• Tilting table: A rectangular box filled with powder is tilted until the contents begin to slide. The angle that the upper surface of the box makes with the horizontal is equal to the angle of repose.

• Rotating cylinder: A sealed hollow cylinder half full of powder is rotated until the surface of powder exhibits its maximum angle with the horizontal. This maximum angle is the angle of repose.

Fixed height cone

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