Material Calculator - Funnel Diameter

Diameter of a Funnel. Calculator for the minimum diameter of a funnel for granular bulk material. If grains are to be filled using a funnel, the funnel must have a minimum diameter at its narrowest point, which depends primarily on the grain size. A smaller funnel diameter results in arching, meaning the grains interlock and block each other, preventing any flow through the funnel.
The diameter of the funnel should be at least 6 to 10 times the diameter of the grains. Therefore, the factor is preset to 8 times as the average value. This applies to smooth grains, such as glass beads or sand. If the grains are more cohesive, so if they are more prone to interlocking, for example due to rougher surfaces, large deviations from spherical shape, or moisture, a higher value is required. This is the case, for example, with grains and flour. Values ​​of up to 15 are required here.
For grains of different sizes, it is not sufficient to select their average diameter. In bulk solids technology, the d90 value is usually chosen, this is the diameter at which 90 percent of the grains are smaller and only 10 percent larger. In practice, this value can, of course, be difficult to determine and may need to be estimated.

If necessary, please adjust the factor, which is the ratio of funnel diameter to grain diameter. Enter one of the two diameters ​​to calculate the other value. The diameters are expressed in any length unit, such as millimeters, centimeters or inches, as long as they use the same unit.

For example, black peppercorns are relatively round and only slightly shriveled, so a good value for the factor here is 8. With a diameter of 5 millimeters per peppercorn, the funnel should have a minimum diameter of 40 millimeters, or 4 centimeters, if you want to fill them in a glass or something like this.