Failures to discharge from silos or hoppers mainly occur as a result of two different types of blockage: stable arching or rat-holing.

In both cases the strength of the bulk solid is higher than the gravitational stresses, meaning that the structures are stable. The stresses in these structures increase as the size of the arch or rat-hole increases, hence it follows that if the outlet size of the hopper is continually increased, there will eventually arise a situation where the gravitational stresses overcome the strength of the material and the structure collapses, allowing flow to occur.

Consequently, for a silo to discharge successfully by gravity, without flow aids, the outlet size should be very large.

The most cost effective solution to resolve discharge problems in silos is actually to fluidise powders in order to promote flow by insufflating low pressure air.

At INGESOA® we dispose of a wide range of valves capable of discharging silos in a simple and clean way with an easy access for maintenance purposes.