Discharge cone

The discharge cone is the converging lower section of a hopper or silo that funnels stored material to the outlet. The cone's geometry — angle from vertical, surface finish, outlet diameter — is the single most important design variable controlling whether the vessel delivers mass flow or funnel flow.

Design rules of thumb

• Steeper cone (smaller angle from vertical) — more likely to deliver mass flow
• Smoother wall finish — less friction at the wall — more likely mass flow
• Larger outlet diameter — greater margin against bridging
• Outlet at least 6× the largest particle dimension — minimum to avoid interlocking

For cohesive powders, the cone needs to be steeper than 70° from horizontal and the wall finish must be smoother than the material's wall-friction angle to achieve mass flow.

Acoustic-cleaning duty

Sonic horns are most commonly mounted on the cone wall — either through a side flange just below the vessel cylinder or at the cone-to-cylinder transition. This positions the horn close to the most arching-prone zone while keeping it accessible for maintenance.

Related terms

• Hopper
• Silo
• Mass flow vs funnel flow
• Bridging
• Sonic horn