Glossary
Hoppers and silos
Anti-bridging device
Also known as anti-arching device, flow promoter, flow aid.
Anti-bridging device is the generic procurement term for any flow-aid hardware installed to prevent or break bridging, rat-holing and other discharge stoppages in a hopper or silo. The category covers a range of technologies with overlapping use cases.
Anti-bridging device families
| Family | Mechanism | Best suited to |
|---|---|---|
| Sonic horn | Continuous acoustic vibration | Most powders, especially cohesive Class-C; non-contact |
| Air cannon / air blaster | Periodic high-pressure pneumatic blast | Hard bridges, large silos, established practice |
| Bin vibrator | Continuous mechanical or pneumatic vibration | Small bins; can compact wet material |
| Fluidisation pad | Aerates the lower bed | Dry, fluidisable powders |
| Whip hammer | Manual impact | Legacy practice; HSE concerns |
| Mechanical extractor | Bypasses the discharge | Continuous-flow processes |
Selecting a device
Selection depends on material properties (Geldart class, moisture, temperature), vessel geometry and operating mode. Sonic horns are increasingly the default specification because they cause no structural stress, work continuously, and integrate cleanly into existing control systems.
Related terms
Related terms
- Bridging (bulk-solids)Bridging (also arching) is the formation of a stable arch of bulk solids above the discharge outlet of a hopper or silo, stopping material flow. The universal failure mode of bulk-solids storage.
- HopperA hopper is an inverted-pyramid or conical vessel for storing and discharging bulk solids. Bridging and rat-holing are the universal failure modes; sonic horns are a clean, low-maintenance remedy.
- SiloA silo is a large vertical bulk-solids storage vessel. Cement, fly-ash, lime, biomass, fertilizer and food-powder silos all bridge and rat-hole; sonic horns are the leading flow aid.
- Sonic hornA sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.
- Air cannonAn air cannon is a pressure-vessel and quick-release-valve assembly that fires a brief high-pressure air pulse into a hopper or silo to break material bridges. Effective but causes structural stress.
- Bin vibratorA bin vibrator is a pneumatic or electric vibrator bolted to the outside of a hopper or silo to dislodge bulk-solids bridges. Compact but can compact wet powders and stress the vessel.
- Material flow promotionMaterial flow promotion covers the design and equipment choices that keep bulk solids moving reliably out of storage and process vessels. Sonic horns are an increasingly common solution.