Problems and Troubleshooting
Bridging
This is a phenomenon in which storage material adheres to the wall or is compressed in the vicinity of the discharge opening, preventing material in the upper part from flowing.
Elimination of Bridging
If the hopper discharge opening is small, bridging is likely to occur. Therefore, applying vibration to the hopper causes additional blockage. Especially note that rough crushed stone such as ore, sand high in water content, hygroscopic powders (ferric oxide, flour, lime, etc.) and deliquescent powders (salt, urea, ammonium sulfate, etc.) are rigidly compressed when humidity is high or the dew point is easily reached. The use of a blaster or knocker is suitable as a solution.
| Direct blaster |
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|---|---|
| Mini Mini blaster |
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| Mini Mini blaster |
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| Air knocker |
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| Ball vibrator |
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| Piston vibrator |
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| Vibration motor |
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Most suitable 
Suitable Somewhat suitableArching
This is a phenomenon in which compressed storage material in the upper part forms an arch-like balanced area and causes clogging, preventing material from flowing out.
Elimination of Arching
Arching is likely to occur in ores, powders with water content, adhesive powders (soybean powder, fish flour, casting sand, crushed sand, clay, etc.) and crushed stone. Ball vibrators/vibration motors/knockers/mini-blasters are suitable for small hoppers with a diameter up to 1 m, and vibration motors/knockers/blasters are suitable for mid-sized hoppers with a diameter of 1 m to 3 m. For large hoppers with a diameter greater than 3 m, vibration motors KM-4PAs/blasters are effective. If arching occurs in long-fibered materials or porous materials such as sawdust (wood powder) and rice bran, a large blaster is effective.
| Direct blaster |
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|---|---|
| Mini blaster |
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| Mini Mini blaster |
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| Air knocker |
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| Piston vibrator |
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| Vibration motor |
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Most suitable Suitable Somewhat suitableRatholing
Only the material in the tubular portion directly above the discharge opening flows, while the surrounding portion from the lower part to the upper part in the hopper does not move. As a result, newly input material flows out first, and old material remains as "dead stock." This phenomenon is called ratholing.
Elimination of Ratholing
Ratholing occurs when powders with high water content or adhesive powders are stored in a hopper with a cone angle larger than the response angle, when fine powders with less adhesion, high specific gravity, and relatively light weight (carbon black, PVC, calcium carbonate, talc, etc.) are stored, or when crushed sand (dust containing lime) is stored in a hopper such as a Colgate silo with a horizontal bottom. A blaster is typically suitable as a solution, and a vibration motor/knocker is effective for a small hopper.
| Direct blaster |
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|---|---|
| Mini blaster |
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| Mini Mini blaster |
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| Air knocker |
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| Ball vibrator |
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| Piston vibrator |
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| Vibration motor |
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Most suitable Suitable Somewhat suitableAdherence to Wall
Highly adhesive powders are likely to deteriorate over time depending on the weather and in particular on moisture or temperature differences. As a result, large-particulate powders adhere to the wall as residual material. This is the phenomenon of adherence to wall.
Elimination of Adherence to Wall
If adhesive or highly hygroscopic powders (lime, casting sand, clay, powdered coal, etc.) are stored in the hopper, adherence to wall may occur. A knocker is typically suitable as a solution, and combining it with a blaster is very effective in preventing potential adherence.
| Direct blaster |
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|---|---|
| Mini blaster |
|
| Mini Mini blaster |
|
| Air knocker |
|
| Ball vibrator |
|
| Piston vibrator |
|
| Vibration motor |
|
Most suitable Suitable Somewhat suitable