- Flow Properties Of Powders describe how particles move, pack, and discharge in pharmaceutical processing.
- Flow Properties Of Powders affect mixing, granulation, tableting, and overall product quality.
- Powder flow is critical for operations like tablet compression, capsule filling, and granulation.
Methods to Evaluate Flow:
1 Angle of Repose
- Angle formed when a powder is allowed to fall freely and form a heap.
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$\tan \theta = \tfrac{h}{r}$
- Where:
- θ = angle of repose
- h = height of cone
- r = radius of base
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Interpretation:
| Angle (°) | Flow Characteristics |
| <25 | Excellent |
| 25–30 | Good |
| 30–40 | Passable |
| >40 | Poor |
2. Compressibility Index (Carr’s Index)
$\text{Carr’s Index} = \left( \tfrac{\rho_{\text{tap}} – \rho_{b}}{\rho_{\text{tap}}} \right) \times 100$
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Interpretation:
Index (
| Flow Properties |
|
| 5–15 | Excellent |
| 16–20 | Good |
| 21–25 | Fair |
| >25 | Poor |
3. Hausner Ratio
$\text{Hausner Ratio} = \tfrac{\rho_{\text{tap}}}{\rho_{b}}$
Interpretation:
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| Ratio | Flow Properties |
| 1.00–1.11 | Excellent |
| 1.12–1.18 | Good |
| 1.19–1.25 | Fair |
| >1.25 | Poor |
