Pall rings were developed by BASF AG around 1940’s based on the raschig ring. They are still widely used in the industry owing to their good capacity characteristics at low- pressure drops. Punched windows on the outside facilitate better vapour flow and increase capacity as compared to raschig rings.
| Size | Wt. (Kg/ M³) | Surface Area (m²/m³) | Void Fraction % |
| 25 mm | 600 | 220 | 73 |
| 50 mm | 560 | 120 | 77 |
| 80 mm | 740 | 80 | 77 |
| 100 mm | 580 | 65 | 78 |