Figure 1: Plastic Pall Rings — PP, RPP, CPVC, and PVDF variants for corrosive service absorption and scrubbing.
Engineering Brief: When your tower runs below 100°C and handles corrosive aqueous streams, metal packings are overkill — and will corrode anyway. Plastic Pall Rings in PP, RPP, CPVC, and PVDF deliver void fractions above 90%, low pressure drop, and complete corrosion immunity at a fraction of the cost. Here's the complete specification.
The Pall Ring is the most widely used random tower packing in the world. It evolved from the Raschig ring: while retaining the cylindrical shape (height equals diameter), its wall is punched with two rows of windows, and the resulting tabs are bent inward toward the center . This simple geometric change transforms performance — the windows create internal wetting surfaces and open gas pathways that eliminate the severe channeling and high pressure drop that plague plain Raschig rings .
When molded from thermoplastics (PP, RPP, PVC, CPVC, PVDF), the Pall Ring becomes a lightweight, corrosion-proof, and economical random packing suitable for absorption, scrubbing, cooling, and stripping of non-oxidizing corrosive liquids and gases .
Figure 2: Punched windows and inward-bent fingers create internal wetting surfaces and open gas pathways.
The following data applies to standard PP Pall Rings. Other materials (RPP, PVC, CPVC, PVDF) share the same geometric dimensions, with bulk density varying by polymer density .
| Size D×H×T (mm) | Surface Area (m²/m³) | Void Fraction (%) | Bulk Number (pcs/m³) | Bulk Density (kg/m³) |
|---|---|---|---|---|
| 16 × 16 × 1.0 | 299 | 90.0 | 214,000 | 105 |
| 25 × 25 × 1.2 | 219 | 93.4 | 51,900 | 75 |
| 38 × 38 × 1.4 | 146 | 94.5 | 13,800 | 68 |
| 50 × 50 × 1.5 | 109 | 94.9 | 6,500 | 56 |
| 76 × 76 × 2.6 | 71 | 95.1 | 1,830 | 52 |
Data compiled from industry standard datasheets (geometric values; bulk density shown for PP, varies by material density). Custom sizes (10/13/89/100mm) and wall thicknesses available on request.
Choosing the right polymer is the single most important decision. The wrong material will warp, crack, or leach — use this table to match chemistry and temperature :
| Material | Max Temp (continuous) | Density (g/cm³) | Chemical Resistance | Typical Application |
|---|---|---|---|---|
| PP (Polypropylene) | 100°C | 0.89–0.91 | Excellent general-purpose | Water treatment, general scrubbing, cooling |
| RPP (Reinforced PP) | 120°C | 0.95–1.05 | Higher strength, retains shape | Hot alkaline scrubbing, deeper beds |
| PVC (Polyvinyl Chloride) | 60°C | 1.38–1.45 | Strong acids (H2SO4, HCl) | Chlor-alkali, HCl absorption (low temp) |
| CPVC (Chlorinated PVC) | 90°C | 1.45–1.58 | Hot acids and oxidizing media | Hot acid gas scrubbing, FGD |
| PVDF (Kynar) | 150°C | 1.75–1.78 | Superior (halogens, HF, solvents) | Chlorine, HF, ultra-pure, semiconductors |
Figure 3: Material selection — white PP/RPP, gray PVC/CPVC, and opaque PVDF for aggressive service.
Figure 4: Plastic Pall Rings (PP) installed in an acid gas scrubber for HCl and SO2 absorption.
| Factor | Plastic | Metal (SS316L) | Ceramic |
|---|---|---|---|
| Max Temperature | 60–150°C | ~400°C | ~800°C |
| Corrosion Resistance | Excellent | Moderate | Good (acid) |
| Bulk Density (kg/m³) | 52–105 | ~400 | ~700 |
| Relative Cost | Low | High | Medium |
| Best For | Corrosive aqueous, low–mid temp | High temp, hydrocarbons | High temp, strong acid |
Q: Which material should I choose for HCl gas absorption?
A: For dilute HCl at room temperature, PP is the economical choice. For concentrated or warm HCl, use CPVC (to 90°C) or PVDF (to 150°C). PVC is also excellent but limited to 60°C. See our material selection guide for chloride thresholds.
Q: Can plastic Pall Rings handle hot caustic (NaOH) service?
A: PP and RPP resist caustic well up to their temperature limits (100°C and 120°C respectively). Avoid PVC and CPVC in strong alkali — they degrade. For hot concentrated NaOH above 120°C, consider metal or ceramic packings.
Q: How much packing do I need for my tower?
A: Quantity (pcs) = Tower Cross-Sectional Area × Bed Height × Bulk Number (from table). Example: a 2 m ID tower with 3 m bed height of 38mm PP rings: π × 1.0² × 3 × 13,800 ≈ 130,100 pcs. Contact us with your tower dimensions for a precise quote.
FXSINO supplies Plastic Pall Rings in PP, RPP, PVC, CPVC, and PVDF in all standard sizes (16/25/38/50/76mm), with optional carbon-filled PP for anti-static service. Every order ships with material certificates and dimensional inspection reports. We also supply matched support grids and liquid distributors for complete tower packages.
Contact FXSINO: jackieqiu9202@gmail.com | +86 18507999558