Plastic Pentagon Ring vs Plastic Pall Ring: Which Random Packing Should You Select?

Plastic Pentagon Ring and Plastic Pall Ring occupy very different positions even when their nominal sizes are the same. DAIER's catalog-confirmed 38, 50 and 76 mm data show that Pentagon Ring provides much greater specific surface area and higher void fraction at every matched size, while Plastic Pall Ring provides a much lighter packed bed and substantially lower dry packing factor. 

This creates a clear engineering trade-off:

Plastic Pentagon Ring → much higher geometric contacting area + higher void fraction

versus:

Plastic Pall Ring → much lower dry packing factor + much lower packed-bed weight

The difference becomes larger—not smaller—as the nominal packing size increases.

Therefore the correct question is not:

Which plastic packing is generally better?

It is:

Does the tower need Pentagon Ring's unusually high area retention, or is Pall Ring's lower packing-factor and lower-weight position more important?

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1. Direct Answer

Evaluate Plastic Pentagon Ring more strongly when:

• high geometric surface area is important;
• the project wants a relatively large random packing without losing as much area;
• high catalog void fraction is attractive;
• packed-bed weight is acceptable;
• the process can tolerate its higher dry packing factor.

Evaluate Plastic Pall Ring more strongly when:

• lower dry packing factor is a major screening priority;
• a lightweight packed bed is important;
• conventional Pall Ring geometry is preferred;
• support load or freight matters;
• the process does not require Pentagon Ring's much greater geometric area.

The central distinction is:

Pentagon Ring retains area.

Pall Ring retains hydraulic simplicity and low bed weight.

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2. Direct Same-Size Comparison

The data are catalog-confirmed for these specific DAIER series. 

The overall pattern is unusually consistent:

Pentagon Ring wins surface area and void fraction.

Pall Ring wins dry packed-bed weight and packing factor.

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3. Pentagon Ring Has More Surface Area at Every Matched Size

The comparison is:

38 mm

Pentagon:

246 m²/m³

Pall:

151 m²/m³

50 mm

218 vs 100.

76 mm

198 vs 73.2.

Pentagon Ring therefore occupies a much stronger:

high geometric-area position

throughout the matched range.

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4. The Surface-Area Advantage Becomes Larger with Size

At 38 mm:

246 vs 151 m²/m³

Pentagon provides approximately:

63% more area.

At 50 mm:

218 vs 100

or approximately:

118% more area.

At 76 mm:

198 vs 73.2

or approximately:

170% more area.

So the relative gap grows dramatically.

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5. 76 mm Is the Most Striking Comparison

Both products belong to the:

76 mm nominal class.

Yet:

Plastic Pentagon Ring

198 m²/m³.

Plastic Pall Ring

73.2 m²/m³.

The Pentagon Ring provides approximately:

2.7 times the geometric surface area.

This shows why:

nominal size alone tells almost nothing about contacting-area density across different random-packing geometries.

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6. Why Pentagon Ring Preserves So Much Area

The representative Pentagon Ring geometry is low-profile and highly developed.

For example:

38 mm class

approximately 38 × 12 × 1.2 mm

50 mm class

approximately 50 × 17 × 1.5 mm

76 mm class

approximately 76 × 26 × 2.5 mm.

The element is not a conventional:

diameter × diameter ring.

Its developed geometry allows it to preserve a large amount of surface area per cubic meter.

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7. Pall Ring Uses a Fundamentally Different Element Proportion

Plastic Pall Ring is an open cylindrical ring-type packing.

Its geometry provides:

• wall openings;
• internal tongues;
• randomized bed orientation.

Pentagon Ring uses a much different:

• low-profile;
• multi-sided;
• developed-element

geometry.

Therefore the two should never be compared using only:

38 / 50 / 76 mm nominal size.

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8. Pentagon Ring Also Has Higher Void Fraction at Every Matched Size

The comparison is:

 

This is important because Pentagon Ring is not gaining surface area simply by creating a much denser, low-void bed.

It actually provides:

higher area and higher void fraction simultaneously.

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9. That Does Not Mean Pentagon Has Lower Packing Factor

This is where the comparison becomes especially valuable.

At all three matched sizes:

Pentagon Ring has the higher dry packing factor.

That means:

higher area + higher voidage does not automatically equal lower hydraulic packing factor.

The geometry of the element still matters.

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10. 38 mm Is the Closest Hydraulic Comparison

At 38 mm:

Pentagon Ring

260.3 m⁻¹.

Pall Ring

220 m⁻¹.

Pentagon's packing factor is approximately:

18% higher.

This is the smallest relative factor difference among the three matched sizes.

So 38 mm is where the two families are hydraulically closest by this catalog metric.

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11. But the 38 mm Area Difference Is Already Large

At the same size:

Pentagon

246 m²/m³.

Pall

151 m²/m³.

Pentagon gains:

95 m²/m³

of geometric area.

So the 38 mm decision can be framed as:

about 63% more area

for:

about 18% higher dry packing factor.

That may be an attractive trade-off in some clean contacting services.

But project operating conditions still determine whether it is useful.

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12. Pentagon Is Also Much Heavier at 38 mm

Bulk density:

Pentagon

112 kg/m³.

Pall

60 kg/m³.

Pentagon is approximately:

87% heavier per cubic meter.

For a 20 m³ bed:

Pentagon

2,240 kg.

Pall

1,200 kg.

Difference:

approximately 1,040 kg.

That is a significant structural and logistics difference.

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13. The 38 mm Packing Population Is Also Very Different

Pentagon

46,000 pcs/m³.

Pall

15,800 pcs/m³.

Pentagon contains approximately:

2.9 times as many individual elements per cubic meter.

This helps explain why it can maintain:

• high surface area;

but packing population should not itself be treated as a performance metric.

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14. 50 mm Creates a Much Stronger Separation

At 50 mm:

Plastic Pentagon Ring

• 218 m²/m³;
• 97% void;
• 107 kg/m³;
• 21,500 pcs/m³;
• 225.2 m⁻¹.

Plastic Pall Ring

• 100 m²/m³;
• 91.5% void;
• 44.5 kg/m³;
• 6,500 pcs/m³;
• 127 m⁻¹. 

At this size, the two products occupy very different engineering positions.

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15. Pentagon Has More Than Twice the Surface Area at 50 mm

Surface area:

218 vs 100 m²/m³.

Pentagon Ring provides:

118% more geometric area.

This is no longer a minor difference.

A 50 mm Pall Ring and a 50 mm Pentagon Ring should not be treated as equivalent:

“50 mm plastic tower packing.”

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16. Pentagon Also Has 5.5 Percentage Points More Voidage

Pentagon

97%.

Pall

91.5%.

Difference:

5.5 percentage points.

So Pentagon achieves:

• more than double the area;
• higher total free-volume percentage.

That can look overwhelmingly favorable if the comparison stops here.

But it should not stop here.

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17. 50 mm Packing Factor Strongly Favors Pall Ring

Pentagon

225.2 m⁻¹.

Pall

127 m⁻¹.

Pentagon's dry packing factor is approximately:

77% higher.

This is a much larger hydraulic-factor penalty than at 38 mm.

So the family ranking diverges as size increases.

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18. Why This Matters

A simplistic rule might say:

Higher void fraction should mean lower resistance.

The 50 mm data show why that is unreliable.

Pentagon has:

97% void

versus Pall:

91.5%.

Yet Pentagon also has the much higher:

225.2 vs 127 m⁻¹ dry packing factor.

Therefore:

free-volume percentage does not fully describe flow-path geometry.

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19. Void Fraction and Packing Factor Measure Different Things

Void fraction describes:

how much packed-bed volume is not occupied by solid material.

Dry packing factor reflects a broader geometric hydraulic position.

Element shape can influence:

• obstruction;
• surface orientation;
• flow-path complexity;
• interaction between neighboring elements.

Therefore:

high voidage and high packing factor can exist in the same packing.

Pentagon Ring is a clear example.

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20. 50 mm Pentagon Is More Than Twice as Heavy

Bulk density:

Pentagon

107 kg/m³.

Pall

44.5 kg/m³.

Pentagon is approximately:

2.4 times as heavy per cubic meter.

For a 30 m³ bed:

Pentagon

3,210 kg.

Pall

1,335 kg.

Difference:

approximately 1,875 kg.

That can materially affect:

• FRP tower supports;
• retrofit structures;
• freight.

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21. Packing Population Also Differs by More Than Three Times

Pentagon

21,500 pcs/m³.

Pall

6,500 pcs/m³.

Pentagon contains approximately:

3.3 times as many elements.

This contributes to its much more developed bed geometry.

But again:

packing count alone cannot tell whether the bed is hydraulically better or worse.

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22. 76 mm Produces the Largest Family Separation

At 76 mm:

Plastic Pentagon Ring

• 198 m²/m³;
• 96% void;
• 92 kg/m³;
• 6,500 pcs/m³;
• 207.1 m⁻¹.

Plastic Pall Ring

• 73.2 m²/m³;
• 92% void;
• 48 kg/m³;
• 1,930 pcs/m³;
• 94 m⁻¹. 

Here the two packings are almost different categories in terms of geometric density.

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23. Pentagon Has About 170% More Area at 76 mm

The comparison:

198 vs 73.2 m²/m³

means Pentagon provides around:

2.7 times the area.

This is one of the strongest reasons to consider Pentagon geometry where:

• large nominal packing size is required;
• but very low surface-area density is undesirable.

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24. Void Fraction Is Still Higher

Pentagon

96%.

Pall

92%.

Difference:

4 percentage points.

Again, Pentagon combines:

• much greater area;
• greater free-volume percentage.

But its packing factor remains much higher.

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25. 76 mm Pentagon Packing Factor Is More Than Twice Pall Ring

Pentagon

207.1 m⁻¹.

Pall

94 m⁻¹.

Pentagon's dry packing factor is approximately:

120% higher.

This is the largest relative gap in the matched size range.

So as size increases:

Pentagon's area-retention advantage increases

but simultaneously:

its packing-factor disadvantage also increases.

That is the core selection logic.

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26. The Trade-Off Becomes Stronger with Size

This creates a very useful engineering pattern:

The larger the matched size, the more strongly the two geometries diverge.

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27. Pentagon Is Also About 92% Heavier at 76 mm

Bulk density:

Pentagon

92 kg/m³.

Pall

48 kg/m³.

Difference:

44 kg/m³.

Pentagon is approximately:

92% heavier.

For a 30 m³ bed:

Pentagon

2,760 kg.

Pall

1,440 kg.

Difference:

approximately 1.32 tonnes.

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28. Packing Population Is Again More Than Three Times Higher

Pentagon

6,500 pcs/m³.

Pall

1,930 pcs/m³.

Pentagon contains approximately:

3.4 times as many elements.

Interestingly, the 76 mm Pentagon Ring contains:

6,500 pcs/m³

which is exactly the same catalog count as the:

50 mm Plastic Pall Ring.

Yet their physical bed properties are completely different.

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29. Same Piece Count Does Not Mean Equivalent Bed

Compare:

76 mm Pentagon

6,500 pcs/m³198 m²/m³96% void207.1 m⁻¹.

50 mm Pall Ring

6,500 pcs/m³100 m²/m³91.5% void127 m⁻¹.

They have the same packing population.

But Pentagon provides:

almost twice the surface area

and a much higher dry packing factor.

Therefore:

pieces/m³ cannot be used to identify hydraulic or mass-transfer equivalency.

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30. Which Is Better for High Surface-Area Priority?

Pentagon Ring clearly occupies the stronger geometric position.

At every matched size it provides:

• significantly more surface area.

The difference becomes extreme at:

• 50 mm;
• 76 mm.

This can be useful where:

• coarse nominal size is desired;
• but area retention remains important.

However geometric area does not itself guarantee:

• higher removal efficiency;
• lower HETP;
• better tower performance.

Actual process behavior still depends on wetting and operating conditions.

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31. Which Is Better for Low Packing-Factor Priority?

Plastic Pall Ring has the lower dry packing factor at every matched size.

The advantage is:

• moderate at 38 mm;
• large at 50 mm;
• very large at 76 mm.

Therefore Pall Ring generally deserves stronger screening where:

• pressure-drop margin;
• gas throughput;
• hydraulic simplicity

are dominant concerns.

Actual operating ΔP still requires tower conditions.

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32. Which Is Better for Lightweight Towers?

Plastic Pall Ring.

Its bulk density is substantially lower at all matched sizes:

• 38 mm — 60 vs 112;
• 50 mm — 44.5 vs 107;
• 76 mm — 48 vs 92 kg/m³.

Therefore Pall can be especially attractive for:

• FRP scrubbers;
• support-limited retrofits;
• freight-sensitive projects.

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33. Which Is Better for Fouling?

There is no universal answer.

Pentagon Ring provides:

• very high geometric area;
• developed geometry.

In clean service this can be valuable.

For severe fouling, however, more developed surface geometry can also create more places where deposits may accumulate.

Pall Ring's simpler geometry may deserve stronger screening in some fouling-sensitive services.

But neither packing should be described as:

• non-clogging;
• self-cleaning.

The fouling mechanism must be identified first.

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34. Which Is Better for Large-Diameter Packing Selection?

The question becomes especially interesting at 76 mm.

Pentagon preserves:

198 m²/m³

of surface area.

Pall falls to:

73.2 m²/m³.

If the process wants:

• a large element;
• while retaining high area;

Pentagon may be attractive.

If the objective is instead:

• low packing factor;
• lower dead load;

Pall has the stronger position.

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35. Tower Diameter Still Comes First

Before selecting:

• 38;
• 50;
• 76 mm,

confirm that the packing size is appropriate for the tower internal diameter.

Large packing in a relatively small column may create:

• stronger wall effects;
• too few elements across the cross-section.

The decision sequence should be:

Tower ID → Suitable Size → Pentagon vs Pall Geometry

not:

Choose the product family first.

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36. Do Not Replace Pall Ring with Pentagon Ring Like-for-Like

Suppose an existing tower contains:

50 mm Plastic Pall Ring

and a supplier proposes:

50 mm Pentagon Ring

as an “upgrade.”

That changes:

• area: 100 → 218 m²/m³;
• void fraction: 91.5 → 97%;
• bulk density: 44.5 → 107 kg/m³;
• pieces/m³: 6,500 → 21,500;
• dry packing factor: 127 → 225.2 m⁻¹.

This is:

a major geometry retrofit.

Not a routine replacement.

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37. Likewise, Pentagon → Pall Is Not a Simple Weight Saving

Replacing 50 mm Pentagon with 50 mm Pall would reduce:

• dry weight;
• packing factor.

But it would also reduce surface area from:

218 → 100 m²/m³.

That is more than:

half the geometric area removed.

The packed height and process duty may therefore need review.

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38. Same Packed Height Does Not Guarantee Equivalent Performance

A tower converted between these two families should not automatically retain:

the same bed height

and assume identical process performance.

Because the geometry changes substantially in:

• surface area;
• packing factor;
• population.

Review:

• required mass-transfer duty;
• gas flow;
• liquid flow;
• allowable pressure drop;
• tower diameter.

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39. Polymer Compatibility Is a Separate Decision

This article compares:

packing geometry.

The exact polymer still needs project-specific review.

Compatibility depends on:

• chemical species;
• concentration;
• operating temperature;
• solvents;
• oxidizers.

Do not assume that two “plastic” packings automatically have:

the same material suitability.

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40. Supplier Comparisons Should Use Exact Data

A meaningful comparison should include:

Do not reduce the decision to:

USD/m³.

The two products can represent very different packed beds.

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Decision Table

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Common Selection Mistakes

Assuming Higher Voidage Means Lower Packing Factor

Pentagon Ring disproves this at 38, 50 and 76 mm.

Assuming Same Nominal Size Means Similar Surface Area

At 76 mm:

198 vs 73.2 m²/m³.

Assuming More Surface Area Automatically Means Better Overall Performance

Hydraulic and process constraints still matter.

Assuming Pall Ring Is Simply a Lower-Area Version of Pentagon Ring

The two geometries occupy fundamentally different physical positions.

Ignoring Packed-Bed Weight

Pentagon Ring is substantially heavier at every matched size.

Using Pieces/m³ as an Efficiency Metric

Packing count does not directly define efficiency.

Using Void Fraction as a Pressure-Drop Predictor

Actual hydraulic behavior requires more than voidage.

Converting Packing Factor Directly into Operating ΔP

Actual gas/liquid conditions are required.

Switching Families During Routine Replacement

This is a retrofit.

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Frequently Asked Questions

Which has more surface area: Plastic Pentagon Ring or Plastic Pall Ring?

Plastic Pentagon Ring has substantially more verified surface area at every matched 38, 50 and 76 mm size.

How much more?

Approximately:

• 38 mm — 63% more;
• 50 mm — 118% more;
• 76 mm — 170% more.

Which has higher void fraction?

Plastic Pentagon Ring at every matched size:

• 38 mm — 95 vs 91%;
• 50 mm — 97 vs 91.5%;
• 76 mm — 96 vs 92%.

Which has lower dry packing factor?

Plastic Pall Ring at every matched size.

Which is lighter?

Plastic Pall Ring at every matched size.

What is the 50 mm comparison?

Plastic Pentagon Ring:

• 218 m²/m³;
• 97% void;
• 107 kg/m³;
• 21,500 pcs/m³;
• 225.2 m⁻¹.

Plastic Pall Ring:

• 100 m²/m³;
• 91.5% void;
• 44.5 kg/m³;
• 6,500 pcs/m³;
• 127 m⁻¹.

What is the 76 mm comparison?

Plastic Pentagon Ring:

• 198 m²/m³;
• 96% void;
• 92 kg/m³;
• 6,500 pcs/m³;
• 207.1 m⁻¹.

Plastic Pall Ring:

• 73.2 m²/m³;
• 92% void;
• 48 kg/m³;
• 1,930 pcs/m³;
• 94 m⁻¹.

Why can Pentagon Ring have both higher voidage and higher packing factor?

Because void fraction measures total free volume, while packing factor also reflects element geometry and flow-path characteristics.

Does Pall Ring necessarily have lower actual pressure drop?

Its dry packing factor is lower in the matched data, but actual pressure drop must still be evaluated using tower operating conditions.

Can Pentagon Ring directly replace Pall Ring?

Do not treat it as like-for-like. Surface area, dry bulk density, element population and packing factor can change dramatically.

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Selection Takeaway

Plastic Pentagon Ring vs Plastic Pall Ring is a particularly useful comparison because it separates three parameters that are often incorrectly treated as if they move together: surface area, void fraction and packing factor.

At 38 mm:

Pentagon → 246 m²/m³ / 95% void / 112 kg/m³ / 260.3 m⁻¹

versus:

Pall → 151 m²/m³ / 91% void / 60 kg/m³ / 220 m⁻¹.

At 50 mm:

Pentagon → 218 m²/m³ / 97% void / 107 kg/m³ / 225.2 m⁻¹

versus:

Pall → 100 m²/m³ / 91.5% void / 44.5 kg/m³ / 127 m⁻¹.

At 76 mm:

Pentagon → 198 m²/m³ / 96% void / 92 kg/m³ / 207.1 m⁻¹

versus:

Pall → 73.2 m²/m³ / 92% void / 48 kg/m³ / 94 m⁻¹. 

Across all three matched sizes:

Pentagon Ring provides both higher surface area and higher void fraction.

Yet simultaneously:

Pall Ring provides much lower dry bulk density and lower dry packing factor.

The family separation also increases with size.

At 38 mm:

Pentagon's area advantage is about 63%, while its packing-factor penalty is about 18%.

At 76 mm:

its area advantage grows to about 170%, while its packing-factor penalty grows to about 120%.

Therefore the two packing families become:

more different as size increases—not more similar.

The correct selection sequence is:

Tower Diameter → Suitable Size → Required Geometric Contact Area → Hydraulic Constraint → Bed Weight → Fouling → Compare Exact Pentagon / Pall Data → Polymer Compatibility → Internals Review

The key principle is:

Select Plastic Pentagon Ring when retaining unusually high geometric area is worth the additional bed weight and higher packing-factor position. Select Plastic Pall Ring when a lighter, lower-factor packed bed is more important. Never infer the winner from nominal size or void fraction alone.