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

Plastic Pall Ring and Plastic Cascade Mini Ring are both widely applicable plastic random-packing geometries, but neither family has a universal physical advantage. DAIER's catalog-confirmed 16, 25, 38, 50 and 76 mm-class data show that the relative ranking of surface area, void fraction and dry packing factor changes repeatedly as size increases. 

The selection question is therefore not:

Is Cascade Mini Ring a better version of Pall Ring?

It is:

At the required packing size, which geometry provides the right balance of geometric surface area, bed openness, dry packing factor, packed-bed weight and fouling tolerance?

This distinction matters because the answer at:

• 16 mm;
• 38 mm;
• 50 mm

is not the same.

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1. Direct Answer

Choose Plastic Pall Ring more readily when:

• a conventional and widely understood random-packing geometry is preferred;
• existing Pall Ring operation is already proven;
• like-for-like replacement minimizes risk;
• the selected Pall size has the better surface-area or packing-factor balance;
• simple open-wall geometry is desirable.

Evaluate Plastic Cascade Mini Ring more strongly when:

• compact low-height element geometry is attractive;
• the selected size provides useful additional surface area or voidage;
• a retrofit is intended to alter hydraulic geometry;
• reduced dry bed weight is valuable in the applicable size class.

The key rule is:

Select by exact size data—not by family reputation.

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2. DAIER Same-Size-Class Data

The catalog-confirmed series allow direct comparison through the common 16, 25, 38, 50 and 76 mm classes. 

This is not a one-direction comparison.

The winner changes depending on which parameter matters.

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3. 16 mm Strongly Favors Cascade Mini Ring for Surface Area

At approximately 16 mm:

Plastic Pall Ring

320 m²/m³.

Plastic Cascade Mini Ring

370 m²/m³.

Cascade Mini Ring provides:

50 m²/m³ more geometric surface area

or approximately:

16% more. 

That can be attractive where a fine bed is selected specifically for high geometric contacting area.

But that additional area comes with important hydraulic and mechanical trade-offs.

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4. 16 mm Pall Ring Has Higher Void Fraction

At the same size class:

Pall Ring

88%.

Cascade Mini Ring

85%.

Pall Ring therefore has:

3 percentage points more void fraction.

That is meaningful in such a fine random-packing bed.

So already:

CMR → more area

while:

Pall Ring → more free bed volume.

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5. 16 mm Cascade Mini Ring Has Much Higher Packing Factor

Dry packing factor:

Pall Ring

376 m⁻¹.

Cascade Mini Ring

602.6 m⁻¹.

The difference is substantial. 

This means the extra CMR geometric area comes with a much higher dry packing-factor position.

Do not translate this directly into a specific operating ΔP difference.

Actual pressure drop still depends on:

• gas flow;
• liquid flow;
• tower diameter;
• fluid properties;
• packed height.

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6. 16 mm CMR Is Also Heavier

Dry bulk density:

Pall Ring

108 kg/m³.

CMR

135.6 kg/m³.

For 10 m³ of packing:

• Pall ≈ 1,080 kg;
• CMR ≈ 1,356 kg.

The difference is approximately:

276 kg of dry packing.

So in this smallest size class, CMR's higher area is accompanied by:

• lower voidage;
• higher packing factor;
• higher dry bed weight.

That is a very clear trade-off.

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7. Why CMR Contains Many More Pieces at 16 mm

Packing population:

Pall Ring

214,000 pcs/m³.

CMR

299,136 pcs/m³.

CMR contains roughly:

40% more individual elements.

Its element proportions are also different.

The verified CMR entry uses approximately:

16 × 8.9 × 1 mm

rather than the roughly equal-height:

16 × 16 × 1 mm

Pall Ring geometry. 

So even the same nominal width does not mean the elements occupy the same geometric form.

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8. 25 mm Is Much More Balanced

At 25 mm:

Pall Ring

• 213 m²/m³;
• 90% void;
• 68 kg/m³;
• 53,500 pcs/m³;
• 285 m⁻¹.

Cascade Mini Ring

• 228 m²/m³;
• 90% void;
• 65 kg/m³;
• 81,500 pcs/m³;
• 312.8 m⁻¹. 

This is a very different comparison from 16 mm.

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9. 25 mm Has Exactly the Same Void Fraction

Both products provide:

90% void fraction.

That allows the geometry comparison to become clearer.

CMR provides:

• higher surface area;
• slightly lower dry bulk density.

Pall Ring provides:

• lower packing factor;
• much lower element population.

So at 25 mm the selection is essentially:

more geometric area

versus:

lower packing-factor geometry.

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10. Surface-Area Gain at 25 mm Is Modest

CMR:

228 m²/m³.

Pall Ring:

213 m²/m³.

Difference:

15 m²/m³

or about:

7%.

That is useful, but nowhere near the large 16 mm difference in packing factor.

Therefore an engineer should ask:

Is approximately 7% more geometric surface area worth moving from 285 to 312.8 m⁻¹ dry packing factor?

The answer depends on tower duty.

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11. CMR Is Slightly Lighter at 25 mm

Bulk density:

Pall

68 kg/m³.

CMR

65 kg/m³.

Only:

3 kg/m³

separates them.

So packed-bed weight is unlikely to be the main reason for choosing between these two 25 mm products.

The important variables are:

• area;
• packing factor;
• element geometry.

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12. 38 mm Reverses the Surface-Area Ranking

At 38 mm:

Pall Ring

151 m²/m³.

Cascade Mini Ring

132.5 m²/m³.

Now Pall Ring provides:

18.5 m²/m³ more geometric area.

This is important because CMR had the higher surface area at:

• 16 mm;
• 25 mm.

By 38 mm:

the ranking has reversed.

This alone disproves any universal claim that Cascade Mini Ring always provides higher specific surface area.

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13. 38 mm Has the Same Void Fraction Again

Both provide:

91% void fraction.

But packing factor moves in the opposite direction from surface area:

Pall

220 m⁻¹.

CMR

175.8 m⁻¹. 

So 38 mm creates perhaps the clearest trade-off of the whole series:

Pall Ring → More Surface Area

CMR → Lower Dry Packing Factor

with:

the same catalog void fraction.

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14. Why the 38 mm Comparison Is So Valuable

It isolates geometry.

The two products have identical:

91% void fraction.

Yet:

• surface area differs by about 14%;
• packing factor differs by about 20%.

Therefore:

total free volume alone cannot define packed-bed hydraulic geometry.

The internal shape and orientation of the packing elements matter.

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15. CMR Is Slightly Lighter at 38 mm

Pall

60 kg/m³.

CMR

54 kg/m³.

Difference:

6 kg/m³.

CMR also contains far more pieces:

• 27,200 vs 15,800 pcs/m³.

Yet it still has:

• lower bulk density;
• lower packing factor.

Again:

packing population is not a reliable proxy for bed weight or hydraulic resistance.

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16. 50 mm Reverses the Ranking Again

At 50 mm:

Pall Ring

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

CMR

• 114.2 m²/m³;
• 92.7% void;
• 43 kg/m³;
• 10,740 pcs/m³;
• 143.1 m⁻¹. 

Now CMR simultaneously provides:

• higher surface area;
• higher void fraction;
• slightly lower bulk density.

But Pall Ring still has the lower packing factor.

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17. 50 mm Is a Great Warning Against Single-Parameter Selection

CMR looks stronger in three obvious catalog metrics:

Area

114.2 vs 100 m²/m³.

Voidage

92.7 vs 91.5%.

Dry Weight

43 vs 44.5 kg/m³.

Yet dry packing factor is:

CMR

143.1 m⁻¹.

Pall

127 m⁻¹.

Therefore:

more area + more voidage + lower weight still does not automatically mean lower packing factor.

These metrics describe different aspects of geometry.

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18. What Does Pall Ring Gain at 50 mm?

Pall Ring gives up:

• approximately 14% surface area;
• 1.2 percentage points of voidage.

But it occupies the lower:

dry packing-factor position.

That may matter when:

• allowable pressure drop is tight;
• gas throughput is important.

Actual tower hydraulics still require process data.

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19. 76 mm Shows the Same Broad Pattern as 50 mm

At 76 mm:

Pall Ring

73.2 m²/m³92% void48 kg/m³1,930 pcs/m³94 m⁻¹.

Cascade Mini Ring

90 m²/m³92.9% void44 kg/m³3,420 pcs/m³112.3 m⁻¹. 

Again CMR provides:

• more surface area;
• more voidage;
• lower bulk density.

But Pall Ring provides:

• lower dry packing factor.

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20. CMR Surface-Area Advantage Becomes Significant Again at 76 mm

Surface area:

Pall

73.2 m²/m³.

CMR

90 m²/m³.

Difference:

16.8 m²/m³

or approximately:

23% more for CMR.

That is significant.

So for a coarse large-size bed, CMR may retain considerably more geometric contacting area.

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21. Void-Fraction Difference at 76 mm Is Small

Pall

92%.

CMR

92.9%.

Only:

0.9 percentage point

separates them.

Therefore the larger distinction is between:

• CMR's additional geometric area;
• Pall Ring's lower packing factor.

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22. CMR Is Also Slightly Lighter at 76 mm

Bulk density:

Pall

48 kg/m³.

CMR

44 kg/m³.

For a 30 m³ bed:

• Pall ≈ 1,440 kg;
• CMR ≈ 1,320 kg.

Difference:

about 120 kg.

This is useful but not normally as decisive as the geometry and hydraulic position.

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23. Full-Series Surface-Area Ranking

The ranking reverses at 38 mm and reverses back again at 50 mm. 

Therefore:

Product family alone cannot predict specific surface area.

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24. Full-Series Packing-Factor Ranking

This is even more interesting.

CMR has the lower dry packing factor only at:

38 mm

within this matched series.

So the statement:

“Cascade Mini Ring always has lower packing factor than Pall Ring”

would be wrong.

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25. Why 38 mm Is the Outlier

At 38 mm:

• CMR area is lower;
• factor is lower;
• voidage is identical.

This suggests the 38 mm CMR geometry occupies a particularly different balance:

less geometric area in exchange for a lower dry packing-factor position.

At 50 and 76 mm, the trade-off reverses:

more area, but higher factor.

This is precisely why final selection has to be model-specific.

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26. Which Is Better for High Contacting-Area Priority?

The answer changes by size.

CMR stronger at:

• 16 mm;
• 25 mm;
• 50 mm;
• 76 mm.

Pall stronger at:

• 38 mm.

But geometric area does not equal guaranteed mass-transfer efficiency.

Effective performance also depends on:

• wetting;
• distribution;
• fluid properties;
• operating loads.

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27. Which Is Better for Lower-Pressure-Drop Screening?

Using dry packing factor only:

Pall Ring has the lower catalog value at:

• 16 mm;
• 25 mm;
• 50 mm;
• 76 mm.

CMR has the lower catalog value at:

• 38 mm.

That makes Pall Ring the stronger lower-factor candidate through most of this particular matched series.

But actual operating pressure drop must still be evaluated separately.

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28. Which Is Better for Fouling?

Both are relatively open plastic random packings, but their geometries differ.

Pall Ring

uses:

• open cylindrical walls;
• inward tabs/openings.

Cascade Mini Ring

uses:

• a shorter, lower-profile element.

Fouling suitability depends on:

• solids;
• crystals;
• sticky deposits;
• biological growth;
• selected size.

Neither should be described as:

• clog-proof;
• self-cleaning.

For severe fouling, larger and more open packing or process changes may be necessary.

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29. Which Is Better for a Weight-Sensitive Tower?

The answer is again size-dependent.

CMR is lighter at:

• 25 mm;
• 38 mm;
• 50 mm;
• 76 mm.

But at 16 mm:

CMR is substantially heavier: 135.6 vs 108 kg/m³.

Therefore:

Cascade Mini Ring is not universally lighter than Pall Ring.

Exact model data matter.

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30. Existing Pall Ring Tower: When Does CMR Deserve Evaluation?

A CMR retrofit may be worth reviewing when:

• additional geometric surface area is useful;
• the selected CMR size has favorable voidage;
• reduced bed weight is valuable;
• there is a defined hydraulic or process objective.

For example, at 76 mm:

73.2 → 90 m²/m³ surface area

while dry weight falls slightly.

But packing factor rises:

94 → 112.3 m⁻¹.

That trade-off must be reviewed.

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31. Existing CMR Tower: When Does Pall Ring Make Sense?

Pall Ring may deserve evaluation when:

• lower packing factor is desirable;
• simpler standardized geometry is preferred;
• existing CMR's extra geometric area is unnecessary;
• Pall Ring procurement/standardization has practical value.

At 50 mm, for example:

143.1 → 127 m⁻¹ packing factor

but area falls:

114.2 → 100 m²/m³.

That is an engineered conversion—not an automatic substitution.

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32. Do Not Treat 25 mm Pall and CMR as Like-for-Like

Both may be described commercially as:

25 mm plastic random packing.

Yet the element geometries differ significantly.

Verified dimensions include approximately:

Pall Ring

25 × 25 × 1.2 mm.

Cascade Mini Ring

25 × 12.5 × 1.2 mm. 

The CMR is much shorter in height.

This changes how pieces:

• orient;
• interlock;
• populate the bed.

Nominal diameter alone does not define equivalence.

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33. Do Not Automatically Keep the Same Packed Height

Changing Pall ↔ CMR changes:

• specific surface area;
• packing factor;
• element population;
• geometry.

Therefore:

same nominal size + same packed height does not guarantee equivalent process performance.

An intentional conversion should review:

• process duty;
• gas load;
• liquid load;
• allowable pressure drop;
• tower ID;
• packed height.

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34. Tower Diameter Must Still Control Size Selection

Before selecting between Pall and CMR, confirm that the proposed size is reasonable relative to:

tower internal diameter.

Large 76 mm packing in a narrow tower can lead to:

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

The better selection sequence is:

Tower ID → Suitable Size Class → Pall vs CMR Geometry

not the reverse.

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35. Polymer Material Is a Separate Decision

Both products can be supplied in suitable plastic materials depending on project requirements and manufacturing availability.

The geometry comparison does not establish whether the correct polymer is:

• PP;
• PVDF;
• CPVC;
• another polymer.

Material compatibility depends on:

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

The correct geometry made from an unsuitable polymer is still an unsuitable packing.

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Decision Table

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Common Selection Mistakes

Assuming Cascade Mini Ring Is Automatically an Upgrade from Pall Ring

The data do not support a universal hierarchy.

Saying CMR Always Has More Surface Area

False at 38 mm.

Saying CMR Always Has Lower Packing Factor

False at 16, 25, 50 and 76 mm in this series.

Saying CMR Is Always Lighter

False at 16 mm.

Using Void Fraction Alone to Predict Packing Factor

The 38 and 50 mm comparisons show why this is unreliable.

Selecting from Nominal Diameter Alone

Pall and CMR element proportions differ strongly.

Converting Packing Factor Directly into Pressure Drop

Actual tower conditions are required.

Assuming More Pieces Means Better Mass Transfer

Element geometry and effective wetting matter more.

Changing Geometry Without Reviewing Packed Height

That is a retrofit, not a simple replacement.

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Frequently Asked Questions

Which has more surface area, Plastic Pall Ring or Plastic Cascade Mini Ring?

It depends on size. CMR has higher verified area at 16, 25, 50 and 76 mm, while Pall Ring has higher area at 38 mm. 

Which has higher void fraction?

The answer also changes by size. At 25 and 38 mm the verified values are equal; Pall is higher at 16 mm; CMR is higher at 50 and 76 mm.

Which has lower dry packing factor?

Pall Ring at 16, 25, 50 and 76 mm; CMR at 38 mm.

What is the 25 mm comparison?

Pall Ring:

• 213 m²/m³;
• 90% void;
• 68 kg/m³;
• 53,500 pcs/m³;
• 285 m⁻¹.

CMR:

• 228 m²/m³;
• 90% void;
• 65 kg/m³;
• 81,500 pcs/m³;
• 312.8 m⁻¹.

What is special about 38 mm?

Both have 91% void fraction, but Pall provides more area while CMR has the lower packing factor.

What is the 50 mm comparison?

Pall:

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

CMR:

• 114.2 m²/m³;
• 92.7% void;
• 43 kg/m³;
• 143.1 m⁻¹.

Which is better for lower pressure drop?

The dry packing-factor ranking favors Pall at most matched sizes in this dataset, but actual operating pressure drop requires tower-specific hydraulic conditions.

Is CMR lighter?

Usually in the 25–76 mm matched examples, but not at 16 mm.

Can CMR directly replace a Pall Ring of the same nominal size?

Do not treat it as like-for-like. Element proportions, surface area, packing population and packing factor can differ materially.

Which should be used in a scrubber?

The answer depends on tower diameter, gas/liquid loads, removal duty, fouling, allowable pressure drop and polymer compatibility.

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Selection Takeaway

Plastic Pall Ring vs Plastic Cascade Mini Ring is one of the clearest examples of why random-packing selection cannot be reduced to “newer geometry is better.”

At 16 mm:

Pall → 320 m²/m³ / 88% void / 108 kg/m³ / 376 m⁻¹

versus:

CMR → 370 m²/m³ / 85% void / 135.6 kg/m³ / 602.6 m⁻¹.

CMR gains area but gives up openness and moves to a much higher packing-factor position.

At 25 mm:

Pall → 213 m²/m³ / 90% void / 68 kg/m³ / 285 m⁻¹

versus:

CMR → 228 m²/m³ / 90% void / 65 kg/m³ / 312.8 m⁻¹.

At 38 mm:

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

versus:

CMR → 132.5 m²/m³ / 91% void / 54 kg/m³ / 175.8 m⁻¹.

Here the relationship reverses: Pall has more area, CMR has lower packing factor.

At 50 mm:

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

versus:

CMR → 114.2 m²/m³ / 92.7% void / 43 kg/m³ / 143.1 m⁻¹.

At 76 mm:

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

versus:

CMR → 90 m²/m³ / 92.9% void / 44 kg/m³ / 112.3 m⁻¹. 

The engineering conclusion is therefore:

CMR often provides more geometric surface area, but this does not automatically produce a lower packing factor. Pall Ring frequently retains the lower dry packing-factor position, while the 38 mm model becomes an important exception where CMR sacrifices area and gains the lower factor.

The correct selection sequence is:

Tower Diameter → Size Class → Required Contacting Area → Hydraulic Constraint → Fouling → Compare Exact Pall / CMR Data → Packed-Bed Weight → Polymer Compatibility → Internals Review

The key principle is:

Do not choose Plastic Cascade Mini Ring because it appears to be a more developed geometry, and do not choose Pall Ring simply because it is conventional. Compare the exact size—the balance between area, voidage and packing factor can reverse from one size to the next.