Metal Pall Ring vs Metal Conjugated Ring: Which Random Packing Should You Select?

Metal Pall Ring and Metal Conjugated Ring are both open metal random packings, but DAIER's directly comparable 25, 38 and 50 mm data place them in consistently different engineering positions. Metal Pall Ring provides higher specific surface area and higher void fraction at every matched size, while Metal Conjugated Ring provides substantially lower dry bulk density and lower dry packing factor.

The central selection question is therefore:

Does the tower benefit more from the higher geometric area and free volume of Metal Pall Ring, or from the much lighter and lower-packing-factor bed created by Metal Conjugated Ring?

Neither packing is universally superior.

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1. Direct Answer

Choose Metal Pall Ring more readily when:

• higher geometric surface area is important;
• high verified void fraction is attractive;
• Pall Ring is already proven in the existing tower;
• like-for-like replacement minimizes project risk;
• the additional dry bed weight is acceptable.

Evaluate Metal Conjugated Ring more strongly when:

• low packed-bed weight is important;
• lower dry packing factor is desirable;
• tower-support loading is constrained;
• a retrofit needs to reduce dead load;
• the selected size provides sufficient geometric contacting area.

The core trade-off in the directly matched sizes is:

Metal Pall Ring → More Surface Area + More Void Fraction

versus:

Metal Conjugated Ring → Lower Bed Weight + Lower Packing Factor

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2. Direct Same-Size Comparison

DAIER's catalog-aligned product database provides exact comparisons at:

• 25 mm;
• 38 mm;
• 50 mm. 

The pattern is unusually consistent.

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3. Pall Ring Has Higher Surface Area at Every Exact Matched Size

25 mm

Pall Ring:

212 m²/m³

Conjugated Ring:

185 m²/m³

38 mm

145 vs 116 m²/m³

50 mm

106 vs 86 m²/m³.

So within these matched models:

Metal Pall Ring consistently occupies the stronger geometric contact-area position.

This can matter when the tower requires substantial potential wetted area.

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4. How Large Is the Surface-Area Difference?

The Pall Ring advantage is approximately:

25 mm

27 m²/m³

38 mm

29 m²/m³

50 mm

20 m²/m³.

Relative to the Conjugated Ring values, these are meaningful differences.

But:

specific surface area is geometric—not guaranteed effective mass-transfer area.

Actual process performance also depends on:

• liquid wetting;
• distributor quality;
• vapor/gas loading;
• liquid loading;
• fluid properties.

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5. Pall Ring Also Has Higher Void Fraction at Every Matched Size

 

This is important because Pall Ring does not achieve its higher surface area by sacrificing catalog free volume in these three comparisons.

Instead, it simultaneously provides:

• more area;
• more void fraction.

At first glance that makes Pall Ring appear dominant.

But the weight and packing-factor data change the picture.

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6. Conjugated Ring Is Much Lighter

Bulk density comparison:

25 mm

Pall Ring:

288 kg/m³

Conjugated Ring:

216 kg/m³

38 mm

246 vs 131 kg/m³

50 mm

185 vs 97 kg/m³.

The dry-weight advantage becomes especially large at 38 and 50 mm.

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7. The 50 mm Weight Difference Is Nearly Twofold

At 50 mm:

Metal Pall Ring

185 kg/m³.

Metal Conjugated Ring

97 kg/m³.

Difference:

88 kg/m³.

For a 30 m³ packed bed:

Pall Ring

30 × 185 = 5,550 kg

Conjugated Ring

30 × 97 = 2,910 kg

Difference:

approximately 2.64 tonnes of dry packing.

This can materially affect:

• packing support load;
• support beams;
• retrofit feasibility;
• shipping weight.

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8. Why Dry Bed Weight Can Decide a Retrofit

In a new tower, support structure can be designed around the selected packing.

In an existing tower, however, the structure already exists.

If the vessel has:

• limited support margin;
• aged internals;
• weight-sensitive design;

a large reduction in dry packing weight can be very valuable.

Therefore:

Conjugated Ring can become attractive even when Pall Ring has better area and voidage numbers.

Mechanical constraints can outweigh purely geometric advantages.

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9. Operating Load Is More Than Dry Packing Weight

Bulk density only represents dry packing mass.

The support structure may also carry:

• liquid holdup;
• fouling deposits;
• support-grid weight;
• dynamic operating loads.

Therefore the simple calculations above are useful for screening only.

Final structural review must use:

the complete operating load case.

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10. Conjugated Ring Has Lower Packing Factor at Every Exact Size

 

So across all directly matched models:

Conjugated Ring occupies the lower dry-packing-factor position.

The advantage becomes particularly strong at 50 mm.

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11. What Does the 50 mm Packing-Factor Difference Mean?

Pall Ring

128.5 m⁻¹.

Conjugated Ring

97 m⁻¹.

This makes Conjugated Ring a strong candidate where hydraulic resistance is an important screening constraint.

But:

97 vs 128.5 m⁻¹ does not mean actual tower pressure drop will be lower by the same percentage.

Real ΔP depends on operating conditions.

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12. Packing Factor Is Not Actual Pressure Drop

Actual pressure drop depends on:

• gas or vapor velocity;
• liquid flow;
• fluid density;
• viscosity;
• tower diameter;
• packed height.

Packing factor helps characterize packing geometry for hydraulic evaluation.

It should not be converted directly into:

• guaranteed ΔP;
• guaranteed capacity.

The correct statement is:

Conjugated Ring's lower packing factor makes it a stronger candidate for hydraulic evaluation where pressure-drop margin matters.

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13. 25 mm Is the Closest Comparison

At 25 mm:

Metal Pall Ring

• 212 m²/m³;
• 96.2% void;
• 288 kg/m³;
• 53,500 pcs/m³;
• 229.8 m⁻¹.

Metal Conjugated Ring

• 185 m²/m³;
• 95% void;
• 216 kg/m³;
• 75,000 pcs/m³;
• 216 m⁻¹. 

The differences in:

• void fraction;
• packing factor

are relatively modest.

The most noticeable differences are:

• Pall Ring provides more surface area;
• Conjugated Ring is lighter.

So 25 mm is a relatively balanced trade-off.

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14. More Pieces Do Not Mean More Surface Area

At 25 mm:

Conjugated Ring

75,000 pcs/m³.

Pall Ring

53,500 pcs/m³.

Conjugated Ring contains about:

40% more individual elements

but still provides less geometric surface area:

185 vs 212 m²/m³.

This demonstrates:

Packing population cannot be used as a substitute for specific surface area.

The geometry of each element matters.

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15. 38 mm Makes the Mechanical Difference Much Larger

At 38 mm:

Pall Ring

• 145 m²/m³;
• 96.7% void;
• 246 kg/m³;
• 15,180 pcs/m³;
• 151.7 m⁻¹.

Conjugated Ring

• 116 m²/m³;
• 96% void;
• 131 kg/m³;
• 19,500 pcs/m³;
• 131 m⁻¹.

Pall Ring remains stronger in:

• surface area;
• void fraction.

But Conjugated Ring is approximately:

115 kg/m³ lighter.

That is a substantial mechanical advantage.

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16. Why 38 mm Is a Strong Retrofit Decision Point

For a 20 m³ bed:

Pall Ring dry weight

approximately:

4,920 kg

Conjugated Ring

approximately:

2,620 kg

Difference:

about 2.3 tonnes.

At the same time, surface area changes:

145 → 116 m²/m³.

So the retrofit question becomes:

Can the process tolerate less geometric area in exchange for a much lighter and lower-packing-factor bed?

That is a real engineering decision.

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17. 50 mm Makes the Trade-Off Clearest

At 50 mm:

Pall Ring

• 106 m²/m³;
• 97.5% void;
• 185 kg/m³;
• 6,500 pcs/m³;
• 128.5 m⁻¹.

Conjugated Ring

• 86 m²/m³;
• 96% void;
• 97 kg/m³;
• 9,772 pcs/m³;
• 97 m⁻¹. 

This creates a very clear split.

Pall Ring favors:

• geometric area;
• free volume.

Conjugated Ring favors:

• low bed weight;
• lower packing factor.

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18. Higher Void Fraction Does Not Automatically Mean Lower Packing Factor

The 50 mm comparison proves this.

Pall Ring has:

97.5% void

versus:

96%

for Conjugated Ring.

Yet Pall Ring also has the higher packing factor:

128.5 vs 97 m⁻¹.

This is an important engineering lesson:

Void fraction and packing factor describe different geometric characteristics.

Do not use one parameter as a substitute for the other.

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19. Why Can That Happen?

Void fraction tells us:

how much total bed volume is open rather than solid.

Packing factor reflects other geometric features relevant to hydraulic correlations.

Two packing types can therefore have different combinations of:

• open volume;
• surface orientation;
• internal passages;
• element shape.

So:

higher voidage does not guarantee a lower packing factor.

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20. Which Is Better for High Gas or Vapor Throughput?

The answer requires hydraulic evaluation.

Pall Ring provides:

• higher verified void fraction.

Conjugated Ring provides:

• lower dry packing factor.

These two descriptors point in different directions.

Therefore the defensible selection approach is:

compare the exact models using the actual gas/vapor and liquid loads.

Do not choose from a single catalog number.

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21. Which Is Better for High Geometric Contacting Area?

Metal Pall Ring has the stronger position in the directly matched series.

At:

• 25 mm;
• 38 mm;
• 50 mm,

its surface area is consistently higher.

Therefore Pall Ring deserves stronger screening where:

• geometric area is important;
• bed weight is acceptable;
• proven Pall Ring operation is valuable.

But actual effective mass transfer still depends on process conditions.

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

Metal Conjugated Ring has the stronger position.

The difference becomes especially large at:

• 38 mm;
• 50 mm.

This can matter in:

• existing-tower revamps;
• older vessels;
• support-limited installations;
• weight-sensitive equipment.

A lower bed weight can sometimes avoid:

• major support modification;
• beam reinforcement.

That can be economically significant.

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23. Which Is Better for Fouling?

There is no universal answer.

Factors include:

• opening geometry;
• element contact points;
• packing size;
• deposit type;
• solids concentration.

Conjugated Ring has:

• lower packing factor at matched sizes.

Pall Ring has:

• higher verified void fraction.

Neither should be described as:

• clog-proof;
• self-cleaning.

For severe fouling, another packing family or process change may be required.

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24. Existing Pall Ring Tower: When Does Conjugated Ring Become Interesting?

A Conjugated Ring retrofit may deserve evaluation when the existing tower has a defined problem such as:

• excessive structural load;
• support-grid limitations;
• hydraulic pressure-drop concerns;
• need to reduce dry bed mass.

For example, at 50 mm:

185 → 97 kg/m³

is a very large dry-load reduction.

But the project also changes:

106 → 86 m²/m³ surface area.

So process duty must be checked.

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25. Do Not Convert a Successful Pall Ring Tower Without a Reason

If the existing Pall Ring tower:

• meets required removal or separation;
• has acceptable pressure drop;
• has adequate structural support;
• operates reliably;

there may be no reason to change.

Like-for-like replacement preserves:

• known performance;
• known hydraulic behavior;
• lower engineering uncertainty.

A lower alternative packing factor alone is not sufficient justification for conversion.

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26. Existing Conjugated Ring Tower: When Might Pall Ring Be Considered?

Pall Ring may deserve evaluation when:

• additional geometric surface area is needed;
• process duty has increased;
• higher void fraction is attractive;
• additional bed weight is structurally acceptable.

For example, at 38 mm:

116 → 145 m²/m³

adds significant geometric area.

But dry bulk density also changes:

131 → 246 kg/m³.

That is a major structural penalty.

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27. Same Nominal Size Is Not Like-for-Like Replacement

At 50 mm, both products are sold as:

50 mm metal random packing.

Yet their catalog properties differ in every major field:

• surface area;
• void fraction;
• bulk density;
• packing population;
• packing factor.

Therefore:

same nominal diameter does not mean equivalent packed-bed performance.

A geometry change is a retrofit.

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28. Do Not Automatically Keep the Same Packed Height

Changing packing family changes:

• geometric area;
• wetting behavior;
• hydraulic geometry.

Therefore:

same size + same packed height does not guarantee equivalent mass-transfer performance.

A Pall ↔ Conjugated retrofit should review:

• required duty;
• operating loads;
• packed height.

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29. Large-Size Near Comparison Adds Another Lesson

The closest larger models are:

Metal Pall Ring 76 mm

• 69 m²/m³;
• 97.4% void;
• 265 kg/m³;
• 1,920 pcs/m³;
• 79.6 m⁻¹.

Metal Conjugated Ring 80 mm

• 81 m²/m³;
• 95% void;
• 94.5 kg/m³;
• 3,980 pcs/m³;
• 95 m⁻¹. 

These are near-size-class, not exact same-size products.

Interestingly, the previous pattern changes.

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30. At the Large Size, Conjugated Ring Has More Surface Area

The near-size comparison gives:

Pall Ring 76 mm

69 m²/m³.

Conjugated Ring 80 mm

81 m²/m³.

So unlike the exact 25–50 mm comparisons:

the large Conjugated model provides the higher geometric surface area.

This proves that the small/mid-size family relationship should not be extrapolated indefinitely.

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31. But Large Pall Ring Has Higher Void Fraction and Lower Packing Factor

The same near-size comparison shows:

Pall Ring

• 97.4% void;
• 79.6 m⁻¹.

Conjugated Ring

• 95% void;
• 95 m⁻¹.

So at this larger size class, Pall Ring has:

• higher void fraction;
• lower dry packing factor.

The ranking has partially reversed.

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32. Conjugated Ring Remains Dramatically Lighter

Even at this large size:

Pall Ring

265 kg/m³.

Conjugated Ring

94.5 kg/m³.

The Conjugated Ring remains much lighter.

Therefore:

low packed-bed weight is one of the most persistent engineering characteristics separating these two families.

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33. Why Large-Size Comparisons Must Be Labeled Carefully

76 mm and 80 mm are not identical sizes.

Therefore this comparison should be used for:

engineering positioning

rather than claiming an exact same-size advantage.

Final selection should use:

• the exact commercially proposed model;
• actual tower diameter;
• process loads.

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34. Tower Diameter Must Be Considered

Packing size should be reasonable relative to tower internal diameter.

Large 76–80 mm random packing can create stronger wall effects if the tower is too narrow.

Therefore:

Tower ID → Appropriate Size Class → Packing Geometry

is a better selection sequence than choosing the product family first.

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35. Metal Grade Is a Separate Decision

Both are metal random packings.

But geometry does not tell you whether the correct alloy is:

• SS304;
• SS316L;
• another alloy.

Material selection must consider:

• exact chemical composition;
• concentration;
• operating temperature;
• corrosion mechanism.

A hydraulically suitable packing made from the wrong alloy is still the wrong product.

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36. Thickness Should Be Confirmed in Procurement

Metal packing weight depends strongly on:

• sheet thickness;
• element construction.

For example, the matched product families use different formed geometries and thicknesses.

Therefore an RFQ should request:

• nominal size;
• exact dimensions;
• thickness;
• alloy.

Do not compare only:

USD/m³

without checking whether the products contain comparable metal construction.

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37. Support Grid Review Is Important in Both Directions

Pall → Conjugated

Dry load may fall significantly.

But support-grid retention and geometry still need confirmation.

Conjugated → Pall

Dry load can increase substantially.

Then structural capacity becomes even more important.

Always check:

• support-grid opening;
• support strength;
• support beams;
• hold-down arrangement where relevant.

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Decision Table

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38. Quick Selection Guide

Favor Metal Pall Ring when:

• higher surface area is valuable;
• high void fraction matters;
• existing Pall Ring performance is proven;
• support load is not a major constraint.

Evaluate Metal Conjugated Ring strongly when:

• dry packed-bed weight must be reduced;
• lower packing factor is attractive;
• 38–50 mm size classes are being considered;
• structural retrofit cost matters.

For large 76–80 mm models:

Do not carry the 25–50 mm ranking forward automatically.

Compare the exact proposed data again.

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Common Selection Mistakes

Assuming Pall Ring Is Better Because It Has More Area and Voidage

Conjugated Ring can be dramatically lighter and lower in packing factor.

Assuming Conjugated Ring Always Has Less Surface Area

The large 80 mm model does not follow the 25–50 mm pattern.

Assuming Higher Voidage Means Lower Packing Factor

The matched Pall Ring data show the opposite ranking.

Assuming More Pieces Means More Surface Area

Conjugated Ring contains more pieces at matched sizes but less surface area.

Comparing Only Packing Price per Cubic Meter

Metal thickness and kg/m³ matter.

Treating Same Nominal Size as Equivalent Packing

Every major physical property can differ.

Converting Packing Factor Directly into Pressure Drop

Operating conditions are required.

Ignoring Structural Load in Retrofit Projects

The bed-weight difference can reach several tonnes.

Keeping the Same Bed Height Without Review

Geometry conversion can alter process performance.

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Frequently Asked Questions

Which has more surface area, Metal Pall Ring or Metal Conjugated Ring?

At directly matched 25, 38 and 50 mm sizes, Metal Pall Ring has higher verified specific surface area.

Which has higher void fraction?

Metal Pall Ring also has higher void fraction at all three exact matched sizes.

Which is lighter?

Metal Conjugated Ring is substantially lighter at all three matched sizes.

Which has lower dry packing factor?

Metal Conjugated Ring at 25, 38 and 50 mm.

What is the 25 mm comparison?

Metal Pall Ring:

• 212 m²/m³;
• 96.2% void;
• 288 kg/m³;
• 229.8 m⁻¹.

Metal Conjugated Ring:

• 185 m²/m³;
• 95% void;
• 216 kg/m³;
• 216 m⁻¹.

What is the 38 mm comparison?

Pall Ring:

• 145 m²/m³;
• 96.7% void;
• 246 kg/m³;
• 151.7 m⁻¹.

Conjugated Ring:

• 116 m²/m³;
• 96% void;
• 131 kg/m³;
• 131 m⁻¹.

What is the 50 mm comparison?

Pall Ring:

• 106 m²/m³;
• 97.5% void;
• 185 kg/m³;
• 128.5 m⁻¹.

Conjugated Ring:

• 86 m²/m³;
• 96% void;
• 97 kg/m³;
• 97 m⁻¹.

Does Conjugated Ring always have lower pressure drop?

Its dry packing factor is lower in the directly matched data, but actual operating pressure drop still requires gas and liquid operating conditions.

Which is better for a weight-sensitive retrofit?

Metal Conjugated Ring deserves stronger evaluation because its verified bulk density is much lower.

Can one directly replace the other at the same size?

Do not treat them as like-for-like. Geometry, surface area, voidage, bed weight, packing population and packing factor all change.

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Selection Takeaway

Metal Pall Ring vs Metal Conjugated Ring creates a very clear engineering trade-off in the directly matched 25–50 mm range.

At 25 mm:

Pall Ring → 212 m²/m³ / 96.2% void / 288 kg/m³ / 229.8 m⁻¹

versus:

Conjugated Ring → 185 m²/m³ / 95% void / 216 kg/m³ / 216 m⁻¹.

At 38 mm:

Pall Ring → 145 m²/m³ / 96.7% void / 246 kg/m³ / 151.7 m⁻¹

versus:

Conjugated Ring → 116 m²/m³ / 96% void / 131 kg/m³ / 131 m⁻¹.

At 50 mm:

Pall Ring → 106 m²/m³ / 97.5% void / 185 kg/m³ / 128.5 m⁻¹

versus:

Conjugated Ring → 86 m²/m³ / 96% void / 97 kg/m³ / 97 m⁻¹.

The directly matched data therefore show:

Pall Ring → higher geometric surface area and higher free volume

while:

Conjugated Ring → much lighter bed and lower dry packing factor.

That creates a practical selection sequence:

Process Duty → Required Contacting Area → Hydraulic Constraint → Structural Load → Tower Diameter → Size Class → Alloy → Exact Packing Model → Internals Review

The key principle is:

Do not rank these metal random packings by one “performance” number. Pall Ring and Conjugated Ring solve different constraints, and the correct choice depends on whether the tower is limited more by contacting requirements or by hydraulic/mechanical load.