Ceramic Raschig Ring Size Selection: How to Choose from 6 to 100 mm

Ceramic Raschig Ring size changes the packed bed from an extremely fine, high-surface-area structure to a much coarser industrial bed—but the relationship is not perfectly linear. DAIER's catalog-confirmed series spans approximately 6 to 100 mm, with specific surface area ranging from about 712 to 70 m²/m³ and packing factor ranging from approximately 5,249 to 172 m⁻¹.

The verified product range includes:

• 6 × 6 mm;
• 13 × 13 mm;
• 16 × 16 mm;
• 19 × 19 mm;
• 25 × 25 mm;
• 38 × 38 mm;
• 40 × 40 mm;
• 50 × 50 mm;
• 80 × 80 mm;
• 100 × 100 mm. 

The main selection principle is:

Smaller Ceramic Raschig Ring generally provides greater geometric surface-area density, while larger packing generally creates a coarser bed with fewer elements—but actual void fraction, bulk density and packing factor must be checked from the supplier's specific product data rather than assumed from nominal size alone.

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1. Ceramic Raschig Ring Size Data

DAIER's verified engineering database provides the following product data:

These values immediately show why Ceramic Raschig Ring size should not be selected from diameter alone.

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2. The Overall Size Trend

Across the family, the broad direction is clear.

As nominal size increases:

• geometric surface area generally decreases;
• number of elements per cubic meter falls dramatically;
• the packed bed generally becomes coarser.

For example:

6 mm

Approximately:

• 712 m²/m³;
• more than 3 million pieces/m³.

100 mm

Approximately:

• 70 m²/m³;
• only 1,000 pieces/m³. 

That is an enormous structural change.

A 6 mm bed and a 100 mm bed should therefore not be treated as slightly different versions of the same packing.

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3. Why Specific Surface Area Matters

Specific surface area describes how much geometric packing surface exists within one cubic meter of packed bed.

More geometric area can create more potential surface for:

• liquid wetting;
• gas-liquid contact;
• interfacial mass transfer.

This explains why smaller Raschig Rings may be considered for:

• clean contacting duties;
• smaller columns;
• processes where area density matters strongly.

However:

Geometric surface area is not the same as effective mass-transfer area.

Actual performance also depends on:

• liquid distribution;
• wetting behavior;
• gas flow;
• liquid flow;
• process driving force.

Therefore:

6 mm should not automatically be selected simply because it has 712 m²/m³ of geometric area.

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4. Why Packing Population Matters

The number of elements per cubic meter decreases extremely quickly as size increases.

Examples:

• 6 mm — 3,022,935 pcs/m³;
• 13 mm — 377,867 pcs/m³;
• 25 mm — 52,000 pcs/m³;
• 50 mm — 5,792 pcs/m³;
• 100 mm — 1,000 pcs/m³. 

Packing population affects:

• number of packing-to-packing contacts;
• characteristic flow-path size;
• fouling sensitivity;
• installation behavior.

This is one reason very small ceramic packing should be used cautiously in dirty service.

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5. 6 mm Ceramic Raschig Ring

The 6 × 6 mm model is an extreme fine-packing option.

Its verified data include:

• 712 m²/m³ surface area;
• 62% void fraction;
• 1,050 kg/m³ bulk density;
• more than 3 million pieces/m³;
• 5,249 m⁻¹ packing factor. 

This gives it:

maximum geometric area density

but also:

the finest and heaviest bed in the verified series.

6 mm May Be Considered When

• the process is exceptionally clean;
• the tower is small;
• contact-area density is very important;
• hydraulic load is limited.

Major Boundaries

It deserves strong caution where there is:

• scaling;
• crystallization;
• suspended solids;
• high gas throughput;
• tight pressure-drop allowance.

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6. Why 6 mm Is a Special Engineering Case

The 6 mm model has a packing factor of approximately:

5,249 m⁻¹.

The 13 mm product is already much lower at:

1,903 m⁻¹.

So moving from 6 to 13 mm cuts packing factor dramatically.

At the same time, surface area decreases from:

712 → 367 m²/m³.

This shows that very small Raschig Ring sizes exist in a fundamentally different hydraulic region from standard industrial sizes.

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7. 13 mm Ceramic Raschig Ring

The 13 mm model provides:

• 367 m²/m³ surface area;
• 64% void fraction;
• 800 kg/m³ bulk density;
• 377,867 pcs/m³;
• 1,903 m⁻¹ packing factor. 

It remains a very fine packed bed, but it is much less extreme than 6 mm.

It may deserve consideration when:

• high surface-area density is required;
• service is clean;
• tower diameter favors a relatively small element.

Its low 64% void fraction remains an important hydraulic limitation.

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8. 16 mm Ceramic Raschig Ring

The 16 mm model provides:

• 305 m²/m³ surface area;
• 73% void fraction;
• 800 kg/m³ bulk density;
• 192,500 pcs/m³;
• 900 m⁻¹ packing factor. 

The change from 13 to 16 mm is significant.

Void fraction rises from:

64% → 73%

while packing factor falls from:

1,903 → 900 m⁻¹.

This makes 16 mm a much more open bed than 13 mm while still retaining substantial geometric area.

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9. 19 mm Ceramic Raschig Ring

The 19 mm product provides:

• 243 m²/m³ surface area;
• 72% void fraction;
• 750 kg/m³ bulk density;
• 109,122 pcs/m³;
• 837 m⁻¹ packing factor. 

An important observation appears here:

Void fraction decreases slightly from 73% at 16 mm to 72% at 19 mm.

So even at these smaller sizes:

larger does not automatically mean higher void fraction.

The actual wall geometry matters.

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10. 25 mm Ceramic Raschig Ring

The 25 × 25 mm model provides:

• 190 m²/m³ surface area;
• 74% void fraction;
• 650 kg/m³ bulk density;
• 52,000 pcs/m³;
• 508 m⁻¹ packing factor. 

This size moves the product firmly away from the extremely fine small-ring region.

It may be considered where engineers want:

• substantial geometric area;
• more practical hydraulic openness;
• lower ceramic bed weight than the very small sizes.

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11. 38 mm Ceramic Raschig Ring

The 38 mm model provides:

• 121 m²/m³ surface area;
• 73% void fraction;
• 650 kg/m³ bulk density;
• 13,667 pcs/m³;
• 312 m⁻¹ packing factor. 

Compared with 25 mm:

• surface area drops substantially;
• packing population falls dramatically;
• packing factor falls from 508 to 312 m⁻¹.

This places 38 mm toward a more hydraulically open industrial position.

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12. Why 38 mm and 40 mm Are Particularly Interesting

One of the most useful observations in DAIER's verified data is that 40 mm does not simply continue the expected monotonic trend from 38 mm.

38 mm

• surface area: 121 m²/m³;
• void fraction: 73%;
• packing factor: 312 m⁻¹.

40 mm

• surface area: 126 m²/m³;
• void fraction: 75%;
• packing factor: 350 m⁻¹. 

Despite being slightly larger, the 40 mm product has:

• slightly higher surface area;
• higher void fraction;
• also higher packing factor.

This means:

38 mm and 40 mm should be treated as different supplier-specific geometries—not as mathematically interchangeable sizes.

That is exactly the kind of detail generic size guides often miss.

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13. 50 mm Ceramic Raschig Ring

The 50 mm model provides:

• 92 m²/m³ surface area;
• 74% void fraction;
• 600 kg/m³ bulk density;
• 5,792 pcs/m³;
• 213 m⁻¹ packing factor. 

This makes 50 mm one of the strongest candidates when the project begins to prioritize:

• larger characteristic passages;
• lower packing factor;
• reduced packing population.

It may be relevant in:

• larger scrubbers;
• absorbers;
• moderate fouling conditions

where very small rings would create an unnecessarily fine bed.

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14. 80 mm Ceramic Raschig Ring

The 80 mm model has an unusual parameter combination:

• 46 m²/m³ surface area;
• 80% void fraction;
• 660 kg/m³ bulk density;
• 1,953 pcs/m³;
• 280 m⁻¹ packing factor. 

It has the highest verified void fraction in the series:

80%.

But notice something important:

Its packing factor of 280 m⁻¹ is actually higher than the 213 m⁻¹ of the 50 mm product.

Therefore:

80 mm cannot automatically be described as hydraulically less restrictive than 50 mm simply because it is larger and has higher voidage.

The real packing geometry must be considered.

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15. Why 80 mm Is a Perfect Example of “Do Not Assume”

A generic article might say:

larger packing → higher voidage → lower packing factor.

DAIER's catalog data show why that is unsafe.

Moving:

50 mm → 80 mm

changes:

• surface area: 92 → 46 m²/m³;
• void fraction: 74 → 80%;
• packing factor: 213 → 280 m⁻¹;
• bulk density: 600 → 660 kg/m³. 

So 80 mm is:

• more open by void fraction;
• but heavier;
• and has a higher published packing factor.

This should trigger a real hydraulic review instead of a simple size rule.

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16. 100 mm Ceramic Raschig Ring

The 100 × 100 mm product provides:

• 70 m²/m³ surface area;
• 70% void fraction;
• 600 kg/m³ bulk density;
• 1,000 pcs/m³;
• 172 m⁻¹ packing factor. 

This creates another non-monotonic point.

Compared with 80 mm:

Surface area rises

46 → 70 m²/m³.

Void fraction falls

80% → 70%.

Packing factor falls

280 → 172 m⁻¹.

Therefore:

80 and 100 mm should not be ranked using diameter alone.

They are distinct catalog geometries.

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17. Surface Area Does Not Always Decrease Smoothly

The broad trend is downward, but local exceptions exist.

For example:

• 38 mm — 121 m²/m³;
• 40 mm — 126 m²/m³.

And:

• 80 mm — 46 m²/m³;
• 100 mm — 70 m²/m³. 

This demonstrates a crucial procurement principle:

Nominal size is not enough to reconstruct physical packing properties.

Supplier geometry and wall dimensions matter.

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18. Void Fraction Does Not Increase Smoothly Either

The verified series contains:

• 13 mm — 64%;
• 16 mm — 73%;
• 19 mm — 72%;
• 25 mm — 74%;
• 38 mm — 73%;
• 40 mm — 75%;
• 50 mm — 74%;
• 80 mm — 80%;
• 100 mm — 70%. 

There is no simple monotonic line.

Therefore:

Never publish “void fraction increases as Ceramic Raschig Ring size increases” as a universal rule.

A safer statement is:

Larger sizes generally create a coarser bed, but actual void fraction must be confirmed from the exact product specification.

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19. Packing Factor Is Also Non-Monotonic

The same warning applies to packing factor.

Examples:

• 38 mm — 312 m⁻¹;
• 40 mm — 350 m⁻¹;
• 50 mm — 213 m⁻¹;
• 80 mm — 280 m⁻¹;
• 100 mm — 172 m⁻¹. 

Therefore:

larger size does not guarantee a lower published packing factor at every adjacent step.

This is one of the strongest reasons to build a supplier-specific engineering database.

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20. Size Selection for Clean Contacting Service

For relatively clean gas-liquid service, smaller sizes may deserve stronger consideration when:

• contacting-area density is important;
• hydraulic load is manageable;
• fouling is low.

Possible preliminary regions:

6–19 mm

Very high-area, fine-bed service.

25–40 mm

More balanced industrial contacting.

50 mm and above

Coarser-bed operation where openness and fouling tolerance receive greater attention.

This is a preliminary framework rather than a guaranteed size assignment.

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21. Size Selection for High Gas Throughput

High gas flow increases the importance of:

• open flow pathways;
• manageable hydraulic resistance.

It may move the preliminary decision away from very small:

• 6;
• 13;
• 16 mm

packing.

However, because packing factor is non-monotonic in the larger series, engineers should not simply jump to the largest available size.

For example:

50 mm has a lower published packing factor than 80 mm.

Actual tower hydraulics should decide.

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22. Size Selection for Fouling Service

Fouling generally moves the engineer away from extremely fine packing.

Compare packing population:

• 6 mm — over 3 million pcs/m³;
• 25 mm — 52,000 pcs/m³;
• 50 mm — 5,792 pcs/m³;
• 100 mm — 1,000 pcs/m³. 

Fewer and larger elements generally create a coarser bed.

This can make larger sizes more attractive when:

• scaling;
• deposits;
• suspended solids

are present.

But severe fouling may require another packing geometry rather than simply a larger Raschig Ring.

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23. Crystallization Can Eliminate Very Small Sizes

Crystallizing service creates deposits on:

• inner ring walls;
• outer surfaces;
• packing contact points.

A bed containing millions of tiny elements provides many locations where deposits can bridge flow paths.

Therefore:

6–16 mm Ceramic Raschig Ring should be approached cautiously where crystallization is significant.

The correct selection may move toward:

• larger packing;
• more open geometry;
• a different tower strategy.

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24. Tower Diameter Must Match Packing Size

Large Ceramic Raschig Rings require sufficient tower diameter.

If 80 or 100 mm packing is installed in a small column:

• too few elements span the cross-section;
• wall effects become significant;
• bed randomness can deteriorate.

Conversely, choosing 6 mm packing in a very large tower may create an unnecessarily fine and heavy bed.

Therefore size should always be evaluated against:

Tower Internal Diameter.

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25. Ceramic Bed Weight Matters

Ceramic packing is relatively heavy.

The verified bulk densities range from approximately:

• 1,050 kg/m³ for 6 mm;
• 800 kg/m³ for 13–16 mm;
• 600–660 kg/m³ for many larger sizes. 

This affects:

• packing support design;
• tower structural load;
• installation;
• shipping weight.

A size change can therefore be both a:

hydraulic modification

and a:

mechanical modification.

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26. Why 80 mm Is Heavier Than 50 mm in the Verified Data

Another useful non-linear result:

50 mm

Bulk density:

600 kg/m³

80 mm

Bulk density:

660 kg/m³.

Larger does not automatically mean a lighter bed.

Wall thickness and element geometry can offset the reduction in packing count.

Structural calculations should therefore use actual catalog data.

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27. Replacement Projects Need Exact Size Identification

For an existing Ceramic Raschig Ring tower, identify:

• actual ring OD;
• ring height;
• wall thickness;
• ceramic material;
• bed height;
• tower ID.

Do not assume an existing:

“about 40 mm Raschig Ring”

can be replaced blindly with either 38 or 40 mm.

The verified data show those two sizes have different:

• surface area;
• void fraction;
• packing factor. 

Exact product identification matters.

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28. Size Changes Are Engineering Retrofits

Changing:

25 mm → 50 mm

changes surface area from:

190 → 92 m²/m³

and packing factor from:

508 → 213 m⁻¹.

That is not a like-for-like replacement.

Likewise:

50 mm → 80 mm

does not simply provide “lower pressure drop,” because the published packing factor actually increases.

Any major size change should therefore be reviewed for both:

• mass transfer;
• hydraulics.

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29. Support Grid Compatibility

The support grid must:

• retain the selected ring;
• support the ceramic bed weight;
• provide sufficient gas and liquid open area.

Changing from:

100 mm → 25 mm

may make the existing support openings too large.

Changing toward heavier small ceramic packing can also increase structural load.

Packing support should therefore be reviewed before ordering a substantially different size.

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30. Ceramic Material Quality Still Matters

Size is not the only ceramic packing specification.

Final procurement may also need to verify material characteristics such as:

• ceramic composition;
• acid resistance;
• alkali resistance;
• mechanical strength.

A 50 mm Ceramic Raschig Ring test report, for example, may be relevant for material acceptance—but material-test results should not automatically be generalized to every ceramic grade or every supplier.

The size decision and material-quality decision should remain separate.

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Ceramic Raschig Ring Size Decision Table

This is a preliminary interpretation of DAIER's verified product data, not a guaranteed tower-performance ranking.

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31. Quick Selection Logic

Move toward 6–19 mm when:

• service is exceptionally clean;
• high geometric contacting area is essential;
• hydraulic load is limited.

Move toward 25 mm when:

• strong contact area is still important;
• a more industrial bed is desired.

Move toward 38–40 mm when:

• contact and hydraulics need a more balanced position;
• exact supplier data can be confirmed.

Move toward 50 mm when:

• a significantly coarser bed is desired;
• moderate fouling or higher throughput matters.

Move toward 80–100 mm only after:

• tower diameter is confirmed;
• actual packing factor is reviewed;
• required mass transfer is checked.

Do not select those sizes from diameter alone.

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32. What Information Should Be Included in an RFQ?

Provide:

• required or existing packing size;
• tower internal diameter;
• packed-bed height;
• gas composition;
• liquid composition;
• gas flow;
• liquid flow;
• operating temperature;
• operating pressure;
• process duty;
• allowable pressure drop;
• fouling or crystallization conditions.

For replacement projects also provide:

• existing ring dimensions;
• wall thickness if available;
• support-grid opening;
• photos or drawings;
• reason for replacement.

Ask the supplier to confirm:

• actual dimensions;
• surface area;
• void fraction;
• bulk density;
• pieces per cubic meter;
• packing factor;
• ceramic material specification.

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Common Selection Mistakes

Choosing 6 mm Because It Has 712 m²/m³ Surface Area

It also has approximately 5,249 m⁻¹ packing factor and more than 3 million pieces/m³.

Assuming Larger Always Means Higher Void Fraction

The verified series clearly disproves this.

Assuming Larger Always Means Lower Packing Factor

40 mm exceeds 38 mm, and 80 mm exceeds 50 mm in the published data.

Treating 38 and 40 mm as Equivalent

Their verified physical properties differ.

Assuming 80 mm Is Automatically Better Than 50 mm for Hydraulics

Its void fraction is higher, but published packing factor is also higher.

Ignoring Ceramic Bed Weight

Bulk density remains substantial across the range.

Changing Size Without Checking the Support Grid

Smaller replacement rings may not be retained.

Assuming Bed Height Can Stay Unchanged

Size changes affect both geometric area and hydraulics.

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Frequently Asked Questions

What Ceramic Raschig Ring sizes does DAIER's verified catalog contain?

The catalog-aligned series includes approximately 6, 13, 16, 19, 25, 38, 40, 50, 80 and 100 mm.

Which size has the highest specific surface area?

The 6 mm model, at approximately 712 m²/m³.

Which size has the lowest packing factor?

The 100 mm model in the verified dataset, at approximately 172 m⁻¹.

Which size has the highest void fraction?

The 80 mm model, at approximately 80%.

What is the surface area of 25 mm Ceramic Raschig Ring?

Approximately 190 m²/m³.

What is the surface area of 50 mm Ceramic Raschig Ring?

Approximately 92 m²/m³.

Are 38 mm and 40 mm Ceramic Raschig Rings equivalent?

No. DAIER's verified data show different surface area, void fraction, packing count and packing factor.

Is 80 mm automatically lower pressure drop than 50 mm?

No. The verified 80 mm product has higher void fraction but also a higher published packing factor than the 50 mm product, so actual hydraulic conditions must be evaluated.

Is smaller Ceramic Raschig Ring always better for mass transfer?

No. Smaller packing provides greater geometric area but can create a much finer, heavier and more fouling-sensitive bed.

Can I replace 38 mm packing with 40 mm directly?

Do not assume they are identical. Confirm dimensions, supplier data, tower hydraulics and existing internals first.

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Selection Takeaway

Ceramic Raschig Ring size selection cannot be reduced to “smaller means more efficient and larger means lower pressure drop.”

The broad trend is real:

6 mm → very high surface area / millions of elements / extremely high packing factor

while:

100 mm → coarse bed / only about 1,000 elements/m³ / much lower packing factor.

But DAIER's catalog-confirmed data also reveal important non-linear behavior:

• 40 mm has higher surface area and packing factor than 38 mm;
• 80 mm has higher void fraction but also higher packing factor than 50 mm;
• 100 mm has more surface area than 80 mm but much lower void fraction. 

This means the correct selection process is:

Process Duty → Gas/Liquid Loads → Fouling → Required Contacting Area → Exact Supplier Product Data → Tower Diameter → Ceramic Bed Weight → Packing Size → Support Grid Review

The key principle is:

Select Ceramic Raschig Ring from the actual supplier-specific physical data and process requirements—not from nominal diameter trends alone.