PTFE Pall Ring Packing: 25 vs 38 vs 50 mm Selection, Material Advantages and Limits

PTFE Pall Ring is a fluoropolymer random packing that combines the open-wall geometry of a Pall Ring with the chemical-resistance characteristics of PTFE. It is mainly considered when ordinary plastic Pall Rings do not provide sufficient material compatibility or temperature margin, while the process still benefits from the more open flow structure of Pall Ring geometry.

DAIER's engineering database currently contains:

• 25 mm PTFE Pall Ring;
• 38 mm PTFE Pall Ring;
• 50 mm PTFE Pall Ring. 

The main selection question is:

Does the process genuinely require PTFE, and if it does, should the tower use 25, 38 or 50 mm Pall Rings to balance mass transfer, hydraulic openness and fouling tolerance?

PTFE should not be specified simply because it is considered a premium polymer.

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1. What Is PTFE Pall Ring Packing?

PTFE Pall Ring belongs to the plastic random packing family.

Each element uses an open ring geometry containing:

• a cylindrical body;
• side-wall openings;
• internal formed surfaces;
• multiple gas and liquid pathways.

Individual rings are randomly loaded into the tower.

Compared with a simple Raschig Ring, Pall Ring geometry allows fluids to pass:

• through the center;
• through side openings;
• around neighboring rings.

This gives the packing a more interconnected bed structure.

The product combines two independent engineering decisions:

Pall Ring Geometry

and

PTFE Material

Both must be justified.

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2. Why Use PTFE for Pall Rings?

Most packed towers do not automatically require PTFE.

Conventional plastic Pall Rings may be produced from materials such as:

• PP;
• PE;
• PVC;
• CPVC;
• PVDF.

These materials may provide adequate performance at substantially lower material cost.

PTFE moves higher on the candidate list when the process involves:

• more demanding chemical compatibility;
• aggressive mixed chemical streams;
• solvent exposure;
• higher operating temperature;
• service where common polymers provide insufficient margin.

Therefore:

PTFE is primarily a material-solution decision—not an automatic mass-transfer upgrade.

Changing PP Pall Rings to PTFE Pall Rings does not by itself guarantee greater tower efficiency.

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3. PTFE Pall Ring vs PTFE Raschig Ring

This is the most important structural boundary after S130.

Both can use PTFE, but their geometry differs substantially.

PTFE Raschig Ring

Uses:

• simple cylindrical wall;
• open central bore;
• minimal internal geometry.

Advantages may include:

• simplicity;
• easier product definition;
• fewer complicated internal features.

PTFE Pall Ring

Adds:

• side-wall openings;
• internal contacting surfaces;
• more multidirectional flow paths.

This can make Pall Ring more attractive when engineers need:

• better internal volume utilization;
• more open side flow;
• additional contacting surfaces.

So the selection becomes:

PTFE Raschig Ring → simpler geometry

versus

PTFE Pall Ring → more open and internally structured geometry

Neither is universally superior.

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4. Verified DAIER Size Range

DAIER's current Engineering Assistant lists PTFE Pall Rings in three principal sizes:

 

The current database also treats these three models as separate engineering-selection nodes rather than one interchangeable product.

That is important because:

25, 38 and 50 mm Pall Rings create different packed-bed structures.

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5. 25 mm PTFE Pall Ring

The 25 mm class generally moves selection toward:

• more packing elements per cubic meter;
• more geometric contacting surface;
• stronger mass-transfer intensity.

It may deserve stronger consideration when:

• separation or absorption duty is demanding;
• service is relatively clean;
• tower diameter is compatible with smaller packing;
• pressure-drop margin is adequate.

However, smaller packing also means:

• finer bed structure;
• more packing contact points;
• greater sensitivity to fouling.

Therefore:

25 mm should not be selected simply because smaller packing usually provides more area.

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6. 38 mm PTFE Pall Ring

The 38 mm model normally occupies the intermediate position.

It may provide a practical balance between:

• contacting area;
• hydraulic capacity;
• bed openness;
• fouling tolerance.

The 38 mm class often deserves evaluation when a project does not clearly require either:

• maximum contacting intensity;

or

• maximum hydraulic openness.

This makes it a useful candidate for many medium-size industrial packed columns.

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7. 50 mm PTFE Pall Ring

The 50 mm class moves further toward:

• larger characteristic flow passages;
• fewer elements per cubic meter;
• stronger hydraulic-openness potential.

It may deserve stronger consideration where:

• gas throughput is relatively high;
• pressure-drop allowance is limited;
• moderate fouling exists;
• tower diameter is sufficiently large.

The trade-off is that larger packing normally provides less geometric surface per cubic meter than smaller packing.

Therefore:

50 mm should be selected because the tower benefits from additional openness—not simply because larger packing is easier to handle.

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8. 25 vs 38 vs 50 mm: The Main Trade-Off

The preliminary size relationship can be summarized as:

This is a selection direction, not a guaranteed hydraulic-performance table.

Final sizing still depends on real operating conditions.

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9. Why Pall Ring Openings Matter

A conventional closed-wall ring forces more fluid to move:

• through the center;
• around the outside.

Pall Ring openings create additional paths through the side wall.

This can improve:

• internal volume utilization;
• liquid redistribution;
• gas access to internal surfaces.

The engineering intention is therefore to create:

more useful contact without filling the bed with unnecessary solid material.

However, final effective area still depends on whether liquid actually wets and uses those surfaces.

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10. PTFE Does Not Guarantee Better Wetting

This is an important limitation.

Mass transfer depends on more than geometric surface area.

It also depends on:

• surface wetting;
• liquid properties;
• distributor quality;
• liquid rate;
• gas rate.

A high-performance packing geometry cannot compensate for severe liquid maldistribution.

Therefore, PTFE Pall Ring should be treated as part of the complete packed-tower system rather than as an isolated efficiency component.

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11. Chemical Compatibility Comes Before Cost

PTFE is often selected because chemical attack is a serious project risk.

Compatibility evaluation should consider:

• exact chemical species;
• concentration;
• temperature;
• mixed streams;
• cleaning chemicals;
• process upsets.

Do not select a material from pH alone.

For example, two solutions with similar pH may contain completely different chemicals and produce different material-compatibility requirements.

The correct question is:

What substances will actually contact the packing throughout its operating life?

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12. PTFE Pall Ring vs PP Pall Ring

PP Pall Ring is widely used in compatible scrubbers and absorbers because it can provide:

• low bed weight;
• economical molded construction;
• useful chemical resistance.

PTFE may deserve consideration when PP does not provide sufficient:

• chemical compatibility;
• operating-temperature margin.

But if PP safely meets the project requirement:

PTFE may add material cost without providing a corresponding process advantage.

This is especially relevant in large towers containing many cubic meters of packing.

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13. PTFE Pall Ring vs PVDF Pall Ring

PVDF can occupy an important intermediate material position.

DAIER's engineering database separately lists:

• PVDF Pall Ring 25 mm;
• PVDF Pall Ring 38 mm;
• PVDF Pall Ring 50 mm;

and the corresponding PTFE Pall Ring models.

This confirms that the engineering system treats them as different material-selection options.

A practical decision sequence is:

Can PP meet the chemistry and temperature?

If no:

Can PVDF meet them with adequate margin?

If no:

Does PTFE provide the necessary compatibility?

This prevents PTFE from becoming the automatic first choice.

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14. PTFE Pall Ring vs Metal Pall Ring

Metal Pall Ring can offer important advantages:

• thin walls;
• very high void fraction;
• mechanical strength;
• good handling durability.

PTFE Pall Ring may become stronger when:

• metal corrosion is unacceptable;
• alloy cost becomes excessive;
• non-metallic construction is required.

The choice should therefore compare:

Metal hydraulic/mechanical advantages

with:

PTFE chemical-material advantages

rather than assuming one family is always superior.

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15. PTFE Pall Ring vs Ceramic Pall Ring

Ceramic Pall Ring may also be considered for aggressive or high-temperature processes.

Ceramic Pall Ring

Can offer:

• strong temperature capability;
• resistance to many chemical systems;
• lower material cost in some projects.

But it is:

• heavy;
• brittle;
• chemically unsuitable for certain environments.

PTFE Pall Ring

Can provide:

• a different chemical-compatibility profile;
• polymeric construction;
• resistance to impact breakage compared with brittle ceramic.

But PTFE can involve:

• higher raw-material cost;
• significant packed-bed weight relative to PP;
• material-specific mechanical and temperature constraints.

The final decision must come from the actual process environment.

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16. Fouling Changes the Size Decision

PTFE itself does not make a packed bed immune to fouling.

Deposits can still accumulate around:

• Pall Ring windows;
• internal tabs;
• packing contact points.

Possible foulants include:

• scale;
• solids;
• crystallized salts;
• polymeric deposits;
• biological material.

As fouling severity increases, selection may shift:

25 mm → 38 mm → 50 mm

to create larger flow passages.

But severe fouling may justify choosing an entirely different, more open packing geometry.

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17. Tower Diameter Still Matters

Packing size must be reasonable relative to tower ID.

A 50 mm PTFE Pall Ring in a very small tower may create:

• excessive wall effects;
• too few elements across the tower diameter;
• poorer bed uniformity.

Conversely, 25 mm packing in a large dirty scrubber may create an unnecessarily fine bed.

The correct selection therefore combines:

Tower Diameter + Packing Size

rather than treating packing size independently.

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18. Bed Weight Needs Attention

PTFE has substantially greater material density than commonly used PP.

DAIER's internal engineering database also treats 25, 38 and 50 mm PTFE Pall Rings as different packed-density classes.

Those internal values are useful for preliminary screening but should not replace the final approved supplier datasheet.

For project calculations, confirm:

• actual bulk density;
• packed volume;
• wet operating load.

This becomes particularly important when replacing lightweight PP packing with PTFE.

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19. Support Grid and Hold-Down Review

A PTFE Pall Ring retrofit should include the tower internals.

The support grid must:

• retain the selected packing size;
• carry the packed-bed operating load;
• provide adequate open area.

If the packing is lightweight enough to move under abnormal gas loading, the hold-down arrangement may also require review.

A hold-down device should:

restrain packing movement

rather than compress the bed.

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20. Where PTFE Pall Ring May Be a Strong Candidate

PTFE Pall Ring deserves stronger consideration when several conditions occur together:

• aggressive process chemistry;
• ordinary plastic materials have insufficient compatibility;
• metal corrosion is problematic;
• ceramic is undesirable or incompatible;
• random packing is preferred;
• Pall Ring hydraulic geometry suits the process.

Possible process categories may include suitable:

• chemical absorbers;
• specialty chemical scrubbers;
• corrosive stripping systems;
• high-purity chemical processing.

Actual suitability remains process-specific.

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21. When PTFE Pall Ring May Be the Wrong Choice

Its priority should decrease when:

• PP already provides adequate compatibility;
• PVDF provides adequate margin at lower project cost;
• severe fouling favors a simpler or more open geometry;
• structured packing better fits demanding separation requirements;
• support-load restrictions are important;
• the process does not justify PTFE cost.

The correct material is:

the least complicated material that reliably meets the process requirement

—not automatically the most chemically resistant option available.

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22. Replacement Applications

PTFE Pall Ring may be considered when replacing:

• degraded PP Pall Rings;
• unsuitable PVDF packing;
• corroded metal Pall Rings;
• existing PTFE Pall Rings;
• PTFE Raschig Rings where different hydraulics are desired.

Before conversion, collect:

• existing product and size;
• tower ID;
• packed height;
• support-grid details;
• liquid distributor;
• gas and liquid loads;
• operating temperature;
• actual process chemistry;
• reason for replacement.

This helps determine whether the problem is truly:

• material-related;
• hydraulic;
• fouling-related;
• distribution-related.

Changing material cannot correct every packed-tower problem.

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PTFE Pall Ring Preliminary Decision Guide

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Common Selection Mistakes

Selecting PTFE Because It Sounds More Reliable

Material choice must solve an actual process compatibility requirement.

Treating PTFE Pall Ring and PTFE Raschig Ring as the Same Packing

The material may be the same, but their geometries are different.

Choosing 25 mm Only for Higher Surface Area

Hydraulic and fouling margins may become insufficient.

Choosing 50 mm Only for Greater Openness

The process may require more contacting area.

Assuming PTFE Solves Fouling

Fouling is mainly a process and geometry issue, not simply a material issue.

Ignoring Tower Diameter

Packing size must remain compatible with column geometry.

Using Internal Screening Values as Final Procurement Specifications

Final physical properties should come from the approved production datasheet.

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Frequently Asked Questions

What is PTFE Pall Ring?

PTFE Pall Ring is an open-wall fluoropolymer random packing combining Pall Ring geometry with PTFE material.

What sizes are in DAIER's current engineering database?

The database contains approximately 25, 38 and 50 mm PTFE Pall Ring models.

Is PTFE Pall Ring better than PP Pall Ring?

Not automatically. PTFE is mainly justified when the process chemistry or operating conditions exceed the practical capability of PP.

Is PTFE better than PVDF for Pall Rings?

It depends on the actual chemical exposure, temperature and project economics. If PVDF provides adequate compatibility, PTFE may not be necessary.

Is PTFE Pall Ring better than PTFE Raschig Ring?

Neither is universally better. Pall Ring provides a more open, internally structured flow geometry, while Raschig Ring provides a simpler cylindrical geometry.

Which PTFE Pall Ring size should be selected?

25 mm generally moves toward greater contacting intensity, 38 mm toward a balanced position, and 50 mm toward greater hydraulic openness.

Can PTFE Pall Ring be used in fouling service?

Moderate fouling may favor larger sizes, but severe scale, solids or crystallization may require a different packing geometry.

Can PTFE Pall Ring replace metal Pall Rings?

Potentially, especially where corrosion drives the material change, but bed weight, hydraulics, size and tower internals should be reviewed.

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Selection Takeaway

PTFE Pall Ring should be selected through two separate decisions: first justify PTFE as the required material, then select the Pall Ring size according to the tower's hydraulic and mass-transfer constraints.

The engineering direction is:

25 mm → Greater Contacting Intensity

38 mm → Balanced Mass Transfer and Capacity

50 mm → Greater Hydraulic Openness

The correct sequence is:

Process Chemistry → Temperature → PTFE Justification → Fouling → Gas/Liquid Load → 25/38/50 mm Selection → Tower Diameter → Support Review

The key principle is:

Choose PTFE Pall Ring because both its material and its open Pall Ring geometry solve real project requirements—not simply because PTFE is considered a higher-grade polymer.