What Is Plastic Pentagon Ring Packing? Structure, Size Range and Selection Boundaries

Plastic Pentagon Ring packing is an open molded random packing used in gas-liquid contacting towers where engineers need a combination of substantial surface area, high void fraction, low material weight and corrosion-resistant polymer construction.

It belongs to the plastic random-packing family, but it should not be treated as merely another name for a Pall Ring.

The real selection question is:

When does the surface-area and void-space balance of Pentagon Ring packing provide a useful advantage over other plastic random packing geometries?

DAIER's catalog-aligned engineering database contains Pentagon Ring models in approximately 38, 50 and 76 mm classes, with substantial specific surface area and high void fraction across the series.

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1. What Is Plastic Pentagon Ring Packing?

Pentagon Ring is a plastic random packing.

Individual elements are loaded randomly into the packed bed rather than assembled into structured layers.

It uses a molded open geometry designed to provide:

• gas-flow passages;
• liquid-contacting surfaces;
• substantial void space;
• repeated liquid redistribution.

Because product geometry can vary by supplier, the actual:

• dimensions;
• surface area;
• void fraction;
• bulk density

should be confirmed from the approved datasheet rather than relying only on the name “Pentagon Ring.”

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2. What Sizes Are Available?

DAIER's catalog-confirmed product data includes three Pentagon Ring models:

These figures show something important:

Pentagon Ring maintains relatively high specific surface area even as packing size increases.

That gives the product a different engineering position from extremely open plastic packing whose surface area may fall much more sharply with size.

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3. Why Is Specific Surface Area Important?

Specific surface area indicates the geometric area available within a unit volume of packing.

Greater area can provide more opportunity for:

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

The 38 mm Pentagon Ring in the catalog dataset provides approximately 246 m²/m³, while the 50 mm model remains around 218 m²/m³.

This makes the product worth evaluating where mass-transfer area remains important but a plastic random packing is preferred.

However:

Higher surface area does not automatically mean better tower performance.

Hydraulic loading and fouling must also be considered.

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4. Why Is High Void Fraction Important?

The listed Pentagon Ring series has approximately 95–97% void fraction.

High void space can support:

• gas passage;
• liquid drainage;
• hydraulic capacity.

This creates an interesting engineering combination:

Relatively High Surface Area + High Void Fraction

But void fraction alone does not determine:

• operating pressure drop;
• flooding point;
• final capacity.

Those remain dependent on the actual tower and operating conditions.

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5. 38 mm Pentagon Ring

The 38 mm class provides the highest listed surface area within the catalog series.

It may deserve stronger consideration when:

• contacting intensity matters;
• service is reasonably clean;
• tower diameter is compatible;
• pressure-drop margin remains acceptable.

Its smaller element size also means a greater number of pieces per cubic meter.

The catalog data lists approximately 46,000 pieces/m³ for this model.

This can create more frequent gas-liquid interaction, but it can also increase sensitivity to fouling compared with larger packing.

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6. 50 mm Pentagon Ring

The 50 mm class provides a particularly interesting balance.

Catalog values are approximately:

• 218 m²/m³ surface area;
• 97% void fraction;
• 107 kg/m³ bulk density. 

This makes the 50 mm model worth evaluating where the project needs:

• substantial contacting area;
• high bed openness;
• industrial gas throughput.

It should not automatically be considered superior to 38 or 76 mm.

The operating requirement determines which balance is more useful.

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7. 76 mm Pentagon Ring

The 76 mm class provides:

• larger physical flow passages;
• lower bulk density;
• fewer packing elements per unit volume.

Its listed specific surface area remains approximately 198 m²/m³, with about 96% void fraction.

This may make it attractive where:

• gas capacity is important;
• some fouling tolerance is needed;
• a large plastic packing is appropriate for the tower diameter.

But 76 mm packing should not be used blindly in smaller towers.

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8. Why Packing Size Changes the Decision

As with other random packing, size affects the balance between:

Mass Transfer

and

Hydraulic Openness

Smaller packing may offer:

• more elements;
• greater contact frequency;
• higher surface-area density.

Larger packing may offer:

• larger flow paths;
• greater hydraulic margin;
• greater tolerance for some deposits.

Pentagon Ring therefore needs to be selected at the specific size level, not merely at the product-family level.

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9. Plastic Material Advantages

Plastic construction may provide:

• low packed-bed weight relative to ceramic;
• corrosion resistance in compatible chemistry;
• economical molded geometry;
• easier handling.

This makes Plastic Pentagon Ring relevant to:

• scrubbers;
• absorbers;
• stripping towers;
• chemical gas-treatment systems.

But the actual polymer must be confirmed.

Plastic geometry and material compatibility are two separate engineering decisions.

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10. Polymer Compatibility

A plastic packing should not be approved from pH alone.

Compatibility depends on:

• actual chemical species;
• concentration;
• operating temperature;
• oxidizing conditions;
• solvent exposure;
• required service life.

PP may be appropriate in many services, but it is not universally resistant.

If chemistry exceeds the capability of the selected polymer, another material should be evaluated.

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11. Absorption Applications

Pentagon Ring can be considered in absorption towers where the process needs:

• significant gas-liquid contacting area;
• high bed voidage;
• corrosion-resistant plastic construction.

Potential applications may include suitable:

• chemical absorption;
• exhaust-gas treatment;
• acid-gas scrubbing.

The required removal performance and packed height still depend on the process.

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12. Scrubber Applications

A scrubber often has to balance:

• gas throughput;
• liquid circulation;
• pressure drop;
• mass-transfer requirement;
• fouling.

Pentagon Ring can be attractive where the designer does not want to sacrifice too much surface area while still maintaining a relatively open plastic bed.

This places it differently from extremely open plastic geometries designed mainly around hydraulic capacity.

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13. Stripping Applications

Plastic Pentagon Ring may also be considered in suitable stripping service where:

• temperature remains within polymer limits;
• corrosion resistance is useful;
• random packing is appropriate.

The tower still needs sufficient:

• gas or steam capacity;
• liquid drainage;
• contacting area.

High-temperature stripping may require another material family.

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14. Pressure-Drop Considerations

High void fraction can support favorable hydraulic behavior.

But it would be incorrect to state:

Pentagon Ring always provides lower pressure drop than Pall Ring.

Actual pressure drop depends on:

• packing size;
• gas rate;
• liquid rate;
• tower diameter;
• bed height;
• fluid properties.

Product parameters are useful for preliminary comparison, but final hydraulic performance remains project-specific.

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15. Fouling Tolerance

Pentagon Ring's open structure can provide useful tolerance in some moderately fouling applications.

However, its relatively substantial surface area also means more internal packing structure than extremely open low-area products.

Severe:

• scale;
• crystallization;
• biological growth;
• sticky deposits

can still restrict the bed.

If fouling becomes the dominant process constraint, products such as:

• larger highly open random packing;
• grid-type packing

may deserve stronger consideration.

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16. Pentagon Ring vs Plastic Pall Ring

Both are plastic random packing products.

Plastic Pall Ring

Offers:

• extensive industrial use;
• broad size availability;
• familiar engineering behavior.

Plastic Pentagon Ring

Can provide a different combination of:

• relatively high surface area;
• high void fraction;
• molded open geometry.

Pentagon Ring may deserve consideration when the project wants to preserve significant contacting area while also maintaining a highly open bed.

Pall Ring may remain preferable where:

• proven operating history;
• supplier familiarity;
• standard replacement

are priorities.

Neither is universally better.

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17. Pentagon Ring vs Hiflow Ring

This is a useful engineering boundary.

Hiflow Ring covers a wide range from:

• high-area small models

to

• highly open large models.

Pentagon Ring, based on the catalog-confirmed series, retains relatively substantial surface area even at larger nominal classes.

Pentagon Ring may therefore deserve stronger evaluation where:

• mass-transfer area remains a major priority.

A large Hiflow Ring may be more attractive where:

• maximum openness;
• low weight;
• fouling tolerance

receive greater priority.

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18. Pentagon Ring vs Snowflake Ring

Snowflake Ring generally emphasizes:

• very open passages;
• hydraulic robustness;
• fouling tolerance.

Pentagon Ring provides a different balance with greater emphasis on:

• contacting area;
• high void fraction together.

Therefore:

Pentagon Ring may be more mass-transfer-oriented, while Snowflake Ring may be more openness-oriented.

The actual process should determine which direction is appropriate.

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19. Pentagon Ring vs Tri-Pack-Type Packing

Tri-Pack-type packing is another open three-dimensional plastic packing.

The two should not be compared from appearance alone.

Relevant variables include:

• specific surface area;
• void fraction;
• nominal size;
• bulk density;
• required mass transfer;
• fouling risk;
• gas throughput.

If the main requirement is very high gas capacity, Tri-Pack-type packing may deserve stronger consideration.

If maintaining greater contacting area is important, Pentagon Ring may be a meaningful candidate.

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20. Tower Diameter Matters

The 38, 50 and 76 mm models should not be used interchangeably.

A 76 mm packing element can become too large relative to a small tower diameter.

This may result in:

• stronger wall effects;
• fewer elements across the tower;
• less representative random-bed structure.

Conversely, selecting 38 mm packing in a large fouling-prone tower may create unnecessary restriction.

Tower diameter should therefore be part of the size decision.

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21. Retrofit Applications

Pentagon Ring may be evaluated when replacing:

• Plastic Pall Rings;
• older plastic random packing;
• damaged or chemically degraded packing.

But replacement should review:

• current packing size;
• tower ID;
• bed height;
• liquid distributor;
• support grid;
• hold-down arrangement;
• operating load.

Equal volume does not mean equal performance.

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22. Support Grid Compatibility

A new packing size must be physically retained by the existing support.

If smaller Pentagon Rings replace larger random packing, support openings may need review.

The support must provide:

• adequate mechanical strength;
• sufficient open area;
• appropriate element retention.

For lightweight plastic packing, top restraint may also be required in applications where bed movement can occur.

The restraint should control movement rather than compress the packing.

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23. When Plastic Pentagon Ring Is a Strong Candidate

Pentagon Ring deserves stronger consideration when:

• plastic material is compatible;
• substantial surface area is required;
• high void fraction is valuable;
• absorption or scrubbing duty is involved;
• random packing installation is preferred;
• the project needs a balance between efficiency and hydraulic capacity.

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24. When It May Not Be the Best Choice

Its priority should decrease when:

• extreme fouling dominates the tower;
• very large open passages are the main requirement;
• operating temperature exceeds polymer capability;
• the chemistry attacks the selected polymer;
• extremely high separation efficiency favors structured packing;
• a conventional packing already meets the process requirement more economically.

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Preliminary Selection Guide

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Common Selection Mistakes

Treating All Pentagon Ring Sizes as Equivalent

38, 50 and 76 mm have different surface area, density and bed behavior.

Choosing 38 mm Only Because It Has the Highest Surface Area

Hydraulic margin and fouling must still be acceptable.

Choosing 76 mm Only Because It Is Larger

Tower diameter and required mass-transfer area may reject that choice.

Assuming High Void Fraction Guarantees Low Pressure Drop

Pressure drop remains operating-condition dependent.

Assuming Plastic Means Universal Corrosion Resistance

Actual polymer compatibility must be checked.

Comparing Pentagon Ring With Pall Ring Without Matching Size

A meaningful comparison requires actual candidate models.

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Frequently Asked Questions

What is Plastic Pentagon Ring packing?

Plastic Pentagon Ring is an open molded random packing designed to combine substantial gas-liquid contacting area with high bed void fraction.

What sizes are available?

DAIER's catalog-aligned product data includes approximately 38, 50 and 76 mm Pentagon Ring classes.

Which size has the highest surface area?

Within this verified series, the 38 mm model has the highest listed specific surface area at approximately 246 m²/m³.

Which model has the highest void fraction?

The 50 mm catalog model is listed at approximately 97% void fraction.

Is Pentagon Ring better than Pall Ring?

Not universally. Pentagon Ring provides a different balance of surface area and void fraction, while Pall Ring may provide advantages in proven service history, availability and standardization.

Is Pentagon Ring suitable for scrubbers?

It can be a strong candidate where compatible plastic material, substantial contacting area and good hydraulic openness are required.

Is Pentagon Ring suitable for fouling service?

Moderate fouling may be manageable with an appropriate size, but severe solids, scaling or crystallization may favor a more open packing geometry.

Can Pentagon Ring replace Plastic Pall Ring?

Potentially, but the replacement should review size, hydraulic behavior, mass-transfer requirement, bed height and support-grid compatibility.

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Selection Takeaway

Plastic Pentagon Ring occupies an interesting position between high-area compact plastic random packing and extremely open low-area packing.

Its verified product series combines:

Relatively High Surface Area + High Void Fraction + Plastic Corrosion Resistance

which can make it worth evaluating for:

• absorbers;
• scrubbers;
• stripping systems;
• compatible chemical gas treatment.

The correct selection sequence is:

Process Duty → Required Mass Transfer → Gas/Liquid Load → Fouling → Packing Size → Tower Diameter → Polymer Compatibility → Temperature

The key principle is:

Choose Pentagon Ring when the tower needs both substantial contacting area and an open plastic bed—not simply because the geometry is different from a Pall Ring.