What Is Plastic Ralu Ring Packing? Structure, Applications and Selection Boundaries

Plastic Ralu Ring packing is an open random packing used in absorption, scrubbing, stripping and other gas-liquid contacting towers where corrosion resistance, low packing weight and a balance between mass-transfer area and hydraulic capacity are important.

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

The useful engineering question is:

When does Ralu Ring geometry provide a better balance of surface area, void space, pressure-drop tendency and fouling tolerance than other plastic random packing?

DAIER's catalog-confirmed engineering database contains Plastic Ralu Ring models from approximately 15 mm to 125 mm, confirming that this is a multi-size product family with significantly different surface-area and bed characteristics across the range.

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1. What Is Plastic Ralu Ring Packing?

Ralu Ring belongs to the random packing family.

Individual elements are loaded randomly into the tower rather than installed as ordered modules.

The packing uses an open molded ring structure intended to create:

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

Its geometry is more developed than a simple Raschig Ring and is intended to provide useful mass transfer without excessively restricting the packed bed.

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2. Why Is Ralu Ring Different from a Simple Plastic Ring?

A basic cylindrical ring contains substantial wall area but relatively simple flow passages.

More developed plastic ring geometries use:

• openings;
• ribs;
• internal surfaces;
• shaped flow paths

to improve how gas and liquid move through the bed.

Ralu Ring belongs to this more open generation of plastic random packing.

The objective is to improve the balance between:

Contacting Surface + Bed Openness + Liquid Drainage

rather than simply increasing the amount of plastic inside the tower.

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3. Why Size Matters So Much

Ralu Ring is available across a broad size range.

DAIER catalog data includes nominal sizes around:

• 15 mm;
• 25 mm;
• 38 mm;
• 50 mm;
• 90 mm;
• 125 mm. 

This range creates very different engineering positions.

Smaller sizes generally provide more geometric surface area.

Larger sizes generally provide more open flow paths and lower element count per cubic meter.

Therefore:

“Ralu Ring” is not one hydraulic product. Size selection is a major part of the product decision.

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4. Small Ralu Ring Sizes

Smaller models may be attractive when:

• mass-transfer intensity is important;
• tower diameter is relatively small;
• service is clean;
• hydraulic load is moderate.

Greater surface-area density can support more gas-liquid contacting opportunity.

But smaller packing can also create:

• greater hydraulic resistance;
• increased plugging sensitivity;
• higher element count;
• more restrictive bed structure.

The smallest model should therefore not automatically be selected.

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5. Large Ralu Ring Sizes

Larger models may become attractive when:

• gas throughput is high;
• pressure drop matters;
• moderate fouling exists;
• large flow passages are desirable.

They can provide greater hydraulic openness.

However, increasing size generally reduces the available contacting area per unit packed volume.

Therefore:

Large Ralu Ring sizes should not be selected only because they appear safer hydraulically.

The bed still needs enough mass-transfer capability.

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6. Why Plastic Construction Is Important

Plastic Ralu Ring can provide:

• relatively low weight;
• corrosion resistance in compatible chemistry;
• economical molded construction;
• easy handling.

This makes it relevant to many:

• FRP scrubbers;
• plastic absorbers;
• chemical gas-treatment systems.

But material compatibility remains a separate decision.

A suitable Ralu Ring geometry made from the wrong polymer is still unsuitable.

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7. PP Ralu Ring

PP can be attractive where:

• operating temperature remains within its practical range;
• chemical compatibility is acceptable;
• low bed weight is useful;
• cost matters.

However, PP should not be approved solely because:

the process is acidic

or:

the pH is low.

Compatibility should be checked against:

• actual chemicals;
• concentration;
• temperature;
• oxidizers;
• organic solvents.

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8. Absorption Applications

Plastic Ralu Ring can be considered in gas absorption towers where the project requires:

• useful mass-transfer area;
• corrosion-resistant packing;
• manageable pressure drop;
• moderate-to-high gas capacity.

Possible applications include suitable:

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

The required packing size and bed height should be selected from actual process duty.

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9. Scrubber Applications

Ralu Ring can be relevant to scrubbers where engineers need a balance between:

• gas throughput;
• liquid circulation;
• mass transfer;
• fouling tolerance.

Smaller sizes may provide more area.

Larger sizes may provide more hydraulic openness.

This makes the product family useful where a scrubber designer wants to choose among several sizes rather than use one generic packing geometry.

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10. Stripping Applications

Ralu Ring may also be evaluated for stripping service.

The packing must support:

• upward gas or steam flow;
• downward liquid drainage;
• repeated gas-liquid contact.

Its suitability depends on:

• stripping target;
• gas and liquid load;
• temperature;
• polymer compatibility;
• allowable pressure drop.

Higher-temperature stripping may move the project toward another material family.

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11. Pressure-Drop Considerations

Ralu Ring should not be described as having universally low pressure drop.

Its hydraulic behavior changes substantially with packing size.

A small high-area Ralu Ring and a large open Ralu Ring can behave very differently.

Actual pressure drop depends on:

• element size;
• gas velocity;
• liquid rate;
• packed height;
• fluid properties.

Therefore:

Product family name alone is not enough for hydraulic selection.

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12. Fouling Tolerance

Ralu Ring can be used in moderately fouling service when an appropriate size is selected.

Larger sizes may provide greater open passage area.

However, severe:

• scaling;
• crystallization;
• biological growth;
• sticky deposits

can still restrict the bed.

For severe fouling, another more open packing geometry may deserve comparison.

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13. Ralu Ring vs Plastic Pall Ring

Both are open plastic ring-type random packings.

Plastic Pall Ring

Provides:

• highly established industrial use;
• broad availability;
• familiar performance behavior.

Plastic Ralu Ring

Provides:

• a distinct molded geometry;
• a wide size range;
• a different balance of surface area and void structure.

Ralu Ring may be worth considering when its available size or geometry better matches:

• hydraulic capacity;
• mass-transfer requirement;
• fouling condition.

Pall Ring may remain preferable where:

• existing operating history;
• procurement simplicity;
• familiar specification

are more important.

Neither is universally superior.

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14. Ralu Ring vs VSP Ring

Both are plastic random packing families.

VSP Ring generally emphasizes highly open hydraulic geometry.

Ralu Ring spans a broader surface-area and size range.

Therefore, Ralu Ring may deserve stronger consideration when:

• the project needs more flexibility between small high-area and large open sizes.

VSP Ring may be attractive when:

• hydraulic openness is the stronger priority.

The actual product size matters more than the family name alone.

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15. Ralu Ring vs Heilex Ring

Heilex Ring strongly emphasizes:

• large flow passages;
• hydraulic capacity;
• low bed resistance.

Ralu Ring provides a different balance and can offer relatively high surface area at smaller sizes.

Therefore:

Heilex Ring may be more hydraulically oriented, while Ralu Ring can cover a wider efficiency-to-capacity range depending on size.

The final decision should be made from actual process conditions.

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16. Ralu Ring vs Tri-Pack-Type Packing

Tri-Pack-type packing uses a highly open skeletal three-dimensional structure.

Ralu Ring remains more recognizably ring-based.

Tri-Pack-type packing may receive stronger consideration when:

• very high openness;
• fouling tolerance;
• gas capacity

dominate the selection.

Ralu Ring may be stronger when the project requires a broader balance between:

• contacting area;
• hydraulic capacity;
• conventional random-packing behavior.

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17. Tower Diameter Matters

Packing size should be selected relative to tower internal diameter.

A 90 or 125 mm element may be highly open, but it may be inappropriate in a relatively small tower.

If too few elements span the tower cross-section:

• wall effects can increase;
• random bed uniformity can decrease.

Conversely, a very small Ralu Ring in a large dirty tower may create unnecessary:

• pressure drop;
• plugging sensitivity.

Tower ID should therefore be part of the selection.

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18. Retrofit Applications

An existing tower may consider Ralu Ring when replacing:

• older plastic rings;
• damaged packing;
• fouled packing;
• another random packing.

The replacement should review:

• existing packing type;
• nominal size;
• bed height;
• liquid distributor;
• support grid;
• hold-down arrangement;
• operating loads.

A change from one packing geometry to another should not be made on equal volume alone.

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19. Support Grid Compatibility

Different Ralu Ring sizes require appropriate support openings.

The support must:

• retain the packing elements;
• carry the operating bed load;
• maintain adequate open area.

If a smaller Ralu Ring replaces larger packing, support-grid openings should be checked carefully.

For lightweight plastic packing, top restraint may also be required in some systems where bed movement is possible.

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20. When Plastic Ralu Ring Is a Strong Candidate

Ralu Ring deserves stronger consideration when:

• plastic construction is chemically suitable;
• the project wants multiple size options;
• both mass transfer and hydraulic capacity matter;
• absorption or scrubbing duty is involved;
• low packing weight is valuable;
• moderate fouling must be accommodated through size selection.

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21. When It May Not Be the Best Choice

Its priority should decrease when:

• temperature exceeds polymer capability;
• chemistry is incompatible with the selected polymer;
• extremely high separation efficiency is required;
• severe fouling favors much more open packing;
• demanding vacuum service favors structured packing;
• a simpler existing packing already performs adequately.

Selection should solve a real process need rather than add another packing candidate unnecessarily.

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Preliminary Selection Guide

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Common Selection Mistakes

Treating Every Ralu Ring Size as the Same Product

The 15 mm and 125 mm classes solve very different engineering problems.

Choosing the Smallest Size for Maximum Surface Area

This can sacrifice hydraulic margin.

Choosing the Largest Size for Minimum Pressure Drop

This can reduce effective mass-transfer area and create tower-diameter concerns.

Assuming Plastic Means Universal Chemical Compatibility

Actual chemical service must be reviewed.

Comparing Ralu Ring and Pall Ring Without Matching Size

A meaningful comparison should normalize nominal size and operating duty.

Replacing Existing Packing by Equal Volume

Different geometry and size can change both mass transfer and hydraulics.

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Frequently Asked Questions

What is Plastic Ralu Ring packing?

Plastic Ralu Ring is an open molded random packing designed to provide a balance between gas-liquid contacting area and hydraulic capacity.

What sizes are available?

DAIER's catalog-confirmed database includes Ralu Ring sizes from approximately 15 mm to 125 mm.

Is Ralu Ring random packing?

Yes. Individual elements are randomly loaded into the tower.

What is Ralu Ring used for?

It may be used in absorption, scrubbing, stripping and other gas-liquid contacting towers where plastic material and random packing are appropriate.

Is Ralu Ring better than Pall Ring?

Not universally. The two products use different geometries and should be compared by size, process duty, hydraulic requirement, fouling and cost.

Is Ralu Ring suitable for fouling service?

Larger sizes may provide useful fouling tolerance, but severe solids, crystallization or sticky deposits still require caution.

Is smaller Ralu Ring more efficient?

Smaller sizes generally provide greater geometric area, but they can also increase hydraulic resistance and plugging sensitivity.

Can Ralu Ring replace Plastic Pall Rings?

Potentially, but size, hydraulics, mass transfer, bed height and support-grid compatibility should be reviewed before substitution.

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Selection Takeaway

Plastic Ralu Ring is best understood as a multi-size random packing family that can be tuned toward either greater contacting area or greater hydraulic openness depending on nominal size.

Its engineering strength is therefore not one fixed claim such as:

low pressure drop

or:

high efficiency.

Its real value is:

Size Flexibility + Plastic Corrosion Resistance + Low Weight + Adjustable Efficiency/Capacity Balance

The correct decision sequence is:

Process Duty → Required Mass Transfer → Hydraulic Capacity → Fouling → Packing Size → Polymer Compatibility → Temperature → Tower Diameter

The key principle is:

Choose Ralu Ring by matching the specific size and material to the tower—not by treating every Ralu Ring model as the same packing solution.