LEWATIT® MonoPlus S 108

Summary

Product Identification

Lewatit® MonoPlus S 108 (H) is a strongly acidic, gel-type cation exchange resin in the Na-form with uniform-sized beads (monodisperse), based on a styrene-divinylbenzene copolymer. It is also available in the hydrogen form (Lewatit® MonoPlus S 108 H).

Key characteristics:

• Extremely resistant to chemical, osmotic, and mechanical stress.
• Very low leachables, even under critical conditions.
• High total capacity with low ionic leakage and low regenerant consumption.
• High monodispersity (uniformity coefficient: max. 1.05) and low fines content (max. 0.1% < 0.4 mm) result in low pressure losses.
• Complies with FDA regulation CFR 21 173.25.

Applications

• Demineralization of water for industrial steam generation (co-current or counter-current systems).
• Polishing using the Lewatit® Multistep System or a conventional mixed bed arrangement.

Resin Bed Features

• High flow rates during regeneration and loading.
• High operating capacity at low regenerant consumption.
• Low rinse water requirement.
• Homogeneous throughput of regenerants, water, and solutions.
• Virtually linear pressure drop gradient, allowing higher bed depths.
• Low TOC emission and high resistance to oxidative stress.
• Good separation of components in mixed bed applications.

Recommended Operating Conditions

• Operating temperature, max. 120 °C (250°F)
• Operating pH range 0-14
• Bed depth, min. 800 mm (2.62 ft)
• Bed depth, max. 3000 mm (9.84 ft)
• Bed expansion at 20°C (approx.) 4 % per m/h (4.5% for H-form)
• Freeboard for internal/external backwashing 60-100% of installed resin volume
• Flow rates:
  • Service: 5-60 m/h (2.04-24.57 gpm/ft²)
  • Backwash* at 20°C: 15-25 m/h (6.14-10.23 gpm/ft²)

* Backwash until the effluent is clear (min. 20 minutes).

Regeneration Parameters

Operating Capacity

Operating capacity is influenced by regenerant dosage, ion ratios (mono/bivalent cations, bicarbonate), water temperature, endpoint conductivity, ionic loading rate, and bed depth. Diagrams are provided in the original document to calculate operating capacity under various conditions for both co-current and counter-current operations using HCl or H₂SO₄ as regenerants.

Sodium Leakage

Sodium leakage is affected by the regenerant amount, the proportion of monovalent cations, and bicarbonate content. Leakage increases with higher monovalent cation proportion and decreases with higher regenerant consumption. Diagrams are provided to estimate average sodium leakage in co-flow operation with HCl or H₂SO₄ regeneration.

Hydraulic Characteristics

Bed Expansion

• Monodispersity of Lewatit® MonoPlus S 108 significantly reduces backwash water demand.
• Bed expansion is dependent on linear flow rate and resin form (Na, H, Ca).
• Diagrams illustrate bed expansion as a function of linear flow rate and temperature.

Pressure Drop

• The specific pressure loss for Lewatit® MonoPlus S 108 or S 108 H at 15°C (59°F) is approximately 1.0 kPa x m⁻² x h (or 4.425 psi/ft).
• Pressure drop calculations consider resin bed depth, linear velocity, velocity factor, temperature factor, and resin factor.
• Pressure drop for non-classified resin layers (e.g., in mixed beds) is approximately 20% higher.
• The pressure drop of the unit itself (nozzles, gravel, etc.) must also be considered.

Mixed Bed Combination

Lewatit® ion exchange resins with monodisperse bead size distribution (UC max. 1.05) are suitable for mixed bed systems. Their uniform bead size reduces cross-contamination and improves separation behavior.

• Uniformity Coefficient (UC): Max. 1.05.
• Fines Content: Max. 0.1% (< 0.4 mm).
• Key factors for effective separation and regeneration in mixed beds include resin density, contrasting colors, and uniform bead size.

Disclaimer: Extraction may miss figures, footnotes, or revisions; contractual data must match the OEM PDF revision used on the project.

Official datasheet (PDF)

Lenntech datasheet mirror