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Mixed Bed Deionizer (Polishing Ion Exchanger)
Mixed bed polishing demineralizers using strong acid cation and strong base anion resins to produce ultrapure water with resistivity up to 18 MΩ·cm. Used downstream of RO or two-bed deionization.
Outlet Resistivity
15 – 18.2 MΩ·cm
Outlet Conductivity
< 0.1 μS/cm
Flow Rate
0.5 – 50 m³/h
Resin Ratio
Cation : Anion = 1 : 2 (volume)
Overview
Mixed bed deionizers are the standard polishing step for ultrapure water (UPW) production. By intimately mixing strong acid cation resin (H+ form) and strong base anion resin (OH- form) in a single vessel, the ion exchange reactions go nearly to completion — achieving water purity that neither bed alone can reach. The result is water with resistivity of 15–18.2 MΩ·cm, meeting SEMI, ASTM Type I, and USP standards for semiconductor, pharmaceutical, and laboratory applications.
Engineering Features
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Ultrapure Water Quality
Outlet resistivity 15–18.2 MΩ·cm (conductivity < 0.055 μS/cm) with Type II resin quality. Endotoxin and TOC control optional.
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Internal or External Regeneration
External regeneration (off-site service exchange) is standard for small systems — no chemicals on-site. Internal (on-site) regeneration with H₂SO₄ and NaOH available for larger systems.
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Inline Quality Monitoring
Resistivity (or conductivity) meter with alarm and automatic diversion at breakthrough. Optional TOC and silica monitoring.
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Resin Quality
Premium Type I and Type II mixed bed resin. Nuclear-grade and ultrapure semiconductor-grade resins available for critical applications.
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Vessel Construction
304 or 316L stainless steel with internal lining options. Inert distributors (PTFE, PP) prevent resin contamination. Dead-leg-free design for pharmaceutical applications.
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Compact Skid
Pre-piped, pre-wired skid assembly with vessels, conductivity meter, resin trap, and all valving — ready to connect to feed water and drain.
Technical Specifications
Typical Applications
- 💻 Semiconductor Manufacturing — SEMI Grade 1 & 2 UPW for wafer cleaning, photolithography, and CMP.
- 💊 Pharmaceutical & Biotech — USP Purified Water polishing; Water for Injection (WFI) systems.
- 🔬 Laboratory & Research — ASTM Type I water for analytical instruments, cell culture, and reagent preparation.
- ⚡ Power Generation — High-purity boiler feed water and turbine cooling water for power plants.
- 🔋 Battery Manufacturing — Process water for lithium battery and fuel cell manufacturing.
- 🏭 Precision Parts Manufacturing — Rinse water for metal parts, optics, and medical devices.
Frequently Asked Questions
What is the difference between RO water and mixed bed deionized water?
RO typically produces water at 1–10 MΩ·cm (90–99% ion removal). Mixed bed deionizer polishes this to 15–18.2 MΩ·cm (>99.99% ion removal). For semiconductor and pharmaceutical applications, RO alone is never sufficient — MB polishing is required.
How long do mixed bed resins last before exhaustion?
This depends on the feed water quality (from RO or two-bed DI). With RO feed water at ~10 MΩ·cm, a properly sized MB vessel runs 1,000–3,000 hours before breakthrough. We design run times based on your actual feed quality.
Do I need to regenerate on-site?
Most customers use service exchange — exhausted vessels are swapped for fresh regenerated vessels by a service company. This avoids storing acid and caustic on-site. We can supply vessels and arrange exchange service logistics.
What TOC level can I achieve?
With new pharmaceutical-grade resin: < 10 ppb TOC typical. With optimized system design and UV oxidation: < 1 ppb. Specify your TOC requirement and we will engineer accordingly.
Lead time?
Standard vessels: 20–30 days. Complete UPW system with RO + MB: 35–60 days depending on scope.
Often Specified Together
Water Softeners
RO Membrane Housings
Stainless Steel Tanks
Need a Custom Mixed Bed Deionizer (Polishing Ion Exchanger)?
Send us your water analysis and required capacity. Our engineers will respond with a sized proposal and budget within 24 hours.
📧 sales@szhrscl.com | 📱 +86 138 2871 5252