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Sodium Hypochlorite Generators with Ru-Ir MMO Titanium Electrodes

Q: How does a sodium hypochlorite generator work?

A dilute salt brine or seawater is passed through an electrolytic cell fitted with Ru-Ir MMO coated titanium electrodes. The direct current converts dissolved chloride into sodium hypochlorite on site, producing only the quantity required.

Q: Which electrode coating is used for chlorine evolution?

Ruthenium-iridium mixed metal oxide (RuO2-IrO2) is the standard coating for chlorine evolution in chloride electrolytes, holding a stable potential and tolerating the oxidising hypochlorite environment.

Q: Why is Ru-Ir used here instead of Ir-Ta?

Ir-Ta MMO is optimised for oxygen evolution in acidic electrolytes, while Ru-Ir MMO has lower overpotential and better selectivity for chlorine evolution in chloride duty.

Q: What feed water is required?

On-site generators run on dissolved salt brine (typically 25-40 g/L) or seawater. Feed hardness should be controlled because calcium and magnesium scale on the electrode surface and shorten life.

Q: How long do the electrodes last?

Electrode life depends on coating chemistry, loading, current density, brine quality and duty cycle. Design life is confirmed per order against accelerated life test data.

Q: How is scaling controlled?

Periodic acid cleaning removes carbonate scale from hard feed water. Electrode gap and cleaning intervals are sized for your hardness.

Q: Is hydrogen produced during electrolysis?

Yes, hydrogen is evolved at the cathode. Systems include gas separation, venting and ventilation so concentration stays well below the lower explosive limit.

Q: What strength of hypochlorite does the system produce?

Typical on-site output is a low-strength solution around 3-4.5 g/L equivalent free chlorine, dosed as generated; the exact strength is confirmed per order.

Q: Can you supply replacement electrodes for existing cells or pools?

Yes. Send cell dimensions, connection arrangement and operating data, and Ru-Ir MMO drop-in electrodes are fabricated with the same format and rating.

Q: What is the lead time and what documents ship with the order?

Standard electrodes typically ship in 2-4 weeks; systems are scheduled against the project. Orders ship with MTC, coating report, XRF data, ALT data, inspection record and certificate of conformity.

Electrolytic sodium hypochlorite generator systems that produce chlorine disinfectant on site from salt brine or seawater — powered by ruthenium-iridium MMO coated titanium electrodes rated for chlorine evolution. From pool chlorinators to municipal water disinfection, the system removes chlorine gas transport and bleach strength decay, with electrode life verified by accelerated testing and confirmed per order.

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Swimming PoolsDrinking WaterCooling WaterCIP & Sanitizing

1–100+ kg/dayChlorine Output

3–4.5 g/LElectrolyte Strength

0.5–2 kA/m²Current Density

24hEngineering Response

Sodium hypochlorite generator system with MMO titanium electrodes installed for on-site chlorination

Engineering Reality

Sodium Hypochlorite Is Generated On Site, Not Shipped

On-site chlorination runs dilute brine (or seawater) through an electrolytic cell where Ru-Ir MMO coated titanium electrodes convert dissolved chloride into sodium hypochlorite. Unlike bulk chemical delivery, the system produces only the disinfectant you use — at a stable 3–4.5 g/L equivalent strength — so there is no chlorine gas transport, no pressurised containers and no hypochlorite stock that degrades on the shelf.

The electrode is the working heart of the cell. A ruthenium-iridium mixed metal oxide coating is selected for chlorine evolution: it holds a stable potential in the chloride electrolyte, tolerates the oxidising environment, and is sized so current density stays within the coating rating. Ehisen builds the coated electrodes to your cell geometry — mesh, plate or tubular — and verifies coating loading and accelerated life before shipment.

Electrolytic sodium hypochlorite generator unit producing disinfectant on site

The engineering boundary: chlorine evolution is an aggressive duty — brine quality, hardness, temperature and current density all control electrode life. We rate the coating chemistry, precious-metal loading and current density to your water chemistry and duty cycle before quoting, and confirm service life per order rather than as a fixed figure.

The Challenges

What Limits Conventional Chlorine & Bleach Systems

Four constraints dominate hypochlorite supply — each is removed by generating the disinfectant on site with the right electrode set.

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Chlorine Gas Logistics & Safety

Transporting pressurised chlorine gas or bulk bleach across public roads carries permitting, handling and spill risk. On-site generation removes the hazardous supply chain entirely.

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Bleach Strength Decay

Bulk sodium hypochlorite loses active chlorine steadily in storage — strength can fall noticeably within weeks. Facilities then over-dose to compensate and lose dosing accuracy.

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Electrode Fouling & Scaling

Hard water and poor brine quality deposit scale on the electrode surface, raising cell voltage and shortening life. Coating and cell design must tolerate the feed you actually have.

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Maintenance & Dosing Drift

Conventional dosing systems drift as chemical strength changes, and electrodes that are not rated for the duty fail early. Predictable electrode life and controlled current keep output and dosing stable.

Selection Boundary

This page covers: electrolytic sodium hypochlorite generators and their core consumable — Ru-Ir MMO coated titanium electrodes rated for chlorine evolution — for swimming pools, drinking water, cooling water, CIP and sanitizing duty.

This page does not cover: anodes for oxygen evolution or non-chloride electrolytes. For oxygen-evolution duty see Iridium-Tantalum Titanium Anode; for the wider MMO range see MMO Titanium Anode.

Selection note: brine quality, water hardness, current density and target chlorine output are interdependent — coating chemistry, loading and design life are confirmed together per quotation.

Selection Guide

Match the Generator & Electrode to Your Duty

Use the table as a starting point — our engineers refine it with your feed water chemistry, flow and dosing target.

Application	Recommended Electrode	Coating	Current Density	Life	Key Benefit
Swimming pool chlorination	Ru-Ir MMO plate / tube	RuO₂-IrO₂	Confirmed per order	Confirmed per order	No bulk bleach, stable pool chlorine
Drinking water disinfection	Ru-Ir MMO plate cells	RuO₂-IrO₂	Confirmed per order	Confirmed per order	On-site output, no gas supply
Cooling water treatment	Ru-Ir MMO mesh / tube	RuO₂-IrO₂	Confirmed per order	Confirmed per order	Biofouling control, low dosing drift
Seawater electrolysis	Ru-Ir MMO tube / mesh	RuO₂-IrO₂	Confirmed per order	Confirmed per order	Marine biofouling & disinfection
CIP & food sanitizing	Ru-Ir MMO plate	RuO₂-IrO₂	Confirmed per order	Confirmed per order	Fresh sanitizer made per batch
Wastewater & odor control	Ru-Ir MMO plate / tube	RuO₂-IrO₂	Confirmed per order	Confirmed per order	Rapid oxidation & odor abatement

Feed: salt brine 25–40 g/L · seawater · softened waterCoating basis: RuO₂-IrO₂ for chlorine evolutionSubstrate: Grade 1 / Grade 2 titanium

Product Range

Ehisen Hypochlorite Generation Electrode & System Range

Four core configurations — from replacement electrodes to complete generator systems — each rated to the chloride duty with traceable material and coating documentation.

Ehisen MMO titanium electrode for electrolytic sodium hypochlorite preparation

Cell Electrode

Ru-Ir MMO Electrode for Hypochlorite Cells

Ruthenium-iridium coated titanium mesh, plate or tube designed for the chloride electrolyte of a sodium hypochlorite cell — stable potential and long coating life in chlorine-evolution duty.

Substrate	Gr1 / Gr2 Ti
Coating	RuO₂-IrO₂
Current density	Confirmed per order
Design life	Confirmed per order

Pool Chlorinator

Pool Chlorinator Electrode

Drop-in Ru-Ir MMO electrodes for salt water pool chlorinators — produce free chlorine from dissolved salt with no chemical handling and predictable replacement scheduling.

Substrate	Gr1 / Gr2 Ti
Coating	RuO₂-IrO₂
Cell voltage	Confirmed per order
Design life	Confirmed per order

Salt water pool chlorination system with MMO titanium electrode installed

Salt Water System

Salt Water Pool Chlorination Electrode

Electrode sets for salt water pool systems where the cell runs on low-concentration brine — coating and geometry sized to hold output stable across the swimming season.

Format	Tube / plate / mesh
Coating	RuO₂-IrO₂
Current density	Confirmed per order
Design life	Confirmed per order

Complete System

Sodium Hypochlorite Generator System

Skid-mounted generation units — brine tank, electrolytic cell, rectifier and control — built around Ehisen Ru-Ir MMO electrodes, referenced to the national standard for sodium hypochlorite generators.

Output	Per model (table below)
Cell	Ru-Ir MMO plate cells
Current density	Confirmed per order
Design life	Confirmed per order

Reference Specifications

Electrode Formats & Generator Output Data

Factory reference tables for standard electrode formats and generator models. Other sizes, coatings and precious-metal loadings are produced to drawing and confirmed per order.

Ru-Ir MMO Electrode Format	Form	Coating Loading (g/m²)	Current Density	Application
Plate / tube for hypochlorite cell	Plate · tube	8–15	Confirmed per order	Generator cells · water treatment
Mesh electrode	Expanded mesh	8–15	Confirmed per order	Cooling water · seawater cells
Pool chlorinator electrode	Tube / plate	8–15	Confirmed per order	Salt water pools

Generator System Model	Chlorine Output (g/h)	Cell Type	Electrolyte	Application
On-site hypochlorite system — small	50–500	Ru-Ir MMO plate	3–4.5 g/L NaOCl	Pools · small water systems
On-site hypochlorite system — medium	500–2,000	Ru-Ir MMO plate	3–4.5 g/L NaOCl	Municipal · industrial water
On-site hypochlorite system — large	2,000–10,000+	Ru-Ir MMO plate banks	3–4.5 g/L NaOCl	Utility · seawater duty

Titanium base: ASTM B265 Gr1 / Gr2Output, strength and electrode rating confirmed per order against feed water chemistry

Order Basis

Share the five requests below and we will return a quotation with electrode rating, output and life confirmed together.

Request	Definition
Feed water chemistry	Salt brine / seawater, hardness, temperature
Target chlorine output	kg or g per hour / day, strength required
Electrical duty	Cell current / voltage / power available
Electrode & cell dimensions	Drawing or dimensions, cell layout
Control & documentation	Rectifier, dosing, MTC / coating report / CoC

Minimum order: negotiable per configurationDocuments: MTC · coating report · XRF data · ALT data · inspection record · CoC

Quality & Documentation

Documented Quality for Hypochlorite Electrodes

Every electrode and system ships with traceable material, coating and testing records — so operators can trust output, lifetime and the audit trail.

ISO 9001

Quality Management

Production runs under a certified quality management system with full batch traceability from titanium substrate to final test.

MTC

Material Certificates

Titanium substrate to ASTM B265 Gr1 / Gr2 with chemical and mechanical traceability.

XRF Data

Coating Verification

Coating thickness and ruthenium / iridium loading verified per batch — the parameters that control electrode life and output stability.

ALT Data

Accelerated Life Test

Performance verified per NACE TM0108-2008 at elevated current density in chloride electrolyte under rated conditions.

3rd-Party

Independent Testing

Third-party reports available on request for coating thickness, adhesion and precious-metal loading.

Export Docs

Project Documentation

Certificate of conformity, packing list and inspection records prepared for project handover and audits.

MTCCoating ReportXRF DataALT DataInspection RecordCertificate of ConformityPacking List

Accelerated Life Testing

ALT Conditions per NACE TM0108-2008

Lifetime is verified by accelerated life testing — not field wait. We test at elevated current density in the chloride media your cell actually runs, then convert the data to your operating rating.

Coating System	Medium	Current Density (A/m²)	Temperature (°C)
Ru-Ir MMO	NaCl brine / seawater	20,000	25 ± 5
Ru-Ir MMO	Softened brine (hardness controlled)	20,000	40 ± 5

Coating Quality

Coating Control & Surface Quality

Coating loading and uniformity are measured, not assumed — the parameters that actually control electrode life and chlorine output.

MMO coating inspection on a titanium electrode sample

Coating Loading & Uniformity

Active coating loading is measured and controlled per batch — the value that sets current-density rating and design life.

Titanium anode life extension testing under electrochemical load

Bonding & Thermal Cycling

Adhesion and thermal cycling are checked during production to keep the coating stable under thermal and electrochemical load.

Performance

Specs That Keep Chlorine Output Stable

0.5–2 kA/m²

Rated Current Density

Sustains efficient chlorine evolution without accelerated coating wear or voltage drift — rating confirmed per order against feed water.

3–4.5 g/L

Electrolyte Strength

On-site output in the standard hypochlorite strength band used for dosing — no concentrated chemical handling.

<3%

Coating Loading Tolerance

Controlled precious-metal loading per batch keeps overpotential, efficiency and lifetime consistent across the whole cell bank.

8–15 g/m²

Ru-Ir Loading

Ru-Ir loading verified per batch — the loading level that controls electrode life in chlorine-evolution duty.

FAQ

Frequently Asked Questions

How does a sodium hypochlorite generator work?

A dilute salt brine or seawater is passed through an electrolytic cell fitted with Ru-Ir MMO coated titanium electrodes. The direct current converts dissolved chloride into sodium hypochlorite on site, producing the disinfectant only in the quantity required — no chlorine gas transport, no bulk bleach storage.

Which electrode coating is used for chlorine evolution?

Ruthenium-iridium mixed metal oxide (RuO₂-IrO₂) is the standard coating for chlorine evolution in chloride electrolytes. It holds a stable potential, tolerates the oxidising hypochlorite environment, and is rated together with current density and life per order.

Why is Ru-Ir used here instead of Ir-Ta?

Ir-Ta MMO is optimised for oxygen evolution in acidic electrolytes, while Ru-Ir MMO has lower overpotential and better selectivity for chlorine evolution in chloride duty. Matching the coating to the target reaction is what keeps voltage, efficiency and life under control.

What feed water is required?

On-site generators run on dissolved salt brine (typically 25–40 g/L) or seawater. Feed hardness should be controlled, because calcium and magnesium scale on the electrode surface, raise cell voltage and shorten life. Softened water is recommended for drinking-water duty.

How long do the electrodes last?

Electrode life depends on coating chemistry, loading, current density, brine quality and duty cycle. We verify performance with accelerated life testing per NACE TM0108-2008 in the chloride media of your application and confirm the design life per order — it is not stated as a fixed universal figure.

How is scaling controlled?

Periodic acid cleaning of the cell removes carbonate scale built up from hard feed water. We size the electrode gap and recommend cleaning intervals for your hardness, and can supply acid-wash tolerant coating systems where the duty requires them.

Is hydrogen produced during electrolysis?

Yes — hydrogen is evolved at the cathode during brine electrolysis. Generator systems include gas separation, venting and ventilation provisions so hydrogen concentration stays well below the lower explosive limit. This is standard engineering on every system we quote.

What strength of hypochlorite does the system produce?

Typical on-site output is a low-strength solution around 3–4.5 g/L equivalent free chlorine, produced continuously and dosed as generated. The exact strength is set by brine concentration, current and flow, and is confirmed per order.

Can you supply replacement electrodes for existing cells or pools?

Yes. Send the cell dimensions, connection arrangement and the original operating data, and we will fabricate Ru-Ir MMO electrodes as drop-in replacements with the same format and rating, including pool chlorinator electrode sets.

What is the lead time and what documents ship with the order?

Standard electrodes typically ship in 2–4 weeks depending on format and loading; complete systems are scheduled against your project. Each order ships with MTC, coating report, XRF data, ALT data, inspection record and certificate of conformity.

System Anatomy

The Components of an On-Site Generation System

Reliable hypochlorite output is a system result — brine preparation, electrolytic cell, rectifier, gas handling and control must work together. Ehisen supplies the coated electrodes and the cell engineering at the heart of the current path.

Brine Preparation

Salt is dissolved and filtered to the target concentration, and hardness is managed before the brine enters the cell — feed quality directly controls electrode life.

Electrolytic Cell & Electrodes

The Ru-Ir MMO coated titanium electrodes where chlorine evolution happens. Electrode gap, format and coating loading are sized to the cell current and output target.

Rectifier & Power Feed

Rectifiers supply stable, low-ripple DC to the cell. Clean current keeps chlorine output even and protects electrode coating life.

Gas Separation & Venting

Hydrogen from the cathode is separated, diluted and vented safely, and hypochlorite solution flows to storage. Ventilation provisions keep gas concentration below the lower explosive limit.

Dosing & Storage

Produced hypochlorite is stored in a day tank and dosed proportionally to flow or demand. Fresh, stable-strength disinfectant keeps dosing accurate.

Control & Monitoring

PLC or relay control manages brine flow, cell current, output and alarms. Cell voltage tracking gives an early signal of electrode ageing and scaling.

Project Sequence

From Water Chemistry to Commissioned System

Building or retrofitting an on-site chlorination plant follows a proven four-stage sequence. Ehisen supports you at every stage with engineering input and documented hardware.

Step 1

Water Analysis

Feed water chemistry, hardness, flow, dosing target and duty profile are reviewed, then chlorine output, cell size and electrode format are calculated.

Step 2

Engineering & Sample

We recommend the electrode system and can supply sample electrodes for testing in your actual feed water before full production.

Step 3

Fabrication & QC

Electrodes and cells are manufactured with batch traceability, coating inspection and accelerated life testing, with full process records shipped alongside.

Step 4

Installation & Trial Run

Cell, rectifier and dosing are commissioned, output and strength are verified, and cell voltage is recorded as the baseline for future electrode service.

Engineering tips: keep brine hardness and concentration stable, avoid over-current transients, and log cell voltage per week — a steady rise in cell voltage is the early sign of scaling or coating ageing, and scheduling acid wash before it accelerates will extend electrode life.

Need a Sodium Hypochlorite Generator for Your Site?

Send us your feed water chemistry, chlorine demand and duty profile — our engineers will recommend the generator, electrode format and coating rating within 24 hours.

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Explore More Titanium Electrode Products

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