Tech Insights

How to Choose a Chlorine Dioxide Sensor?

Oct 20, 2026

Chongqing YuanGan Technology offers two ClO₂ sensor families: membraneless (dual platinum, single platinum ring, self-cleaning) and membrane-covered. Both are three-electrode amperometric sensors and respond to chlorine dioxide in water. The difference is how the electrode meets the sample.

In short: High-purity ClO₂ → either membraneless or membrane-covered works. Composite ClO₂ (with residual-chlorine by-products) → prefer membrane-covered. Unsure? Check with a ClO₂ DPD kit plus glycine.

Membraneless vs membrane-covered

	Membraneless	Membrane-covered
How it measures	Electrode in direct contact with water	Selective permeable membrane over the electrode
Residual chlorine	Residual chlorine (e.g. hypochlorous acid) can also react at the electrode and inflate the reading	With the internal electrolyte, the membrane mainly passes ClO₂ and blocks residual chlorine
Best fit	High-purity ClO₂, low residual-chlorine interference	Composite ClO₂ with substantial residual-chlorine by-products

Selection is driven by disinfectant feedstock type, not by price or “whether it has a membrane.”

Choose by disinfectant type

High-purity chlorine dioxide

Either sensor type is acceptable.

Composite chlorine dioxide (typically sodium chlorate + acid)

The reaction yields ClO₂ plus substantial residual-chlorine by-products (chlorine gas, hypochlorous acid, and related species). A membraneless sensor can count those species and read high. A membrane-covered sensor is strongly recommended for clearer anti-interference performance and more realistic ClO₂ readings.

If you do not know the disinfectant type

Use a ClO₂ DPD handheld kit that includes a residual-chlorine masking agent (glycine). Measure the same sample twice:

Without the masking agent
With the masking agent

Then compare:

Reading barely changes after masking → low residual-chlorine interference → treat as high-purity; either sensor type is fine
Reading drops significantly after masking → high residual-chlorine interference → treat as composite; prefer membrane-covered

Tips for membrane-covered sensors

Flow: Flow-sensitive — keep the flow cell within the required range
Polarization: After moving, cleaning, maintaining, or powering up, wait until the sensor polarizes and stabilizes before reading or calibrating
Calibration: Calibrate regularly; long gaps cause drift
Continuous disinfectant: Keep disinfectant present in the sample (recommended > 0.1 mg/L); otherwise the membrane head can foul with bacteria and clog