How to select an online chlorine analyzer
Begin with the exact disinfectant and reported value, then compare measurement method, sample conditions and maintenance.
The selection in one paragraph
First specify free chlorine, total chlorine, combined chlorine, chlorine dioxide or active chlorine. Then confirm range, pH, conductivity, temperature, sample flow, pressure, expected maintenance and whether the project permits reagents.
Confirm these conditions before choosing a model.
Free, total or another disinfectant?
Do not use the word chlorine alone. State exactly what the process or regulation requires.
Reagent-based or electrochemical?
DPD colorimetry and amperometric or membrane methods have different operating conditions and maintenance.
Is sample pH stable?
Some electrochemical methods have a defined pH operating window or pH dependence.
Is the water sufficiently conductive?
Certain amperometric sensors state minimum conductivity requirements and are not suitable for ultra-pure water.
What flow and pressure are available?
Flow cell, pressure regulation and drain conditions must match the selected method.
Can the site handle reagents or membrane service?
Choose the method the operator can sustain, not just the lowest purchase price.
Compare common online chlorine methods
Define the measurand before the model
Free chlorine, total chlorine, combined chlorine and chlorine dioxide are not interchangeable. A project should state both the disinfectant and the reporting basis before a sensor or analyzer is selected.
Water conditions also determine whether an electrochemical method is appropriate. DPD systems are often chosen when a colorimetric method is required, while reagent-free electrochemical systems can reduce consumables when the matrix is suitable.
RFQ checklist
Include enough sample information to choose the method and flow-cell arrangement.
- Disinfectant and required reported value
- Normal, low and peak concentration
- pH, conductivity and temperature
- Sample pressure and available flow
- Reagent policy and maintenance capability
- Calibration or verification procedure
- Power, outputs, relays and communications
Products to compare after the duty is defined.
Free / Total Chlorine DPD Analyzer
A reagent-based colorimetric option for free and total chlorine duties.
View technical data↗Free / Total Chlorine and Chlorine Dioxide Analyzer
A membrane-based digital configuration for multiple disinfectant duties.
View technical data↗Free Chlorine / Chlorine Dioxide Analyzer
A microelectronic MEMS configuration for suitable water and flow-cell conditions.
View technical data↗Real residual and total chlorine projects
See drinking-water and secondary-supply applications with English project background and installed equipment.
Questions buyers ask before quotation.
What is the difference between free and total chlorine?+
Free chlorine is the available disinfecting chlorine species; total chlorine includes free chlorine plus combined chlorine. The analyzer must match the required reported value.
When should I choose a DPD chlorine analyzer?+
Choose DPD when a reagent-based colorimetric method is required or preferred and the site can support reagent replacement, sample flow and waste handling.
Can a reagent-free chlorine sensor work in every water source?+
No. Confirm pH, conductivity, temperature, pressure, flow and disinfectant chemistry for the exact sensor method before selection.