Membrane vs Membrane-Free Chlorine Sensors
Amperometric chlorine sensors measure an electrochemical current associated with disinfectant at the electrode. Membrane designs use a selective barrier and internal electrolyte; membrane-free designs expose the sensing surfaces to water. Both can avoid continuous DPD reagent dosing, but reagent-free does not automatically mean maintenance-free or drain-free.
How does an amperometric chlorine sensor work without reagents?
An electrochemical reaction at the sensing electrode creates a current that the instrument relates to concentration through its measurement design and calibration. Online DPD analyzers instead add reagents and measure the resulting color.
Some reagentless sensors still need an electrolyte refill or membrane replacement. Those consumables have a different role from continuously dosed colorimetric reagents. Confirm what the manufacturer includes in the term reagent-free.
Compare the whole installation
Membranes can help control transport to the electrode, but require model-specific care. Bare electrodes avoid the membrane and may use mechanical cleaning to manage deposits. Neither design should be assumed immune to interference or maintenance.
Compare pH and temperature limits, required approach flow, sample conditioning, response time and reference verification. Direct in-pipe suitability also depends on potable-water contact certification and the qualified mounting assembly.
Reagentless chlorine sensor maintenance cost
Budget for reagents where applicable, membranes, electrolyte, cleaning parts, reference checks, labor, sample water and disposal. Use current quotations and your own service history. A single annual parts price is not a total cost of ownership.
Compare the original Hach CL17 and CL17sc separately. For YSI FCML, ProMinent, Walchem and Endress+Hauser Memosens, identify the exact sensor, controller and flow assembly before comparing specifications or calibration steps. Product families can include different analytes and ranges.
Sources and supporting documentation
Manufacturer instructions govern model-specific service. Calculated scenarios are identified separately from published specifications.