China Residual Chlorine Meter Tester Suppliers & Factory

Free Chlorine refers to dissolved aqueous hypochlorous acid (HOCl) and hypochlorite ions (OCl⁻), which represent the unreacted, highly active disinfection agents available to inactivate biological pathogens instantly. Combined Chlorine occurs when free chlorine reacts with nitrogen compounds (such as ammonia or organic amines) to synthesize chloramines (monochloramine, dichloramine, trichloramine), which possess significantly slower germicidal kinetics and generate strong odors. Total Chlorine is the algebraic sum of Free Chlorine and Combined Chlorine. BOQU manufactures dedicated amperometric testers for free chlorine as well as total residual oxidant (TRO) meters for complete disinfectant accounting.

Amperometric sensors primarily react to HOCl molecules, which readily diffuse across the boundary layer and reduce at the cathode. At pH 6.5, roughly 90% of free chlorine exists as HOCl; however, at pH 7.5, HOCl drops to approximately 50%, and at pH 8.5, less than 10% remains as HOCl (the remainder having dissociated into the less reactive OCl⁻ ion). If a meter measures only the electrochemical current without simultaneously measuring process pH, an increase in pH will cause the meter to report a false "loss" of chlorine, triggering dangerous over-dosing of chemical feed pumps. BOQU online analyzers utilize integrated glass pH electrodes to compute true active free chlorine in real time.

Because electrochemical amperometric sensors consume a minute quantity of hypochlorous acid at the platinum working cathode during measurement, they rely on a consistent flow velocity (typically 30 to 60 L/h) to maintain a steady diffusion layer thickness. If line pressure fluctuates, diffusion dynamics shift, creating artificial signal instability. BOQU's specialized acrylic constant-head flow cell utilizes an overflow weir design: excess supply water spills over an internal baffle into an atmospheric drain, maintaining an absolutely invariant hydraulic head and constant flow velocity across the sensor face.

Initial commissioning requires an electrical or chemical zero calibration using dechlorinated water (passed through an activated carbon filter) and a slope (span) calibration. The slope is calibrated in situ by sampling the analyzer effluent and conducting a comparative laboratory DPD colorimetric test (standard method 4500-Cl G). Thanks to the solid platinum cathode and pressurized reference chemistry, routine slope verification is typically required only once every 30 to 60 days in clean municipal potable applications, and every 14 days in heavily loaded industrial cooling towers.

Shanghai BOQU Instrument Co., Ltd. is an authentic original equipment manufacturer founded in Shanghai in 2007. We operate 4,632 m² of proprietary production, calibration, and R&D space across two specialized facilities (Kangqiao Industrial Zone and Lingang Free Trade Area), employing over 200 professionals. Overseas procurement officers and technical auditors are welcome to inspect our production lines directly or utilize our 360-degree interactive virtual tour.

Yes. Every BOQU controller is standard-equipped with galvanic isolated 4-20mA current loops (up to 750Ω load capacity) and an RS485 communication port running industry-standard Modbus RTU protocol (standard baud rates selectable up to 115200 bps). In addition, our all-in-one digital IoT sensors can bypass controllers entirely, connecting directly to PLC analog/digital input cards or remote telemetry units (RTUs), which drastically lowers panel hardware investment.

Every export shipment includes an individualized Certificate of Calibration and Inspection, ISO 9001/14001 conformity certification, CE declaration of conformity, comprehensive English engineering installation manuals, and Certificate of Origin (CO/Form E/Form A upon request for tariff reduction). Optional material test reports (EN 10204 3.1) and third-party audit reports from SGS or TÜV are available for major EPC engineering contracts.