Electrochemical chlorine dioxide sensor AS3

for water treatmentfor process measurementdigital

Product overview
German-made amperometric chlorine dioxide sensor AS3 for accurate ClO2 monitoring in drinking and hot water up to 70 °C. The sensor uses a potentiostatic three-electrode system to provide stable, long-term measurement signals for disinfection control. Outputs include analog (voltage / 4-20 mA), digitally processed analog and Modbus RTU digital output. Integrated automatic temperature compensation (0–70 °C) and optional automatic electrode cleaning (RV1) reduce maintenance needs. Robust materials (PEEK) and IP-rated connectors enable use in high-temperature or aggressive water treatment environments.

Key functionalities and interfaces
• Potentiostatic three-electrode operation system
• Outputs: analog (voltage / 4-20 mA), digitally processed analog, Modbus RTU digital output
• Integrated automatic temperature compensation (0–70 °C)
• Optional automatic electrode cleaning (RV1) to reduce maintenance

Special features

• Suitable for high water temperatures
• Suitable for high pressures
• Short response time
• Tolerates surfactants
• Reduced maintenance due to optional automatic electrode cleaning (RV1)

Applications
Monitoring chlorine dioxide and disinfectants in drinking water, hot water systems and general water treatment processes operating at elevated temperatures or in aggressive conditions.

Ambient and operational notes

• Stable pH recommended for reliable operation
• Measuring water temperature range up to 70 °C (no ice crystals in the measuring water)
• Ambient temperature range: 0 … +55 °C
• Max. allowed working pressure: 8 bar (observe installation and retaining ring requirements)

Technical Specification
Measurement parameter: Chlorine dioxide / free chlorine (amperometric)
Measuring ranges / resolution: 0.005…2.000 ppm: 0.001 ppm; 0.03…20.00 ppm: 0.01 ppm; 0.5…200.0 ppm: 0.1 ppm; additional ranges: 0.003…1.000 ppm: 0.001 ppm; 0.003…2.000 ppm: 0.001 ppm; 0.03…5.00 ppm: 0.01 ppm; 0.03…10.00 ppm: 0.01 ppm
Response time: T90 ≈ 30 s
Measuring water temperature: 0 … +70 °C (no ice crystals in the measuring water)
Ambient temperature: 0 … +55 °C
Temperature compensation: Automatic via integrated sensor, response time t90 ≈ 10 min. Max. permissible temperature change: 30 °C per hour; avoid sudden temperature shocks
Max. allowed working pressure: With retaining ring in FLC: -0.5 bar (no pressure impulses/vibrations); With retaining ring in FLC: -8 bar (no pressure surges/vibrations)
Flow rate (face velocity): Without RV1: min. 15 l/h; With RV1: 45–90 l/h
pH range: pH 1 – pH 12 (until ClO2 decomposition begins at/above pH 12)
Run-in time: First start-up approx. 1 hour up to 2 days depending on water quality
Zero point adjustment: Not necessary
Protection class: 5‑pole M12 plug-on flange: IP68; 2‑pole terminal with mA hood: IP65
Material: PEEK

Technical specifications

• Model: AS3
• Measurement parameter: Chlorine dioxide / free chlorine (amperometric)
• Measured water temperature range: 0 … +70 °C
• Ambient temperature: 0 … +55 °C
• Max. allowed pressure: 8 bar (with retaining ring; follow installation notes regarding pressure surges/vibrations)
• Response time (sensor): T90 ≈ 30 s
• Temperature compensation: Automatic (integrated sensor), t90 ≈ 10 min
• Flow rate requirements: min. 15 l/h (without RV1), 45–90 l/h (with RV1)
• pH operating range: pH 1 – pH 12
• Protection class: IP68 (5‑pole M12), IP65 (2‑pole terminal with mA hood)
• Housing/material: PEEK