Oxymax W COS41

Summary

Product identification

Oxymax W COS41: Potentiostatic amperometric two-electrode sensor.

Application

The sensor is designed for the continuous measurement of dissolved oxygen in various water management areas, including:

• Sewage treatment plants: For oxygen measurement and regulation in activated sludge basins to ensure efficient biological cleaning.
• Water monitoring: As an indicator of water quality in rivers, lakes, and seas.
• Water treatment: For status monitoring of drinking water, such as oxygen enrichment or corrosion protection.
• Fish farming: For oxygen measurement and regulation to optimize living and growth conditions for fish.

Benefits

• Maximum measurement accuracy with long maintenance intervals and intelligent sensor self-monitoring.
• Membrane-covered design provides high O₂ selectivity, minimum maintenance, and minimal calibration effort.

Measuring principle

Dissolved oxygen molecules diffuse through a membrane and are reduced to hydroxide ions (OH⁻) at the cathode. At the anode, silver is oxidized to silver ions (Ag⁺), forming a silver halide layer. A current proportional to the oxygen content flows between the electrodes. This current is converted by a transmitter and displayed as oxygen concentration (mg/l, ppm), saturation index (% SAT), or partial pressure (hPa).

Measuring system

A complete measuring system typically includes:

• Oxygen sensor (Oxymax W COS41)
• Transmitter (e.g., Liquisys M COM223/253)
• Special measuring cable
• Assembly (e.g., flow assembly COA250, immersion assembly CYA611, or retractable assembly COA451)

Optional components include a universal suspension assembly support, junction box VBM, and automatic spray cleaning system Chemoclean.

Input

• Measured variable: Dissolved oxygen
• Units: mg/l, ppm, % SAT, or hPa
• Measuring range (with Liquisys M COM 223/253-DX/DS):
  • 0.05 ... 20.00 mg/l (ppm)
  • 0.00 ... 200 % SAT
  • 0 ... 400 hPa

Wiring

The sensor can be connected directly to the transmitter using a special measuring cable. For cable extensions beyond the fixed cable length, a junction box VBM and the special measuring cable CYK71 are required.

Special measuring cable CYK71 assignments:

• Terminal S: Outer shield
• Terminal 12: Active inner shield (NTC)
• Terminal 90: Cathode
• Terminal 91: Anode
• Terminal 11: NTC temperature sensor

Performance characteristics

• Response time (T90): 3 minutes (at 20 °C / 68 °F)
• Response time (T99): 9 minutes (at 20 °C / 68 °F)
• Reference operating conditions: 25 °C (77 °F), 1013 hPa (15 psi)
• Signal current in air: approx. 300 nA
• Zero current: Zero current free
• Measured value resolution: 0.01 mg/l (0.01 ppm)
• Maximum measured error: ±1 % of measured value
• Long-term drift: < 1 % per month (with permanent polarization)
• Influence of medium pressure: Pressure compensation not necessary.
• Polarization time: < 60 minutes
• Oxygen intrinsic consumption: Approx. 90 ng/h in air at 25 °C (77 °F)

Installation

• Angle of installation: Permissible up to horizontal (0 ... 180°); overhead installation is not permitted.

Environment

• Ambient temperature range: –5 to 50 °C (20 to 120 °F)
• Storage temperature:
  • Filled with electrolyte: –5 to 50 °C (20 to 120 °F)
  • Without electrolyte: –20 to 60 °C (0 to 140 °F)
• Ingress protection:
  • Fixed cable versions: IP 68 (10 m / 33 ft water column at 25 °C / 77 °F in 30 days)
  • TOP68 plug-in head versions: IP 68 (1 m / 3.3 ft water column at 50 °C / 122 °F in 7 days)

Process

• Process temperature: –5 to 50 °C (20 to 120 °F)
• Process pressure: max. 10 bar (145 psi) permissible overpressure. Underpressure operation is not permissible.

Mechanical construction

• Weight:
  • With cable length 7 m / 23 ft: 0.7 kg / 1.5 lbs.
  • With cable length 15 m / 49 ft: 1.1 kg / 2.4 lbs.
  • With TOP68 plug-in connection: 0.3 kg / 0.66 lbs.
• Material:
  • Sensor shaft: POM
  • Membrane cap: POM
  • Cathode: Gold
  • Anode/Reference electrode: Silver / silver bromide
• Process connection: G1 and NPT ¾"
• Maximum cable length: 50 m (164 ft)
• Membrane thickness: approx. 50 μm
• Electrolyte: Alkaline electrolyte

Scope of delivery

• Oxygen sensor with transport protection cap
• Accessories set: 2 replacement membrane caps, 10 electrolyte ampoules, 1 sealing kit (3 O-rings), 6 abrasive sheets.
• Operating Instructions (CD)
• Brief Operating Instructions (paper)

Accessories

• Assemblies: Flow assembly COA250, Immersion assembly Dipfit W CYA611.
• Zero solution: For producing oxygen-free solution.
• Measuring cable: COK41 (for TOP68 plug-in head), CYK71 (non-terminated, sold by the meter).
• Junction box: VBM (IP 65, aluminum).
• Transmitter: Liquisys M COM 223/253.

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Disclaimer: This extraction may miss figures, footnotes, or revisions. Contractual data must match the OEM PDF revision used on the project.

Official datasheet (PDF)

Lenntech datasheet mirror