Oxymax COS61

Summary

Product identification

• Product Name: Oxymax COS61D/COS61
• Product Type: Optical sensor for measuring dissolved oxygen
• Technology: Digital optical sensor based on fluorescence quenching principle.
• Protocols: With or without Memosens protocol.
• Model Variants:
  • COS61D: Liquiline sensor, Memosens protocol, optionally with M12 plug.
  • COS61: Liquisys sensor, compatible with COM2x3W and COM2x3D (with conversion kit).

Application

• Wastewater treatment plants (activated sludge basin oxygen regulation, outlet monitoring)
• Water monitoring (rivers, lakes, seas for water quality indication)
• Water treatment (status monitoring, e.g., drinking water enrichment, corrosion protection)
• Fish farming (oxygen measurement and regulation for optimal conditions)

Key Features and Benefits

• Optical Technology: Minimum maintenance, maximum availability.
• Digital Signal Processing:
  • Calibration data saved in sensor.
  • High EMC protection via digital communication.
  • Extended maintenance intervals and long-term stability.
  • Intelligent self-monitoring.
• Measurement: No flow required, possible in still water.
• Plug & Play: Safe communication based on Memosens protocol (COS61D).
• Compatibility: COS61 is compatible with COS31 and COS41.

Measuring Principle

The sensor uses oxygen-sensitive molecules (markers) integrated into an optically active layer. The measurement process relies on fluorescence quenching:

1. Green light pulses are sent to the fluorescence layer.
2. Markers fluoresce with red light pulses.
3. The duration and intensity of the red light pulses are dependent on the oxygen content. Higher oxygen levels mask markers, resulting in shorter and less intense signals.

Measurement Parameters

• Measured Variables: Dissolved oxygen.
• Units: mg/l, µg/l, ppm, ppb, %SAT, or hPa.
• Compensation: Medium temperature is automatically recorded. Air pressure can be set statically or entered via an additional sensor.

Operating Limits

• Measuring Ranges (with Liquiline CM44x or Liquisys COM2x3-W):

  • 0 to 20 mg/l
  • 0 to 400 hPa
  • 0 to 200 % SAT (These ranges apply for 20 °C and 1013 hPa)

• Process Temperature: -5 to +60 °C (20 to 140 °F)

• Process Pressure: Ambient pressure 1 to 10 bar (14.5 to 145 psi) abs.

• Ambient Temperature: -20 to 60 °C (-4 to 140 °F) at 95% relative air humidity, non-condensing.

• Storage Temperature: -20 to 70 °C (-4 to 158 °F) at 95% relative air humidity, not condensing.

Electrical

• COS61D Connection: Fixed cable with terminated cores, or optional M12 plug. Connects directly to transmitter terminals or via M12 sensor socket.
• COS61 Connection: Fixed cable or TOP68 plug connection. Connects via SXP connector to field device or terminal connections for cabinet devices (e.g., Liquisys COM223).
• Maximum Cable Length: max. 100 m (330 ft), including extension.
• Interface:
  • COS61D: Memosens protocol.
  • COS61: RS 485.

Performance Characteristics

• Response Time (t90, from air to nitrogen at reference conditions): 60 s.
• Maximum Measured Error:
  • COS61D: < 12 mg/l: 0.01 mg/l or ±1% of reading; 12 mg/l to 20 mg/l: ±2% of reading.
  • COS61: < 12 mg/l: 0.02 mg/l or ±1% of reading; 12 mg/l to 20 mg/l: ±2% of reading.
• Repeatability: ±0.5% of end of measuring range.
• Operating Life of Sensor Cap: > 2 years (under reference conditions, protect from direct sunlight).

Mechanical / Hydraulic

• Degree of Protection:

  • COS61D: IP 68 (10 m water column, 25 °C, 30 days).
  • COS61 (Fixed cable): IP 68 (10 m water column, 25 °C, 30 days).
  • COS61 (Top68 plug): IP 68 (1 m water column, 50 °C, 7 days).

• Materials (Parts in contact with medium):

  • Sensor cap: PVC / POM
  • Fluorescence layer: Silicone
  • Orifice plate: PET
  • O-rings: EPDM
  • Pin holder: 1.4404
  • Shaft tube: 1.4571
  • Housing connection: POM
  • Protection guard: POM
  • Housing air purge unit: POM

• Process Connection:

  • COS61D: G1, NPT 3/4"
  • COS61: G1

• Weight:

  • With 7 m cable: 0.7 kg (1.5 lbs)
  • With 15 m cable: 1.1 kg (2.4 lbs)
  • With TOP68 plug: 0.3 kg (0.66 lbs) depending on version.

• Dimensions: See figures 12, 13, 14, 15, 16 in the original document.

Environment and Compatibility

• Electromagnetic Compatibility (EMC):

  • COS61D: EN 61326: 2005, Namur NE 21:2007.
  • COS61: EN 61326: 1997 / A1: 1998.

• Certificates and Approvals:

  • Declaration of Conformity (CE mark).
  • EAC (TP TC 004/2011, TP TC 020/2011).
  • CSA GP (Class 2 power supply, Overvoltage category I, max. height 2000 m).
  • CSAus NI Cl 1, Div 2 (Hazardous areas, specific installation requirements apply).
  • Explosion Protection: Class 1, Division 2, Groups A, B, C, D T6; IP67/IP68.

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Disclaimer: 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