Optical measurement of dissolved oxygen and water temperature

ESKO12 – Optical Dissolved Oxygen Sensor

The ESKO12 sensor operates on the principle of measuring the intensity of radiation on the luminescent layer of the sensor’s measuring head, which is triggered by a short, high-energy light pulse generated by the sensor’s electronics. Oxygen atoms absorb the pulse energy that would otherwise be emitted as photons by the phosphor atoms; therefore, the concentration of dissolved oxygen in the measured solution is inversely proportional to the measured intensity of the luminescent radiation. The sensor also regularly measures the intensity of low-energy light reflected from the phosphor (which does not induce luminescence) and uses this measured value for the sensor’s self-calibration.

  • Luminescent optical method for measuring dissolved oxygen concentration
  • Accurate measurements without the need for regular calibration
  • The sensor does not consume oxygen during measurement, so it does not require water flow around the sensor
  • Both the ESKO12 rod-type sensor and the suspended sensor use the same S423/C/OPT sensor
  • Quick installation of the ESKO12 rod-type sensor in the correct position using the adjustable DE2 stainless steel bracket
  • Suspended sensor design with the S423/C/OPT sensor and a 10-meter cable
  • RS485 communication interface using the Modbus RTU protocol, compatible with FIEDLER units
  • Internal sensor for measuring water temperature
  • Wide supply voltage range from 10 to 24 V DC

Description

Optical sensors do not require regular calibration; there is no need to replace the electrolyte or chemically clean a worn anode, and they do not require the solution to flow around the measuring head, since they do not consume any oxygen atoms during measurement.
The sensors are placed in the measured medium at an angle (30 to 45 degrees) to prevent the accumulation of gases on the surface of the luminescent measuring head (the angle prevents the formation of air pockets near the phosphor). The ESKO12 sensor is available in a rod-mounted or suspended version.
The rod-mounted sensor can be easily installed using the DE2 bracket on the railing of the activation tank or on the edge of the tank. The DE2 bracket consists of two parts and, in addition to adjusting the angle, also allows the sensor to be moved within the bracket—for example, to accommodate the current water level or to clean the sensor of coarse debris.
The suspended sensor comes standard with a 10-meter cable fitted with a 5-pin M12/5F industrial connector at the end. When suspending the sensor by the cable, it is also necessary to ensure that the sensor is positioned at an angle so that air bubbles do not accumulate on the measuring head of the S423 sensor.

Applications

Continuous monitoring of oxygen concentrations in many areas of water management:
- Wastewater treatment plants
- Industrial production processes
- Monitoring of stream and river water
- Fisheries

Technical specifications

Technical Specifications ESKO12 - Optical Dissolved Oxygen Sensor
Measuring Range 0.00 to 20.00 mg/L
Measuring Method optical measurement of stimulated luminescence
Accuracy +/-0.1 mg/L
Response Time reaches 90% of the value in < 60 sec
Measurement Frequency min 1 measurement/sec
Operating temperature range -10 to +60 °C
Maximum operating pressure 5 bar
Dimensions (diameter x length) 40 x 1750 mm
Sensor material stainless steel, Tecaform
Diameter of the measuring head’s phosphor 10 mm
Weight of the rod sensor 2200 g
Weight of suspended sensor 1150 g
Cable length of suspended sensor 10 m, M12 connector
Supply voltage 12 to 24 V DC
Interface RS485, Modbus RTU protocol
Temperature compensation internal NTC
Protection rating IP68

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ESKO12 – Optical Dissolved Oxygen Sensor



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