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Optical luminescent devices which are extremely resistant to abrasion, extremely stable, and have greatly reduced maintenance and whole life costs.

Dissolved Oxygen Sensor


Key Features

  • No chemical or moving parts
  • Optional self-cleaning sensor and self-verification
  • Stable and reliable, perfect for process control
  • Suitable for all Dissolved Oxygen applications
  • Up to 36 months between DO meter maintenance
  • Up to 36 months between DO meter calibration


The ORAKEL range of online Dissolved Oxygen (DO) meters are optical luminescent devices which are extremely resistant to abrasion, extremely stable, and have greatly reduced maintenance and whole life costs.

How it Works

The sensing element (lumiphore) is activated, or excited when illuminated with a blue light. When activated, the lumiphore then emits blue light in an intensity that is inversely proportional to the amount of oxygen present in the water.



Lumiphore Optical Dissolved Oxygen

Dissolved Oxygen

0-50mg/l or 0-200% Saturation


Accuracy and Precision
±0.1mg/l from 0-8mg/l (1.25%) and ±0.2mg/l from 8-20mg/l

Better than 1% per month (without calibration)

Temperature Range
>0 up to 50°c

pH Range
pH2 up to pH10

Salinity Range

Temperature Compensation
Automatically by an integrated thermistor

Permissible Overpressure
10 bar

Typical Response Limited

Response Time
T90<45s, T95

Zero-point Adjustment
Not necessary

Manual using water saturated air

Response Check
Automatic with optional autoclean

Material of Construction
PVC, silicone, polycarbonate, stainless steel

Diameter approx. 43.7mm OD, length 203mm

Maintenance intervals
Manual calibration 3-36 months, lumiphore change 24-48 months

The shorter of 24 months from the date of manufacture or 12 months from date of first use

High levels of hypochlorite

RDO® PRO-X Probe is a registered trademark of In Situ Inc. Boulder Colorado


The ORAKEL System offers automatic in situ sensor verification as an option. The Control Unit is able to reduce maintenance by automatically checking it’s sensor operation at user defined time intervals. Calibration on the In Situ sensor is normally required only once per annum so with the automatic sensor verification option and the self clean option the sensor may not need to be inspected at all for years!

Stable and reliable

The ORAKEL Dissolved Oxygen sensor includes a time delay between the peak emission of blue light and peak response of fluoresced red light. The amount of delay is inversely proportional to the amount of oxygen present. This time delay can be expressed as a phase shift between the wave patterns of incident blue light and the fluoresced red light. This is in turn reported by the electronics into a ppm or mg/l reading of Dissolved Oxygen.



The ORAKEL Dissolved Oxygen sensor has no chemicals or moving parts. It is stable and reliable making it excellent for process controls and is suitable for all Dissolved Ovygen applications.

For aeration lane blower control and oxidation ditch dissolved oxygen control, the ORAKEL Dissolved Oxygen sensor offers unrivalled performance.
Two sensors are available:

  • Submersion mounting
  • Ideal for unpressurised applications
  • Suitable up to depths of 210m (25°C)
  • Acetyl construction
  • 1¼” NPT mounting thread
  • T90 <45 seconds

  • Titanium construction
  • Flow cell mountable
  • T90 <45 seconds

Learn More

Download the latest information available on the Orakel.

Datasheets – EN
MMS D017 – ORAKEL control unit

Datenblätter – DE
MMS D029 – GmbH ORAKEL Control Unit

Watch our Predictive Data Monitoring Video here

Read More

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