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Submersible Optical Dissolved Oxygen Transmitter

Fluorescent optical dissolved oxygen transmitter OD8325

The OD8325 is a submersible dissolved oxygen sensor, complete with integrated electronics, to provide an industry standard 4-20mA output corresponding to the concentration of dissolved oxygen or the percentage saturation.

4-20mA Submersible Dissolved Oxygen Transmitter

The OD8325 is a fluorescent optical dissolved oxygen transmitter. Using a specially coated fluorescent layer, we can accurately measure the dissolved oxygen content of a solution by the way in which it interacts with various wavelengths of light.

The measured dissolved oxygen is not consumed by using this method (unlike with Polarographic or Clarke type Sensors) and it is not dependant upon a constant flow of solution.

Designed to IP68 specification with a rear mounting 2" threaded connection, the OD8325 easily connects to our riser tube, allowing the probe to be continually submersed into a steam, pit or a vessel, to provide continual dissolved oxygen measurements.

The 4-20mA output signal from the OD8325 is isolated to 600Ω and is suitable for directly connecting to PLC, online Data Logger, digital Chart Recorder or a 4-20mA controller such as our BC7635.

As a loop powered device the OD8325 is powered from the same 2 wires that also send out the 4-20mA signal to a receiving device, which makes the OD8325 incredibly simple to ingrate with PLC's and other control equipment.

Optical Dissolved Oxygen Measuring Ranges

The OD8325 is able to measure the following parameters:-

  • Dissolved Oxygen Saturation with range 0-200.0%
  • Dissolved Oxygen Concentration with range  0-20.00ppm

Using integrated temperature measuring devices, the OD8325 automatically compensates for temperature when providing the 4-20mA output signal.

Using a personal computer with a hyper-terminal client, the usr can interrogate the OD8325 and set secondary environmental parameters to compensate to the dissolved oxygen measurement. The secondary parameters are as follows:-

  • Pressure (mmHg) with range 500-800 mmHg
  • Salinity (Chloride) in ppm with range 0-60'000ppm
  • Relative Humidity (%) with range 0-100%

Using the hyper-terminal client, the zero point and sensitivity can be adjusted as well as the output 4-20mA current signal.

We can adjust any of the settings or the output measuring range at the factory, prior to the OD8325 being despatched.

Submersible Dissolved Oxygen Auto Clean Nozzle

The OD8325 is provided complete with an optional auto-clean nozzle. This allows a compatible compressed air device to be connected to the OD8325 to periodically remove any detritus or build up from the lens, to ensure constant operation. We strongly recommend that the air pressure does not exceed 3 Bar pressure. The typical cleaning period is 15 seconds, twice per day.  Alternative cleaning cycles can be used, dependant upon the nature of the application.

Submersible Dissolved Oxygen Transmitter Applications

The OD8325 is incredibly simple to install and integrate with measurement and control equipment. The OD8325 fluorescent technology provides a relatively maintenance free operation and offers exceptionally accurate dissolved oxygen measurements, even when a low level of dissolved oxygen concentration or saturation are present.

This makes the OD8325 ideal for use in water treatment and effluent treatment measuring applications. The OD8325 also lends itself to field mounting for environmental measurements. Considering the significance of dissolved oxygen on aquatic life, the OD8325 is often found in aquaculture for both leisure and farming applications.

OD8325 Features and Benefits

The OD8325 is a precision dissolved oxygen sensor, designed for permanent submersion into streams, open vessels, tanks or pits.  It provides a continuous dissolved oxygen measurement with an isolated 4-20mA output signal, proportional to either percentage saturation of dissolved oxygen, or the concentration of dissolved oxygen in ppm.

The OD8325 uses the fluorescent principle of measuring dissolved oxygen which offers significant advantages over the polarographic membrane or Clarke type sensors.  Most notably, the dissolved oxygen is not consumed as it is measured, and that a constant flow rate is not required to provide an accurate measurement.

The OD8325 is manufactured in PVC and is powered from the same two wires that receive the 4-20mA current signal.

OD8325 Submersible Dissolved Oxygen Transmitter Specifications

  • Specifications


    Optical Fluorescent Dissolved Oxygen Transmitter

    Model No:- OD8325

    Dissolved Oxygen Satuation Range:- 0-200.0%

    Dissolved Oxygen Saturation Resolution:- 0.1%

    Dissolved Oxygen Concentration Range:- 0-20.00 mg/L

    Dissolved Oxygen Concentration Resolution:- 0.01 mg/L

    Temperature Compensation Range:- 0.0-50.0°C

    Temperature Resolution:- 0.1°C

    Dissolved Oxygen Auto Temp Comp (ATC):- Via Automatic Lookup Table

    Repeatability Dissolved Oxygen:- ±0.5% of Dissolved Oxygen Scale.

    Dissovled Oxygen Response Time:- 95% : < 60 seconds

    Operating temperature:- 0-50ºC

    Operating Pressure:- 1 Bar

    Mounting Connection:- 2" thread (male)

    Autoclean Connection I/D:- 1/4"

    Autoclean Connection O/D:- 3/8" external

    Autoclean Max Pressure:- 3 bar max (for max 60 seconds)

    Power supply:- 9 / 36 VDC

    Weight:- 1060 grams

  • Features


    • Submersible Dissolved Oxygen Sensor for permanent installation into streams, pits, weirs and tanks.
    • Optical Fluorescent type dissolved oxygen sensor - dissolved oxygen is not consumed by the measuring device and a constant flow rate is not required for accurate DO2 measurements.
    • Simple to install and connect to measurement and control equipment - the 4-20mA current output is loop powered, meaning that the same two wires that transmit the signal also transmit the measurement signal.
    • The OD8325 has no moving parts and requires minimal periodic calibration and maintenance.
    • Factory set or configurable via computer - the OD8325 can be set with barometric pressure measurements, salinity measurements and relative humidity for precision readings even in challenging environmental conditions.
    • The OD8325 includes an auto-clean nozzle as standard. When working in environments where the lens may become fouled, an appropriate clean air system can remove any detritus or buildup and ensure minimal himan interaction with the optical dissolved oxygen sensor.
  • Data Sheets

    Data Sheets


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