At ppb levels, any air ingress can dominate the signal.
ABB Continuous Water Analysis
Dissolved oxygen
From aeration control in wastewater to corrosion monitoring in the steam and water cycle. At lower measuring ranges, sample conditioning and line integrity become part of the measurement.
From mg/L to sub-ppb
ADS420 · Navigator 500 · AeroStar
ADS420 provides optical DO measurement for wastewater and process water. Navigator ADS550 covers high-purity applications with a dedicated wet section. The new AeroStar Ultra ADS560 measures down to approximately 4 ppb, while AeroStar Ultra Trace ADS565 reaches approximately 0.8 ppb.
0–50 mg/LADS420
24-month cap lifeADS420
4 ppbADS560
0.8 ppbADS565
When to use it / when to consider alternatives
Practical guidance
A good fit when
- ADS420 for aeration basins, wastewater and process water
- Navigator/AeroStar for high-purity water and the steam cycle
- AeroStar for ppb/sub-ppb measurement
- optical technology to reduce consumables and drift
Consider carefully when
- air ingress into sample lines for trace DO measurement
- bubbles in the flow cell
- hot or pressurised samples outside the specification
- using an mg/L sensor to verify sub-ppb levels
Best practice
Installation and maintenance
In power applications, cool the sample to a suitable, stable temperature before analysis.
High-purity wet sections require stabilised and monitored flow.
Degassing, valves and pressure drops can produce bubbles and falsely high readings.
The ADS420 sensing cap is a long-life consumable; replace it according to diagnostics and the maintenance schedule.
Verify response time including sample transport delay, not just the sensor response.
SWAS/SCS integration
For high-pressure or high-temperature sampling points, we can integrate sample conditioning, cooling, pressure reduction, flow control and the analyser on the same panel.
Explore integrationBest to know
Useful technical details
ADS420
ABB specifies T90 <45 s at 25 °C, no minimum measurement flow requirement and a 24-month cap life.
AeroStar
Optical luminescence-quenching technology is intended for stability and low maintenance in ultrapure water.
Trace measurement
Moving from mg/L to ppb involves more than changing the range: tubing, fittings, drains and sample conditioning must be designed to prevent oxygen ingress.
SWAS
For DO measurement, Geyser can integrate the wet section, cooling, flow control and valves directly onto a panel.
AeroStar Ultra / Ultra Trace
New optical platform for power, process steam, semiconductor and high-purity applications where trace oxygen and corrosion control are critical.
Navigator ADS550
High-purity wet section using the Navigator 500 architecture; several wet sections can be connected to a common transmitter.
Models and installed base
Models we support
ADS420ADS550ADS560ADS565AeroStar UltraAeroStar Ultra Trace
ABB documentation
ABB datasheets and manuals
Download the documents for your model. Shared manuals, protocols and versions are identified in each document card.
ADS420
Optical dissolved oxygen sensor.
AeroStar Ultra ADS560 / Ultra Trace ADS565
Shared ADS56X documentation for the two measurement levels.
Navigator 500 · ADS550
Documentation for the Navigator analyser with ADS550 wet section and Navigator transmitter.
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Dissolved oxygen
Technical FAQ
Frequently asked questions
ADS420 or AeroStar?
ADS420 covers mg/L measurement in aeration and wastewater. AeroStar ADS560/565 is designed for high-purity water and trace DO at ppb/sub-ppb levels.
Does ADS420 need periodic calibration?
ABB describes it as a drift-free optical sensor requiring no routine calibration. Cap condition, cleaning and measurement plausibility must still be checked.
Why is ultra-trace DO much harder to measure?
At ppb levels, slight air ingress, permeable tubing, sample leaks or degassing can affect the reading more than the process itself.
Does the ADS420 optical sensor need flow?
ABB specifies no minimum flow requirement for the measurement principle, but the installation must still provide a representative sample without bubbles.
Where is DO measured in the steam and water cycle?
In condensate, feedwater and cycle points where oxygen affects corrosion and chemistry control; sample conditioning is essential.