At low ranges, even microbubbles can dominate the signal.
ABB Continuous Water Analysis
Turbidity and TSS
From drinking water filtration to solids control in wastewater. Low-range NTU measurement and TSS measurement in heavily loaded samples require different approaches.
Turbidity + TSS
ATS430 / low-range 4690
ATS430 measures turbidity/TSS using 90° scattered light in accordance with ISO 7027, with a specified detection limit of 0.006 NTU. The 4690 specialises in low-range drinking water and filtration monitoring.
0.006 NTUATS430 detection limit
T90 <30 sATS430 without filtering
0–40 NTU4690 low range
ISO 7027Optical method
When to use it / when to consider alternatives
Practical guidance
A good fit when
- ATS430 for wastewater, sludge, process applications and TSS
- 4690 for drinking water and low-range filtration monitoring
- flow-through installation for stable conditions and bubble control
- immersion where the sampling point is open and representative
Consider carefully when
- unmanaged bubbles or degassing
- dirty optics without a cleaning strategy
- NTU-to-TSS conversion without sample correlation
- sensors mounted close to aeration or intense agitation
Best practice
Installation and maintenance
Coating on the window can be indistinguishable from an actual increase in turbidity.
Avoid excessive flow changes that alter the bubbles or solids present in the cell.
Use standards and procedures appropriate to the method and range.
Correlate mg/L readings with laboratory results for the actual matrix, especially if the solids change.
Avoid walls, the bottom, foam and unrepresentative settling zones.
Best to know
Useful technical details
ATS430
Measures turbidity and TSS; ABB specifies metal versions up to 10 bar and 0–60 °C.
4690
Automatic optical cleaning, bubble rejection and dry-standard verification are intended for low-range drinking water applications.
TSS
This is a site-specific application: the optics measure scattering, not mass directly.
AWT platform
ATS430 can be integrated with AWT420/AWT424, including diagnostics and communications.
Models and installed base
Models we support
ATS430ATS410 / 4690AWT420AWT424
ABB documentation
ABB datasheets and manuals
Download the documents for your model. Shared manuals, protocols and versions are identified in each document card.
ATS430
Turbidity and suspended solids. English datasheet and Italian/English manuals.
ATS410 · low turbidity
Dedicated documentation for the ATS410 sensor. It is not presented as the manual for the previous 4690 transmitter.
Request a quotation
Turbidity and TSS
Technical FAQ
Frequently asked questions
Does ATS430 also measure TSS?
Yes. ABB offers it for turbidity and total suspended solids, but the TSS correlation depends on the sample and must be calibrated for the actual matrix.
ATS430 or 4690/ATS410?
ATS430 is versatile for wastewater, process applications and TSS; 4690 specialises in low-range drinking water and filtration performance.
Why do bubbles affect turbidity?
Bubbles scatter light just like particles. A suitable flow cell and effective bubble management are therefore essential.
What does ISO 7027 mean?
It defines nephelometric measurement using a near-infrared source and standardised geometry; ATS430 uses 90° scattered light in accordance with ISO 7027.
Can NTU be automatically converted to mg/L TSS?
There is no universal conversion. The relationship depends on particle size, shape and refractive index, and must be correlated with actual samples.