YSI EXO Turbidity Sensor

YSI EXO Turbidity Sensor


The EXO turbidity sensor is a digital smart sensor featuring welded titanium construction and wet-mateable connectors.


  • 0 to 4000 FNU measurement range
  • T63<2 sec response time
  • 0.3 FNU or ±2% of reading accuracy from 0 to 999 FNU
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Turbidity is the indirect measurement of the suspended solid concentration in water and is typically determined by shining a light beam into the sample solution and then measuring the light that is scattered off of the particles which are present. The suspended solid concentration is an important water quality factor and is a fundamental measure of environmental change. The source of the suspended solids varies in nature (examples include silt, clay, sand, algae, organic matter) but all particles will impact the light transmittance and result in a turbidity signal.

The EXO Turbidity sensor employs a near-infrared light source and detects scattering at 90 degrees of the incident light beam. According to ASTM D7315 method, this type of turbidity sensor has been characterized as a nephelometric near-IR turbidimeter, non-ratiometric. This method calls for this sensor type to report values in formazin nephelometric units (FNU). FNU is the default calibration unit for the EXO sensor but users are able to change calibration units to nephelometric turbidity units (NTU), raw sensor signal (RAW), or total suspended solids (TSS) assuming the user enters the appropriate correlation data.

The RAW value is a value unaffected by user calibrations and provides a range from 0-100, representing the per cent of full scale that the sensor detects in a sample. While all turbidity sensors will read consistently in formazin, other calibration solutions and field readings will vary between different models of turbidity sensors. These differences are thought to be a result of differing optical components and geometries and the resulting detection of varying suspended sediment characteristics. This effect is inherent in the nature of every turbidity sensor, and as a result readings between different model turbidity sensors are likely to show different field values even after calibration in the same standards.

For long-term, in situ continuous monitoring of turbidity, the EXO2 sonde has a wiper to clean the turbidity sensor to avoid sensor fouling and maintain accuracy.

Image Part # Product Description Price Stock Order
YSI EXO Turbidity Sensor 599101-01 EXO turbidity sensor In Stock
Image Part # Product Description Price Stock Order
YSI Turbidity Standards 608000 6080 turbidity standard, 0 FNU (ProDSS & EXO); 0 NTU (6136), 1 gallon
Usually ships in 3-5 days
YSI Turbidity Standards 607200 6072 turbidity standard, 12.4 FNU (ProDSS & EXO); 12.7 NTU (6136), 1 gallon
Usually ships in 3-5 days
YSI Turbidity Standards 607300 6073G turbidity standard, 124 FNU (ProDSS & EXO); 126 NTU (6136), 1 gallon
Usually ships in 3-5 days
YSI Turbidity Standards 607400 6074 turbidity standard, 1010 FNU (ProDSS & EXO); 1000 NTU (6136), 1 gallon
In Stock
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Questions & Answers

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What benefits does this sensor have over my 6136 turbidity sensor?
The EXO turbidity sensor has an extended range meaning it can measure turbidity from 0 to 4000 FNU.
Does my EXO sensor maintain it's accuracy over 1000 FNU?
The EXO Sensor has an accuracy or +/-5% from 1000-4000 FNU.
Why does the EXO sensor use an internal thermistor?
The turbidity temperature effect is largely from the LED inside the turbidity probe. To accurately measure temperature compensation, the LED temperature should be measured rather than the water temperature.
Can I use my EXO sensor with my 6-series sonde?
EXO sensors are not backwards compatiable with 6-series sondes.

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