1 applications, 2 turbidity units, Applications – Campbell Scientific OBS500 Smart Turbidity Meter with ClearSensor Technology User Manual
Page 19: Turbidity units
OBS500 Smart Turbidity Meter with ClearSensor™ Technology
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Insensitivity to bubbles and organic matter
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Ambient-light rejection
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Low temperature coefficient
Side scatter sensors have the following advantages:
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More accurate in very clean water
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Fixed measurement volume
5.1 Applications
Turbidity sensors are used for a wide variety of monitoring tasks in riverine,
oceanic, laboratory, and industrial settings. They can be integrated in water-
quality monitoring systems, CTDs, laboratory instrumentation, and sediment-
transport monitors. The electronics of the OBS500 are housed in a Delrin
package, which is ideal for salt water or other harsh environments.
Applications include:
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Compliance with permits, water-quality guidelines, and regulations
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Determination of transport and fate of particles and associated
contaminants in aquatic systems
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Conservation, protection, and restoration of surface waters
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Assess the effect of land-use management on water quality
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Monitor waterside construction, mining, and dredging operations
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Characterization of wastewater and energy-production effluents
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Tracking water-well completion including development and use
5.2 Turbidity Units
Conceptually, turbidity is a numerical expression in turbidity units (TU) of the
optical properties that cause water to appear hazy or cloudy as a result of light
scattering and absorption by suspended matter. Operationally, a TU value is
interpolated from neighboring light-scattering measurements made on
calibration standards such as Formazin, StablCal, or SDVB beads. Turbidity is
caused by suspended and dissolved matter such as sediment, plankton, bacteria,
viruses, and organic and inorganic dyes. In general, as the concentration of
suspended matter in water increases, so will its turbidity; as the concentration
of dissolved, light-absorbing matter increases, turbidity will decrease.
Descriptions of the factors that affect turbidity are given in Section 8, Factors
that Affect Turbidity and Suspended-Sediment Measurements. Like all other
optical turbidity monitors, the response depends on the size, composition, and
shape of suspended particles. For this reason, for monitoring concentrations,
the sensor must be calibrated with suspended sediments from the waters to be
monitored. There is no “standard” turbidimeter design or universal formula for
converting TU values to physical units such as mg/l
or ppm. TU values have
no intrinsic physical, chemical, or biological significance. However, empirical
correlations between turbidity and environmental conditions, established
through field calibration, can be useful in water-quality investigations.
The USGS has an excellent chapter (6) on turbidity measurements in their
“National Field Manual for the Collection of Water-Quality Data”:
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