Campbell Scientific OBS-3+ and OBS300 Suspended Solids and Turbidity Monitors - Manual (Page 15)

OBS-3+ and OBS300 Suspended Solids and Turbidity Monitors
8. If LoggerNet, PC400, or PC200W is running on your PC, and the PC to
datalogger connection is active, you can click Finish in Short Cut and you
will be prompted to send the program just created to the datalogger.
9. If the sensor is connected to the datalogger, as shown in the wiring
diagram in step 6, check the output of the sensor in the datalogger support
software data display to make sure it is making reasonable measurements.
5. Overview
The heart of an OBS ® sensor is a near infrared (NIR) laser and photodiode for
detecting the intensity of light scattered from suspended particles in water.
Electrical connections are made with a molded-cable assembly terminated with
an MCIL wet-pluggable underwater connector. With its unique optical design
(U.S. Patent No. 4,841,157), OBS sensors perform better than most in situ
turbidity monitors in the following ways:
• Small size and low power
• Highly linear response
• Insensitivity to bubbles and organic matter
• Ambient-light rejection and low temperature coefficient
5.1 Applications
OBS 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 applications include:
• Compliance with permits, water-quality guidelines, and regulations
• Determination of transport and fate of particles and associated
contaminants in aquatic systems
• Conservation, protection and restoration of surface waters
• Assess performance of water and land-use management
• Monitor waterside construction, mining, and dredging operations
• Characterization of wastewater and energy-production effluents
• Tracking water-well completion including development and use
5.2 Turbidity
Conceptually, turbidity is a numerical expression in turbidity units (NTU) 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 NTU
value is interpolated from neighboring light-scattering measurements made on
calibration standards such as Formazin, StablCal, or SDVB.
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