OBS-3+ sensor measures suspended solids and turbidity

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Sediment Instruments for all Environments

OBS-3+
New in 2005!

OBS-3+ information sheet (76 kb PDF)
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Features

Measures turbidity and suspended solids
Compact micro low-power probe
Integral Voltage clamp and 4-20 mA current loop

Applications

River and stream gauging
Add-on sensor for CTDs, data loggers, and current meters
Monitor dredging and mining operations
Permit compliance
Control water quality in settling ponds and tanks
Sediment transport research
Laboratory measurements

Description
The OBS®-3+ sensor measures suspended solids and turbidity by the optical backscatter method (ASTM 6677). It features a compact micro probe that responses almost linearly over a 1000-fold change in sediment concentration (SSC) and turbidity.

Ranges
Turbidity		0-2,000 NTU
SSC¹	Mud	0-2,500 mg/l
	Sand	0-50 g/l^-1
¹ Depends on sediment type.

Accuracy
Turbidity		0.25 NTU or 1% of reading ²
Concentration ¹	Mud	0.5 mg/l or 1% of reading ²
	Sand	0.25 g/l or 1% of reading ²
² whichever is larger.
Other Data
Maximum data rate
		10 Hz
Infrared wavelength		850 nm
Maximum depth		500 m
Drift		< 2% / year
Power		5 V / 10 mA
Housing Material		316 stainless steel or titanium
Dimensions		138 X 25 mm
Day-light rejection		-28 dB (re: 48 mW cm^-1)
Out put		0-1.25 V
		0-2.50 V
		4-20 mA

How do OBS and other optical sensors measure turbidity and suspended solids?

What light sources and detectors are used in OBS sensors?

Do I need to be concerned about fouling of OBS sensors?