OBS-3+

Turbidity Sensor

The OBS-3+ is a submersible, turbidity probe that has sideways-facing optics. It uses OBS® technology to measure suspended solids and turbidity for applications ranging from water quality in freshwater rivers and streams to sediment transport and dredge monitoring. Campbell Scientific dataloggers measure the OBS-3+ probe's output and calculate turbidity.

Benefits and Features

  • Sideways facing optics avoid obstructions above and below the probe
  • Measures suspended solids and turbidity for up to 4000 NTUs
  • Provides a compact, low-power probe that is field proven
  • Accurate and rugged
  • Compatible with all Campbell Scientific dataloggers (including the CR200(X) series)
  • Stainless-steel body allows use down to 500 m in fresh water
  • Titanium body allows use down to 1500 m in fresh or salt water
  • Fitted with MCBH-5-FS, wet-pluggable connector—multiple mating cable length options available
  • Offers an optional five-point sedimentation calibration for better measurements (see Ordering Info)

Technical Description

The OBS-3+ uses its sideways-facing optics to emit a near-infrared light into the water. It then measures the light that bounces back from the water’s suspended particles.

If an obstruction is in the emitted light’s range, the light will scatter back and the turbidity reading will be too high. This probe's sideways-facing optics avoids obstructions above and below the probe. The OBS300 is available for locations that have obstructions around the sides of the probe.

Specifications

  • Maximum Depth
    • Stainless-Steel Body: 500 m (1640.5 ft )
    • Titanium Body: 1500 m (4921.5 ft )
  • Drift: less than 2% per year
  • Maximum Data Rate: 10 Hz
  • Infrared Wavelength: 850 nm ±5 nm
  • Daylight Rejection: -28 dB
    (re:48 mW/cm²)
  • Optical power: 2000 µW
  • Maximum Concentration Range
    • Mud: 5,000 mg/l to
      10,000 mg/l
    • Sand: 50,000 mg/l to
      100,000 mg/l
  • Turbidity Accuracy: 2% of reading or 0.5 NTU
    (whichever is larger)
  • Concentration Accuracy
    • Mud: 2% of reading or
      1 mg/l (whichever is larger)
    • Sand: 4% of reading or
      10 mg/l (whichever is larger)
  • Housing material: 316 stainless steel or titanium
  • Connector: MCBH-5-FS, wet-pluggable


-2.5 Output Option

  • Output Voltage = 0 to 2.5 V over selected NTU range
  • Supply Voltage = 5 to 15 Vdc
  • Current Drain = 15 mA


-5 Output Option

  • Output Voltage = 0 to 5 V over selected NTU range
  • Supply Voltage = 5 to 15 Vdc
  • Current Drain = 15 mA


-20 Output Option

  • Output Voltage = 4 to 20 mA over selected NTU range
  • Supply Voltage = 9 to 15 Vdc
  • Current Drain = 45 mA