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.
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.
OBS® is a registered trademark of Campbell Scientific.
Number of FAQs related to OBS-3+: 17
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These devices employ optical backscatter to measure light absorption and should produce comparable data, but variation is likely between sensors.
Possibly. Remember that the accuracy of the sensor is 0.5 NTU. If the drinking water standard is near 1, this sensor may not be a good match.
Yes. However, contaminants may colonize the optics, which could distort the readings when water returns. Periodic cleaning may be required.
The beam divergence angle of the sensor is 42°. (Within this 42° cone, 95% of the beam power is contained.)
The OBS-3+ or OBS300 provides two separate outputs to match the two turbidity ranges selected at the time of purchase. Use the curve that matches the turbidity range likely to be experienced during monitoring. Program the datalogger to record and store data from each output, or choose which output to use automatically depending on the turbidity.
Campbell Scientific does not offer a display that can be attached directly to the sensor; however, the datalogger used to capture and record the data may have a display.
The following are some suggestions:
This has not been tested; however, it is likely that, as the sensor moves through the water, disturbances or bubbles are created that could distort the turbidity measurements.
Sensors are calibrated at the factory for measurements up to 4,000 NTUs, if requested at the time of order. Sensor ranges cannot be adjusted outside the factory.
The accuracy is 0.5 NTU or 2% of reading.