Several years ago, Campbell Scientific introduced the OBS500 turbidity probe that featured dual backscatter and sidescatter sensors, a shutter mechanism that keeps the lenses clean, and a refillable biocide chamber that prevents fouling. Our newest product in this line, the OBS501, provides these features but performs better in heavy sediment load environments.
The OBS501 is constructed to prevent sand grains or packed sediment from getting wedged between the shutter and sensor body, which inhibits the shutter’s movement. To do this, the OBS501's shutter and body were designed to eliminate parallel surfaces between moving parts wherever possible. The probe also uses a flushing action that moves the sediment down and out of the cavity behind the shutter.
A new operating system allows the OBS501 to sense if the shutter’s motor is working harder than normal. If it is, the shutter moves slightly back and forth to dislodge sand grains before fully opening or closing. Changes to the SDI-12 instruction set also make it easier to place the shutter in the normally open mode.
Campbell Scientific tested the OBS501 in challenging sediment load conditions, and its performance was impressive. When released, the OBS501 promises to be a valuable new addition to our turbidity sensor family.