Campbell Scientific OBS-3A Turbidity and Temperature Monitoring System - Manual (Page 52)

OBS-3A Turbidity and Temperature Monitoring System
• 100 ml to deliver (TD) volumetric pipette
• 25 ml TD measuring pipette
• 2 gallons filtered distilled water (purified water from the super market
works fine)
• Slotted stainless steel stirring spoon
7.1.2 Preparation
1. Experience has shown that only three calibration points are needed to get
sub-1% accuracy. It is recommended to do one for clean filtered water, a
midrange value (125, 250, 500 or 1000 NTU) and one at the high end of
the desired measurement range (250, 500, 1000, or 2000 NTU).
2. Scrub the sensor, container, spoon, and glassware with detergent and water
and rinse everything twice with filtered water.
3. To avoid interference from incandescent and solar IR, perform calibrations
under fluorescent lighting and make field checks in the shade.
4. Start the OBS-3A Utility Software and wake the OBS-3A.
7.1.3 HydroSci Software Steps
Open the calibration dialog box under OBS-3A Configuation | Operations |
Calibration and click the Calibrate button. Choose the units of calibration
you would like to use: NTU or mg/L and then select OK. Follow the
instructions to place the OBS-3A in a turbidity standard.
You cannot change the OBS-3A calibration after
exiting the calibration dialog box. WARNING
1. Place the OBS-3A in a turbidity standard for NTU calibration or sediment
standard for mg/L calibration.
2. Enter the standard value in the Value box of the calibration screen and
press the Record Value button. After the sample has been logged, the plot
and table of calibration data will be updated. Verify that the calibration
value is what you intended it to be. If it is not correct, select the value in
the table and press Delete.
44