Campbell OBS-3A Especificaciones descargar pdf (Pagina 38)

Section 6. Calibration

6.1.2 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 (e.g. 125, 250, 500 or 1000 NTU) and one at the high end

of the desired measurement range (e.g. 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.

6.1.3 OBS-3A Utility Software Steps

1. Open the calibration dialog box with and click the NTU button.

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

2. Enter the standard value in the Value box of the calibration dialog and

click the Record button. If mg/l or ppm are selected, choose a sample

duration from TABLE 6.2-1.

3. After the sample has been logged, the table and plot of calibration data

will be updated. Verify that the calibration value is what you intended it to

be.

4. Prepare the next NTU standard and put the OBS-3A in it. Repeat steps 1

and 2 for all calibration values.

5. After the calibration is complete, click the Compute button and inspect

the plot to verify that it resembles the example shown above.

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Campbell OBS-3A Especificaciones Pagina 38