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8) Withdraw about 10 ml of water from the suspender and add it to the tea
cup containing the dry sediment. Stir the water-sediment mixture into a
homogeneous slurry, breaking up clumps of sediment as you go.
9) Pour the sediment slurry into the suspender and rinse the cup with
suspender water until it is clean. Make sure all the sediment gets from the
cup to the suspender.
10) Compute the SSC value in g L
SSCcalculator spreadsheet (TABLE 7-2), or use the SSC formula, Section
7.1.1, General Guidance, and enter the SSC value in the Value box.
11) Click the View Sensor button to see the ND and FD counts before they are
recorded. Adjust the gain if necessary, then click the Record button.
12) The second calibration pair of points will appear on the graph and the data
will be listed in the table. If the data for the current point is unacceptable
for any reason, too much or too little gain for example, highlight the data
line number (#) and click the Delete button. Adjust the gain and record it
again with the same SSC value.
Do not proceed to the next SSC value until you are
CAUTION
satisfied with the current data. Once you add sediment to
the suspender, you cannot remove it.
13) Repeat Steps 7 through 12 for the remaining SSC values following the
guidelines provided above. When the calibration data is complete, the data
table and plot will look like the ones shown below.
14) To compute the lookup tables, click the Calculate Fit button and supply
the requested information. Referring to FIGURE 7-2, pick point 'a' by
counting the number of data points on the ND curve from the origin (0, 0)
to the first point beyond where the ND and FD curves cross, 6 in FIGURE
7-2. Select 'b' at the first point on the falling limb beyond the ND peak
where it becomes linear, 10 on FIGURE 7-2. Point 'c' is the first point in
OBS-5+ System
–1
for the current calibration point with
27
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