Campbell-scientific OBS500 Smart Turbidity Meter with ClearSensor Tech Manuale Utente Scaricare il pdf (Pagina 35)

OBS500 Smart Turbidity Meter with ClearSensor™ Technology

TABLE 7-10. Change in TU value resulting from one hour of

evaporation of SDVB standard, i.e., loss of water but not particles.

Calibration-cup Size φ mm (φ in.)

250 TU 500 TU 2000 TU 4000 TU

100 (4) +0.26 +0.52 +2.10 +4.20

150 (6) +0.60 +1.20 +4.80 +9.70

Materials and equipment: OBS500 with cable, datalogger, large black

polyethylene plastic tub (0.5 M I.D. X 0.25 M deep) for measuring the clear-

water points, and 100-mm and 200-mm black PE (polyethylene) calibration

cups.

Procedure

1. Swab sensor with an alcohol-soaked towel to sterilize it. Position the OBS

sensor in a large, black tub of fresh tap water as shown in FIGURE 7-6 and

record a 10-second average of the low-range output. Record the average

output on the calibration log sheet.

FIGURE 7-6. Position of OBS500 in clean tap water in big black tub

2. Pour the first SDVB standard into the appropriately sized cup (see TABLE

7-9).

3. Position the OBS sensor in the cup as shown in FIGURE 7-7 and record

10-second averages of the low- and high-range outputs. Record the

average outputs on the calibration log sheet.

4. Pour the standard back into its container.

5. Wipe sensor with a clean, dry towel to remove residual standard.

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Campbell-scientific OBS500 Smart Turbidity Meter with ClearSensor Tech Manuale Utente Pagina 35