Hach-Lange UVAS sc - Manual (Page 25)

Operation
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6. Edit the Factor x.xx and confirm. The current measured value is multiplied by
this factor, from 0.80-1.20, before it appears as a calculated value on the
display.
7. Press the back-button to leave the menu CALIBRATE.
8. Immerse sensor at the measuring location and confirm RETURN PROBE TO
PROCESS.
9. Confirm READY. Automatic wiping action and back to measurements.
4.7 Conversion into other total parameters
SAC 254 is an independent total parameter for the dissolved organic content of
water and evaluates, like all other total parameters, only ever a specific fraction of
the water load. Despite their major similarities, total parameters can only be
converted from one to another within certain limits. However, if a correlation is
found between SAC 254 and another total parameter, the converted measured
values from UVAS probes can be displayed as mg/l TOCuv, CSBuv etc.
To determine the correlation, first a measurement of the SAC curve should be
made over a few days. Only a regular daily curve with pronounced low and high
load times such as with municipal waste water offers a good basis for satisfactory
conversion.
At the times of day found for low and high load
• A representative sample should be taken at the UVAS probe location,
• The related SAC value should be read and
• A laboratory measurement of the parameter to be correlated should be
made.
Example:
Sample 1 SAC 254: 105 1/m ; TOC: 150 mg/l:
Sample 2 SAC 254: 35 1/m ; TOC: 38 mg/l:
The correlation entered should be regularly checked by means of comparative
measurements in the laboratory.
SENSOR SETUP
CONFIGURATION
SET PARAMETER TOCuv
MEAS UNIT mg/l
CORRELATION
PAIR 1
1 [1/m] = 105
1 [mg/l] = 150
PAIR 2
2 [1/m] = 35
2 [mg/l] = 38