USF Wallace & Tiernan DEPOLOX 4, Manual

Page: 19 / 113

6.6 MEASURED VALUE CALIBRATION
1. After completing the zero calibration, open shut-off valve (page 10, item 20)
and wait at least 2 minutes.
2. Activate manual operation mode and press key "F" until "DPD mg/l" is
displayed.
3. Take a sample from the drain hose and determine the content of free
chlorine, chlorine dioxide or ozone by means of the DPD method (colorimetre
or photometer).
4. Press direction keys until the determined value is displayed on the LED
display.
5. Enter this value into the amplifier memory by pressing key "E". The measuring
cell is now calibrated.
6. Leave the F menu and return to manual operation mode by pressing
MANUAL/AUTOMATIC key. Press this key again to switch to automatic
operation of the amplifier. The controller outputs (optional) are now activated.
6.7 CHEMICAL ANALYSING METHODS
The chemical determination of chlorine residual or other oxidising agents may be
performed conveniently by using either a colorimeter or a photometer. Both instruments
furnish precise values and are easy to handle. For chlorine and ozon measurements,
DPD tablets or DPD liquid have to be added to the water sample. The water colour is
subsequently checked against a colour chart or in the photometer (refer to the respective
instruction manuals).
To keep the measuring error as small as possible, compute the average of 3
consecutive samples.
19