ProMinent DULCOTEST DO 1-mA-20 ppm Instrucciones De Servicio página 46

Troubleshooting
46
Checking measured value
Remove the sensor from the water and hold downwards at all
times.
Clean the sensor and the membrane and rub dry with a soft cloth.
Wait until the measured value is stable (keep away from direct
sunlight and any other heat source) (if "Measurement range
exceeded" appears (output signal = 22 mA) raise the maximum
upper value limit to 20 ppm (mg/l)).
Measure the air temperature at the sensor and enter in "Measure-
ment parameters setting?" menu.
If the DULCOMETER
salt content temporarily to "0" in the "Measurement parameters
setting?" menu.
Read off the measured value.
Compare the measured value with the corresponding value at the
measured temperature from the saturation table (in the Appen-
dix): if the measured value deviates less than ±15 % from this the
sensor is operating correctly.
Reset the salt content in the "Measurement parameters setting?"
menu to the original value.
Checking zero point
Produce oxygen-free water:
What you need
1 clean container for 1 l liquid (the sensor unit holder must be
immersed in the liquid later)
1 stirrer
1 l distilled water
1 g sodium sulphite (NaSO
1 mg cobalt (II) salt (cobalt(II)chloride hexahydrate; CoCl
*Purity rating "for analysis"
Mix the salts into the distilled water and stir.
Dip in the sensor and stir.
Read off the measured value when it is stable.
® D1C is correcting the salt content, set the
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3
· 6H O)*
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