Xylem Sentix ORP 900 - Manual (Page 8)

Activating platinum electrodes SenTix
18 ba75845e01 08/2009
Cleaning Remove water-soluble contamination by rinsing with deionized water. Re-
move other contamination as follows:
After cleaning Rinse the electrode with deionized water.
Activating platinum electrodes
First-time
activation during
installation and as
required
For first-time activation use the activation powder from the SORT/RH reagent
set (component of the SORT/RH reagent set). Immerse the moist (but not
dripping) platinum electrode into the activation powder and rotate the
electrode several times in the powder. Then remove the activation powder
under flowing water with a soft brush (e.g. toothbrush).
Activation during
very long set-up
times
When changing from oxidizing to reducing test solutions and vice versa this
can result in set-up times that can take significantly more than an hour. In this
case pretreatment (activation) of the platinum surface can shorten the set-up
time. The type of pretreatment (reducing or oxidizing) is based on the pH val-
ue and the ORP voltage (U
H
) of the test solution where the latter must be es-
timated for the first measurement.
The type of pretreatment can then be determined using the following diagram
where U
H
is based on the normal hydrogen electrode:
Contamination Cleaning procedure
Fat and oil Rinse with water containing household wash-
ing-up liquid
Lime and hydroxide deposits Rinse with citric acid (10 % by weight)
Protein Immerse in pepsin cleaning solution PEP/pH
for approx. 1 hour.
Note: Make sure the level of the reference
electrolyte is above that of the cleaning solu-
tion.