IM 12B7J1-01E
< 3. Maintenance on operation >
3-3
●
Chemical Stains such as due to Metallic Adsorption
Place the glass electrode or liquid junction in a diluted hydrochloric acid solution (1 to 2%)
for several minutes (acid washing).
3.2
Replacing Consumable Parts
3.2.1
Replacing Glass Electrode
If buffer solution calibration becomes impossible due to deterioration of the glass electrode,
replace it with a new one. After the glass electrode is replaced, always carry out a buffer solution
calibration.
3.2.2
Replacing Liquid Junction
Even after washing the liquid junction, if normal measurement cannot be made, replace the liquid
junction.
When replacing the liquid junction, fill the sensor with KCl solution to just before the solution
overflows through the liquid junction mounting hole. Use a 3.3 mol/L KCl solution (a higher
concentration of KCl or KCl powder) for this application.
1. When the liquid junction
is to be removed.
2. When the liquid junction
is to be installed.
F3.4.ai
Figure 3.4
Replacing Liquid Junction
3.2.3
Replacing O-rings for Glass Electrode
As the inside of the glass electrode mounting hole must have high insulation resistance,
fluorocarbon rubber O-rings - with superior chemical and heat resistance - are used for sealing.
Except for special uses, this O-ring does not need individual replacement. If any damage -
which might cause problems - is detected in the O-ring, as a rule, replace it along with the glass
electrode.
Although the O-ring can be replaced individually if the O-ring deteriorates much faster than the
glass electrode, it is recommended that the whole glass electrode be replaced to avoid possible
deterioration of the O-ring inside the glass electrode. For individual replacement of the O-ring,
use the one recommended by Yokogawa.
When installing the O-ring, wind a slip of paper or tape around the thread part on the glass
electrode so as not to scratch the O-ring. Otherwise, such scratches may damage its sealing
properties.
For ordering, refer to the Customer Maintenance Parts List (CMPL) at the end of the book to
check the appropriate part number of the O-ring.
12th Edition : Dec.14,2018-00
