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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.
Mount the glass electrode on the sensor body as per the following procedure:
(1) Take off the glass electrode from the sensor body, do not remain a droplet into the electrode
mounting hole.
(2) Remove the cap for new glass membrane. Wipe off any solution remaining on the O-ring
with a tissue or other material.
(3) Remove the cap for the gold-plated pin.
(4) Confirm that there is no damage on the O-ring that might affect its sealing performance.
(5) Mount the glass electrode on the sensor body. Insert the electrode in the mounting hole and
screw it clockwise until the O-ring fits tightly in the hole.
CAUTION
• As shown in Figure (a), the cap for the glass membrane contains the solution to keep wet
(pH4 buffer solution). Do not splash the solution when removing the cap. Remove the cap
carefully because the rod beside the glass membrane is very fragile.
• Before mounting the glass electrode on the sensor body, make sure that the O-ring and the
gold-plated pin are not wet. Wipe off any remaining solution.
• Make sure that there are no droplets in the mounting hole. Wipe off any droplets, or they
may cause insulation failure.
• Use the electrode within one year after purchase. The solution to keep wet gradually
evaporates over time. A glass electrode whose glass membrane has dried out does not
provide stable readings until it gets used to the solution. As shown in Figure (b), place in
advance the glass electrode either in the pH4 or pH7 buffer solution for more than a day
before using.
Cap for the gold-plated pin
Cap for the glass membrane
Solution to keep wet (inside)
(a)
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.
< 3. Maintenance on operation >
Make sure the part above the O-ring is not wetted.
Case part No.: K9008WT
(b)
IM 12B7K1-02E
11th Edition : Dec.14,2018-00
3-3
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