TURTLE
TOUGH
®
14
Replacement of the Cathode Membrane
The cathode membrane has to be replaced immediately in cases where over-
pressure during refilling of the electrolyte has led to a shift in the position of
the membrane, or where the sensor has not been stored in water over a longer
period resulting in a loss of membrane elasticity.
The steps for replacing the membrane are as follows:
1. Unscrew protective cap (or paddle holder).
2. Pull off the first red collar.
3. Pull off the O-Ring.
4. Pull off the second red collar; the membrane normally comes off at the same
time.
5. Hold the sensor vertically and check whether electrolyte is visible in the
white electrolyte channels next to the cathode. If this is not the case
make “pumping movements” with your thumb on the pressure-compen-
sation membrane until electrolyte appears in all the electrolyte channels.
Note:
Never use a needle or other sharp objects to create flow, since the white
wick-like insert would otherwise be damaged! Doing this voids the warranty.
6. Wipe the cathode clean with tissue-paper, but do not polish it because the
“scratched” surface helps to form a film of the electrolyte.
7. Put one drop of electrolyte onto the cathode.
8. Put on the membrane and pull slightly downwards at the comers; there must
be no wrinkles formed on the silver surface. You can use a Membrane Po-
sitioner TT-TOUGH-DO-MP for this if available. (See: Using the Membrane
Positioner)
9. Replace the red collar (with the smoothed-off edge forward) and push it
down until the groove of the O-Ring is again visible (but no further).
10. Fit the O-Ring.
11. Subsequently fit the second red collar (with the smoothed-off edge forward).
12. Using a sharp knife carefully cut off any projecting membrane material
below the second red collar.
13. Rinse membrane with water.
14. Screw on protective cap (or paddle holder).
After membrane replacement, recheck calibration (see: “Calibration Verification”).
Note:
The sensor must never be stored in a so-called zero solution! This would damage
the electrode and void the warranty.
