LaMotte 1761 Manual - Polarization
10
7. Do not move the membrane cap assembly. Dip the electrode into the
assembly and remove it. Repeat this step several times. With each dip,
progressively push the electrode deeper into the electrode solution in
the assembly. This dipping technique will minimize the introduction of
air bubbles into the electrolyte solution. Air bubbles can compromise
dissolved oxygen measurements.
8. Carefully pick up the membrane cap assembly and slowly screw it onto the
electrode in a counter-clockwise direction until it is fully tightened. While
tightening the cap, excess electrolyte solution will leak out. This is normal
and desirable since it will minimize air pockets in the solution. Air pockets
can compromise dissolved oxygen measurements. If the electrode solution
does not overf ow, an insuff cient amount was added. Repeat the process
with a new membrance cap assembly if air bubbles or air pockets are visible
when the meter is inverted. Membrane cap assemblies can not be reused.
NOTE: Air bubbles outside the cathode (6 mm in diameter in the center
of the probe) will not interfere.
9. Rinse excess electrolyte from the outside of the membrane cap assembly
and the electrode.
Polarization
If the meter has not been used for seven (7) days or longer the electrode will not
be fully polarized. A fully polarized electrode is indicated by a small, f ashing,
asterisk in the lower right corner of the display when the meter is OFF. If the
asterisk is absent, turn the meter ON and allow the electrode to fully polarize.
This may take 2-3 minutes. The asterisk will appear to indicate full polarization.
Calibration
Calibration should be performed daily.
(Be sure the electrode is f lled and fully polarized before calibrating)
1. Turn the meter ON.
2. Press and hold MODE until ‘%’ is displayed.
3. Remove the electrode cap. The electrode membrane must be clean and
dry or the calibration will be incorrect. Do not touch the membrane. Skin
oil will affect the electrode response.
CALIBRA
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