14
15
•
With the sensor facing down, screw the
membrane cap clockwise. Some electro-
lyte will overflow.
The platinum cathode sensor should always be
bright and untarnished. If it is tarnished or
stained, which could be due to contact with
certain gases or extended use with a loose or
damaged membrane, the cathode sensor
should be cleaned.
Use a clean, lint-free cardboard or cloth. Rub the
cathode very gently side to side 4-5 times. This
will be enough to polish and remove any stains
without damaging the platinum tip. Then, rinse
the probe with deionized or distilled water.
Install a new membrane and fill it with fresh
electrolyte following the instructions above.
Recalibrate the instrument.
Important: For accurate and stable measure-
ments, it is important that the surface of the
membrane is in perfect condition. This perme-
able membrane isolates the sensor elements
from the environment but allows oxygen to
enter. If any dirt is deposited on the membrane,
rinse it carefully with distilled or deionized
water. If any imperfection is observed, or any
damage is evident (such as wrinkles, tears or
holes), the membrane should be replaced. Make
sure that the O-Ring is properly seated in the
membrane cap.
PROBE & MEMBRANE MAINTENANCE
The oxygen probe body is made of reinforced
polypropylene for maximum durability.
A built-in thermistor sensor measures the tem-
perature of the sample. It is recommended to
keep the protective cap on the probe when the
it is not in use.
To replace the membrane or refill it with
electrolyte, proceed as follows:
•
Remove the protective
cap by gently twisting and
pulling it off the probe
(fig.1).
•
Unscrew the membrane
by turning it counterclock-
wise (fig.2)
•
Wet the sensor by soak-
ing the bottom (2.5 cm /
1") of the probe in HI7041S
electrolyte solution for 5
minutes.
•
Rinse a new membrane
(HI 76407A) with some
electrolyte while shaking
it gently. Refill with fresh
electrolyte.
•
Gently tap the sides of
the membrane with your
finger to ensure that no
air bubbles remain
trapped. Do not directly
tap the bottom as this
may damage the mem-
brane.
•
Make sure that the rub-
ber O-ring is seated prop-
erly inside the membrane
cap.
TWIST
AND
PULL
fig. 1
UNSCREW
fig. 2
