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24
PROBE & MEMBRANE MAINTENANCE
The oxygen probe body is made of reinforced plastic for maximum durability.
A thermistor temperature sensor provides temperature measurements of the
sample. Use the protective probe cap when not in use.
To replace the membrane or refill with electrolyte, proceed as follows:
• Remove the protective cap by gently
twisting and pulling it off the body of
the probe (see fig. 1).
• Unscrew the membrane cap by turning
it counterclockwise (see fig.2).
• Wet the sensor by soaking the bottom
2½ cm (1") of the probe in electrolyte (HI
7041S) for 5 minutes.
• Rinse the new membrane cap (HI
76407A), supplied with the meter with
electrolyte solution while shaking it gently.
Refill with clean electrolyte solution.
• Gently tap the sides of the membrane
cap with your finger tip to ensure that
no air bubbles remain trapped. Do not
tap directly the bottom with your finger,
as this will damage the membrane.
• Make sure that the rubber O-ring sits
properly inside the membrane cap.
• With the sensor facing down, slowly
screw the membrane cap clockwise.
Some electrolyte will overflow.
The Platinum cathode (#8 in the Functional
Description page 4) should always be bright
and untarnished. If it is tarnished or stained,
the cathode should be cleaned. You can 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. Afterwards, rinse the probe with deionized
or distilled water and install a new membrane cap using fresh electrolyte and
follow the steps above. Recalibrate the instrument.
TWIST
AND
PULL
UNSCREW
fig. 1
fig. 2
