CALIBRATION PROCEDURE
Calibration is simple and is recommended every time the
meter is switched on.
• Make sure the probe is ready for measurements (see
Probe Preparation), i.e. the membrane is filled with
electrolyte and the probe is connected to the meter
and properly polarized.
• Switch the meter on by pressing the
ON/OFF key.
• The "COND" message will be dis-
played for about 45 seconds to inform
the user that the probe is in auto-
conditioning mode (automatic
polarization) .
• Once “COND” disappears, the probe
is polarized and the instrument can
be calibrated.
• Remove the protective cap from the
D.O. probe.
• Press CAL. "----" appears on the
larger LCD together with "CAL" to
indicate that the instrument is in cali-
bration mode.
• The instrument will automatically stan-
dardize itself to the actual saturation
value. After approx. 1 minute it will
display "100%" to indicate that the
calibration is complete.
Notes:
• It is recommended to re-calibrate the meter when-
ever probe, membrane or electrolyte is changed.
• To exit the calibration mode, press CAL.
• Switching from readings in % O
2
to readings in
mg/L does not require recalibration.
PROBE & MEMBRANE MAINTENANCE
The D.O. probe body is made of reinforced plastic for
maximum durability.
A thermistor temperature sensor provides temperature
measurements of the tested sample. It is always recom-
mended to keep the protective cap on the probe when
not in use, to protect it against damage and dirt.
To replace the membrane or refill it with electrolyte,
proceed as follows:
• Remove the protective cap by gen-
tly twisting and pulling it off the probe's
body.
• Unscrew the membrane by turning it
counterclockwise with the other hand.
• Wet the sensor by soaking the bot-
tom 2.5 cm of the probe in electrolyte
(MA9071) for 5 minutes.
• Rinse the new membrane supplied
with the meter with electrolyte, while
shaking it gently. Refill with clean
electrolyte.
• Gently tap the sides of the mem-
brane with the finger tip to ensure
that no air bubbles remain trapped.
Do no directly tap the bottom with
the finger as this will damage the
membrane.
• Make sure that the rubber
O-ring is seated properly
inside the membrane cap.
• With the sensor facing
down, screw the mem-
brane cap clockwise.
Some electrolyte will over-
flow.
If the Platinum cathode is tarnished or stained, which
could be due to contact with certain gases or to an
extended use with a loose or damaged membrane, it
should be cleaned. Use a clean lint-free cardboard or
cloth and rub the cathode very gently side to side 4-5
times. This will be enough to polish it 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.
Note: To obtain accurate and stable measurements, it is
important that the surface of the membrane be in
perfect condition. This semipermeable membrane
TWIST
AND
PULL
UNSCREW
isolates the sensor elements from the environ-
ment, but allows oxygen to enter. If any dirt is
observed on the membrane, rinse it carefully with
distilled or deionized water. If any imperfections
still exist, or any damage is evident (such as
wrinkles or tears-holes), replace the membrane.
Make sure that the O-Ring is properly seated in
the membrane cap.
Note: If don’t take measurements for a few hours,
protect the probe with the supplied cap.
BATTERY REPLACEMENT
When the battery becomes weak, the
meter will display the blinking battery
symbol.
When the low battery indicator appears, only about 10 hours
of battery life remain. A low battery will result in unreliable
measurements. It is recommended to replace the battery
immediately.
Battery replacement must only take place in a non-hazard-
ous area using an alkaline 9V battery.
Turn the meter off, unscrew the two
screws on the rear of the instrument,
remove the cover and replace the 9V
battery with a new one. Install the bat-
tery while paying attention to its polarity
and reattach the cover.
ACCESSORIES:
MA840 D.O. probe
MA841 Spare membrane, 5 pcs
MA9071 Refilling Electrolyte solution, 230 ml
SPECIFICATIONS:
RANGE 0.0 to 45.00 mg/L (ppm) O
2
0.0 to 300 % O
2
0.0 to 50.0 °C
RESOLUTION 0.01 mg/L (ppm) O
2
0.1 %O
2
0.1 °C
ACCURACY (@25°C)
± 1.5% Full Scale mg/L (ppm) O
2
± 1.5% Full Scale %O
2
± 0.5 °C
TYPICAL EMC DEVIATION
± 0.3 mg/L (ppm) O
2
± 3.5 %O
2
± 0.5 °C
CALIBRATION Automatic in saturated air
TEMPERATURE COMPENSATION
Automatic, from 0 to 50°C
ALTITUDE COMPENSATION
0 to 4000 m; 100 m resolution
SALINITY COMPENSATION
0 to 80 g/L; 1 g/L resolution
PROBE MA840 (included)
ENVIRONMENT 0 to 50°C; 100% RH max.
BATTERY TYPE 1 x 9V alkaline (included)
BATTERY LIFE approx. 100 hours of use
AUTO-OFF after 4 hours of non-use
DIMENSIONS 200 × 85 × 50 mm
WEIGHT 280 g (with battery)
ISM605R1 11/03
35 g/l
9.0
8.6
8.3
8.0
7.6
7.4
7.1
6.9
6.6
6.4
30 g/l
9.3
8.9
8.6
8.2
7.9
7.6
7.3
7.1
6.8
6.6
°C
10
12
14
16
18
20
22
24
26
28
0 g/l
11.3
10.8
10.3
9.9
9.5
9.1
8.7
8.4
8.1
7.8
10 g/l
10.6
10.1
9.7
9.3
8.9
8.5
8.2
7.9
7.6
7.4
20 g/l
9.9
9.5
9.1
8.7
8.4
8.0
7.8
7.5
7.2
7.0
°F
50.0
53.6
57.2
60.8
64.4
68.0
71.6
75.2
78.8
82.4
Salinity (g/l) at Sea Level
