10
11
mg/L READINGS
The mg/L mode give the dissolved oxygen
concentration directly in ppm.
If the sample contains significant salinity or if
the measurement is taken at a higher altitude
than sea level, the readout values must be
corrected, by taking into account the lower
degree of oxygen solubility in such conditions.
Compensation for altitude and sality effects
is possible with the HI 9143 model.
Altitude and/or salinity values should be set
before calibrating and taking measurements.
The meter will automatically compensate for
these factors (see “Altitude Compensation”
and “Salinity Compensation” sections).
% O2 SATURATION READINGS
The % O2 reading provides the rate of oxygen
saturation with reference to
100% at sea level.
T E M P E R A T U R E
READINGS
The secondary display will show the sample
temperature in Celsius degrees.
Allow the probe to reach thermal equilibrium
with the sample before taking any
measurement. The greater the difference
between the ambient temperature and the
temperature of the sample, the longer it will take
the probe to acclimatized itself to the sample.
TAKING MEASUREMENTS
Make sure the meter has been
calibrated and the protective
cap has been removed. Im-
merse the tip of the probe in the
sample to be tested ensuring
that the temperature sensor is
also immersed.
To display values in % satura-
tion, press RANGE.
For accurate dissolved oxygen measurements,
a water movement of at least 30 cm (12”)/sec is
required. This is to ensure that oxygen depleted
on the membrane surface is constantly replen-
ished. A moving stream will provide adequate
circulation.
During field measurements, this condition may
be obtained by manually stirring the probe.
Accurate readings are not possible while the
liquid is stationary.
During laboratory measurements, the use of a
magnetic stirrer to ensure a certain agitation of
the fluid is recommended. This way, any errors
due to the presence of air bubbles on the
menbrane surface are minimized.
For accurate measurements, allow sufficient
time for the thermal equilibrium to be reached
between the probe and the measured sample (a
few minutes if the temperature difference is
several degrees).
RANGE
SAMPLE
%
°C
