Hanna Instruments hi 9141 사용자 설명서
13
13
TAKING MEASUREMENTS
Make sure the meter has been
calibrated (see page 9) and
the protective cap has been
removed. Immerse the tip of
the probe in the sample to be
tested.
calibrated (see page 9) and
the protective cap has been
removed. Immerse the tip of
the probe in the sample to be
tested.
Make sure the temperature sensor is also
immersed.
immersed.
Allow approximately one minute for the meter
to stabilize and read the mg / l (ppm) value of
dissolved oxygen on the display.
to stabilize and read the mg / l (ppm) value of
dissolved oxygen on the display.
For accurate dissolved oxygen measurements
a water movement of 0.3 m/sec is required
at a minimum. This is to ensure that the
oxygen-depleted membrane surface is con-
stantly replenished. A moving stream will pro-
vide adequate circulation.
a water movement of 0.3 m/sec is required
at a minimum. This is to ensure that the
oxygen-depleted membrane surface is con-
stantly replenished. A moving stream will pro-
vide adequate circulation.
During field measurements, this condition may
be met by manually agitating the probe. Ac-
curate readings are not possible while the
liquid is at rest.
be met by manually agitating the probe. Ac-
curate readings are not possible while the
liquid is at rest.
During laboratory measurements, the use of
a magnetic stirrer to ensure a certain velocity
in the fluid is recommended. In this way,
errors due to the diffusion of the oxygen
present in the air in the solution are reduced
to a minimum.
a magnetic stirrer to ensure a certain velocity
in the fluid is recommended. In this way,
errors due to the diffusion of the oxygen
present in the air in the solution are reduced
to a minimum.
At all times, the time necessary for thermal
equilibrium to occur between the probe and
the measurement sample must be allowed (a
few minutes if the temperature difference is
only several degrees).
equilibrium to occur between the probe and
the measurement sample must be allowed (a
few minutes if the temperature difference is
only several degrees).
ppm READINGS
The ppm readings allow the
user to read the concentra-
tion of the dissolved oxygen
user to read the concentra-
tion of the dissolved oxygen
Untitled-22
14
14
directly on the display expressed in ppm
(mg/l).
(mg/l).
If the sample contains significant salinity
concentration or if you are performing the
measurements at an altitude different from
sea level, the readout values must be cor-
rected, taking into account the lower de-
gree of oxygen solubility in such occasions
as explained on pages 23-24.
concentration or if you are performing the
measurements at an altitude different from
sea level, the readout values must be cor-
rected, taking into account the lower de-
gree of oxygen solubility in such occasions
as explained on pages 23-24.
Remember to set the altitude and/or the
salinity before taking ppm measurements.
The meter will automatically compensate
for these factors.
salinity before taking ppm measurements.
The meter will automatically compensate
for these factors.
TEMPERATURE READINGS
The probe has a built-in temperature sensor.
Press the FUNCTION key to display the
measured temperature.
measured temperature.
Allow the probe to reach the thermal equilib-
rium before taking any measurement. Ther-
mal equilibrium can take several minutes to
be reached. The greater the difference be-
tween the temperature at which the probe
was stored and the temperature of the sample,
the longer the time will be.
rium before taking any measurement. Ther-
mal equilibrium can take several minutes to
be reached. The greater the difference be-
tween the temperature at which the probe
was stored and the temperature of the sample,
the longer the time will be.
If "°C ---.-" is displayed, it indicates that the
D.O. probe is not properly connected. This
also indicates the possibility of a broken probe
cable.
D.O. probe is not properly connected. This
also indicates the possibility of a broken probe
cable.
FUNCTION
°C
°C