ELMETRON CO-505, User Manual

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10. OXYGEN CONCENTRATION MEASUREMENT
Before starting the oxygen concentration measurement the meter should be
prepared for work (chapter 6) and the oxygen sensor calibrated (chapter 9).
The measurement in % of saturation does not require additional
measurements of the temperature, salinity or atmospheric pressure.
However, frequent measurements in mg/l depend on these factors. This
influence is counted automatically by the device, which takes into
consideration the temperature value measured by the sensor or - in case of
manual compensation - the value entered by the user. The oxygen sensor is
equipped with an additional system compensating the temperature influence
on the membrane. Because of limited accuracy of this compensation the
highest accuracy can be achieved by calibrating the sensor at the same
temperature at which the measurement will be carried out. The
measurement error increases together with the difference between the
calibration
and measurement temperatures and results from
characteristic features of the sensor, not the device. If higher accuracy is
required, the interval from the last calibration must be additionally taken into
consideration (signal drift). If the salinity of the tested solution is insignificant,
the measurement can be started without entering its value (value 0.00 g/l
should be entered). Before making accurate measurements, the salt
content in the tested solution should be determined. The easiest way to
determine salinity is conductivity measurement with conversion to NaCl. The
salinity value is introduced according to the section 8.2.
10.1. Measurement with automatic temperature compensation
In order to make the measurement with automatic temperature
compensation:
-
connect the temperature probe with the meter;
- choose the resolution according to the section 6.2 and choose the number
of the oxygen sensor according to the section 6.3;
-
insert the oxygen sensor and the temperature probe to the measured
solution;
-
turn the meter on with the button;
-
with the
button choose the oxygen measuring function;
-
choose the unit according to the section 8.1;
-
in case of accurate measurements in mg/l enter the salinity value (section
8.2);
-
check or simulate the flow of the measured solution;
-
wait till the result stabilises (about 1
÷
1.5 min - depends on the probe)
and read the result.