Yokogawa DO202 2-Wire Dissolved Oxygen Analyzer - Manual (Page 55)

IM 12J05C01-01E
6-4 Calibration Procedure
6-4. Calibration procedure using manual calibra-
tion method
6-4-1. Preparation
A. Cleaning
Confirm that the readings of the analyzer are
stable and measured with a clean sensor.
Otherwise move the sensor to a maintenance site
and wash off any dirt on the sensor membrane
Move the sensor back to the process water and
wait for the readings to stabilize.
B. Sampling
The manual calibration procedure involves
adjustment of the readings to a reference standard.
Normally this reference is a laboratory
measurement that analyses a sample that must
be identical to the sample measured with the on-
line analyzer.
The following precautions must be taken into
account:
• The sample must be analyzed directly after
sampling to avoid change of dissolved oxygen
concentration or temperature after sampling
• The reference standard must be analyzed with
a laboratory meter that is calibrated prior to
sample analysis
• The reference method must be calibrated with
the same calibration data as specified in ISO
5814 to avoid indiscrepancies
Most important calibration data are:
Dissolved oxygen concentration at saturation
conditions as function of temperature, barometric
pressure, altitude and salinity.
These data are included in this manual for
reference and verification of correct calibration of
reference analyzers. DO202 has taken all these
variables into account during the semi-automatic
calibration methods.
6-4-2. Procedure for manual slope (sensitivity) calibration
NO YES
ENT
NO YES
NO YES
Select the flashing digit with the key.
Increase its value by pressing the key.
When the correct value is displayed,
press ENT to enter the change.
After briefly displaying WAIT,
the display returns to
the normal readout.
YES
Press YES to return to the
measuring mode. (Single Point
adjustment only)
ENT ENT
ENT
YES
YES
ENT
FAIL TEMP.MAN
YES NO
ENT
NO MODE YES
MODE
%sat
ppb
CAL
DISPLAY
ppm
HOLD
OUTPUT
SET HOLD
SERVICE