EUTECH INSTRUMENTS DO 6, Instruction Manual, Page: 17 / 76

Instruction Manual DO 6
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4 CALIBRATION
4.1 Important Information on Meter Calibration
Your meter has three measurement modes namely the DO % saturation
measurement mode, the DO mg/L (ppm) concentration mode and the
Temperature measurement mode.
Since the mg/L (ppm) concentration value of dissolved oxygen varies with
temperature, barometric pressure and salinity, the meter with its electrode has
to be calibrated with consideration to these factors to ensure a proper
measurement. Therefore, it is very important to set the proper temperature,
barometric pressure and salinity values in the meter prior to any calibration or
measurement process. Since the dissolved oxygen measurements in %
saturation will linearly affect the mg/L (ppm) concentration measurement, it is
important that the meter has to be first calibrated in the % Saturation mode and
temperature mode before commencing the mg/L (ppm) concentration mode
calibration.
In % saturation calibration mode, the dissolved oxygen calibration values will
vary according to the barometric pressure correction set in the meter. Therefore
it is necessary to set the barometric pressure first before proceeding to %
Saturation calibration. The following table is an example which explains the
acceptance calibration values when % Saturation mode calibration is attempted
under different absolute value and under two different barometric pressures.
% Saturation factory
default value
Acceptance Calibration Value
(760mmHg)
Acceptance Calibration Value
(700mmHg)
less than 10% 0% 0%
10.1% to 49.9% Err.1 (error 1) Err.1 (error 1)
50% to 200% 100% 92.1%