LaMotte DO 6 Dissolved Oxygen Meter - Manual (Page 15)

window is +/- 40% of the factory default value. However the minimum point of
calibration is 2 mg/L.
When you recalibrate your meter in % saturation mode, old calibrations in %
saturation will be replaced while the % saturation offset adjustment will be
erased. However, recalibration in the mg/L (ppm) concentration mode will
only replace the old calibration in the concentration mode and do not affect
the calibration in the percentage saturation mode.
To completely recalibrate your meter, or when you use a replacement
electrode, it is best to clear all calibration data. To erase all the old calibration
data completely, see Section 7.6 (rSt.5) Reset to Factory Default.
4.2 Preparing the Meter for Calibration
Before starting calibration, make sure you are in the correct measurement
mode and in the correct calibration sequence. The temperature and the %
Saturation calibration must be done first before attempting to do the mg/L
(ppm) Concentration calibration.
In % Saturation, the meter is able to perform either a one point calibration or
a 2 point calibration. For one point calibration, it is recommended that you
perform a 100% Saturation calibration in saturated air. If you opt for 2 point
calibration, you can calibrate for 100% Saturation in saturated air and 0%
Saturation using a zero oxygen solution. The meter will take several minutes to
reach 0% Saturation value after submersion into the zero solution.
Rinse the probe well in the de-ionized (DI) water or rinse solution and wipe
the probe carefully taking care of the membrane.
Calibrate the meter in all the modes to ensure the highest accuracy throughout
the DO measurement range. In % Saturation calibration, should there be a
calibration failure for 0% Saturation slope calibration; the meter may have
exceeded the limit of 10% of the factory calibrated absolute value. The sensor
may have to be re- conditioned. Also, note that the DO 6 meter will not
perform 0% or 100% Saturation calibration for absolute value ranging from
10.1% to 49.9%. The meter also will not perform the mg/L (ppm)
Concentration calibration for an absolute value of less than 2.00 mg/L (ppm)
or calibration which is out of its window tolerance of +/- 40% from the factory
default value. An error message of “Err.1” will be indicated and will return the
meter to the measurement mode.
All new calibration values will automatically override the existing data. It is
recommended to calibrate the meter periodically and or if it is suspected to be
inaccurate.
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