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FOUR-POINT CALIBRATION
To perform a four-point calibration, continue the
procedure with the following steps:
• Remove the third standard cuvet.
• Place the 750 NTU standard cuvet (or the fourth
prepared formazin standard) into the holder,
with the cuvet mark aligned with the sign on
the instrument top.
• Close the lid and press READ/TIMER
. The
display will show blinking dashes and the icons
for cuvet, detectors and lamp will appear during
measurement.
• At the end of the measurement, the four-point
calibration is completed and the instrument returns
automatically to measurement mode.
OUT CAL RANGE FUNCTION
The instrument has an Out Cal Range function to
prevent taking measurements in a range where the
calibration do not assure the best results. The range
where the calibration assures correct measurements
is up to 40 NTU for a two-point calibration and up
to 150% of the third point value for a three-point
calibration.
The display will show a blinking “CAL” tag each
time the measurements are taken outside the
calibration range.
CALIBRATION ERROR MESSAGES
• If the value of the standard read during the
calibration is too far from the set value, the
instrument will display “-LO-” or “-HI-” error
messages. Check if the correct standard is used or
prepare a fresh standard, if formazine is used, and
repeat the reading of the standard.
