Hanna Instruments HI 88703 - Manual (Page 25)

25
O UT CAL RANGE FUNCTION
The instrument has a mechanism to prevent taking
measurements in a range where the calibration does
not assure the best results. The message “
Out of
Calibration Range” is displayed on the message
line in the following situations:
•When the forst calibration point is over 0.15 NTU and the reading is under 10 NTU.
•When two point calibration was performed and the reading value is over 40 NTU.
•When a three point calibration was performed and the reading is over 150% of the the third point value.
•When a four point calibration was performed and the reading is over 200% of the the fourth point value.
FIVE-POINT CALIBRATION (Ratio Turbidity only)
To perform a five-point calibration, continue the procedure with the following steps:
• Remove the fourth standard cuvette.
• Place the 2000 NTU standard cuvette (or the
fourth prepared formazin standard) into the holder,
with the cuvette mark aligned to the sign on the
instrument top.
• Close the lid and press the Read key. The
display will show the value blinking and the lamp
icon during measurement.
• At the end of the measurement, the calibration
is saved and the display will briefly show
“Store...”. The instrument returns in the main
screen.
CALIBRATION ERROR MESSAGES
If the value of the standard read during the calibration is too far from the set value, the instrument
will display a standard low or a standard high message.
Check if the correct standard is used or prepare a fresh standard, if formazine is used, and repeat the
reading of the standard.
If the calculated calibration coefficients are outside
a certain range a calibration error message is
displayed.