Hanna Instruments HI 8050 - Manual (Page 57)

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CALIBRA CALIBRA CALIBRA CALIBRA CALIBRATION PROCEDURES TION PROCEDURES TION PROCEDURES TION PROCEDURES TION PROCEDURES
IMPORTANT WARNING !!!
The pH and EC sensors of Fertigation Controller must be connected ONLY
via HI 98143-22 series transmitters which are function using current injec-
tion principle (4-20mA). The sensors cannot be directly connected to the
controller.
SENSOR CALIBRA SENSOR CALIBRA SENSOR CALIBRA SENSOR CALIBRA SENSOR CALIBRATION PROCEDURE TION PROCEDURE TION PROCEDURE TION PROCEDURE TION PROCEDURE
The purpose of calibrating the Sensor’s used in conjunction with the Fer-
tigation Controller is to compensate and adjust the output of the sensors
to align with the software of the controller. As time passes the sensors
change output slightly due to wear and age making calibration necessary
for optimum performance. Monitoring probe performance with known stan-
dards and buffers easily identifies the need for calibration. The calibration
procedure is performed using panel S67
S67 S67 S67 S67 (CALIBRATE SENSOR) and each
analog sensor is assigned a channel number which is the index for panel.
For each sensor chosen for calibration two measurements with two differ-
ent known standards are used (e.g. pH 7.01 and pH 4.01 buffer used for
pH sensor calibration). For each of the 2 stages of calibration, the cali-
bration panel displays the actual reading and a reference input. The buffer
value is entered in the reference input. Prior to calibration of pH and EC
rinse the sensor in pure water to ensure a clean probe and avoid cross
contamination. Place the sensor in the first standard or buffer and wait for
stabilization. Once the reading is stable press ENTER
ENTER ENTER ENTER ENTER to advance to stage
2. Rinse again and place the electrode in the second standard, wait for
stabilization and then press ENTER
ENTER ENTER ENTER ENTER. The calibration is complete and the
panel will display “done”.
For best results the calibration buffers (standards) should be considerably
different (e.g. pH 7.01 and pH 4.01 buffer) but not excessively close to the
limits of the sensor range. After the calibration is complete (both calibra-
tion stages complete) rinse and reinsert the probe into the 2 standards to
ensure accuracy of calibration. If the probe does not read correctly this
may indicate that the same solution (or nearly the same) was used in both
stages of calibration or improper values were supplied as a reference or
the probe is malfunctioning. For temperature sensor calibration the fol-
lowing items are needed: a reference thermometer, a water and ice mix-
ture, hot water (50°C). For the first calibration step fully immerse the tip of