Hach 9186, Instrument Manual

Page: 35 / 52

Calibrating the Sensors
35
6.4.2 Chemical Zero Calibration
Note: Calibration can be stopped at
any time by pressing
ESC
. The
instrument will then revert to the
previous calibration.
In this procedure, use a sample that does not contain hydrazine or any other
oxygen scavengers. Ensure that the sample source has a sufficient flow rate and
that the sample is adequately mixed.
1. From the Main display, push the
RIGHT ARROW
key.
2. Use the
LEFT ARROW
key to highlight CALIBRATION. Press
ENTER
.
3. Use the
LEFT ARROW
key to highlight CONC. CALIB. Press
ENTER
.
4. Use the
LEFT ARROW
key to highlight ZERO. Press
ENTER
.
5. Press
ENTER
to select PROGRAMMING.
6. Use the
RIGHT ARROW
key to highlight CHEMICAL. Press
ENTER
.
7. Press the
ESC
key once.
8. Use the
LEFT ARROW
key to highlight EXECUTION. Press the
ENTER.
9. The CAL message flashes, indicating that the instrument is in calibration
mode. Wait for a stable current, then press OK. The instrument displays the
zero for a few seconds, then returns to the previous level.
10. Press the
ESC
key once.
6.4.3 Slope Calibration
Note: Collect the sample for
reference analysis from the inlet
tube before it enters the analyzer
because a significant amount of
hydrazine is consumed during
passage through the measurement
cell.
1. From the Main display, push the
RIGHT ARROW
key.
2. Use the
LEFT ARROW
key to highlight CALIBRATION. Press
ENTER
.
3. Use the
LEFT ARROW
key to highlight CONC. CALIB. Press
ENTER
.
4. Use the
LEFT ARROW
key to highlight SLOPE. Press
ENTER
. The CAL
message flashes, indicating that the instrument is in calibration mode.
5. Wait for a stable current, then press OK, then immediately take a sample for
comparison analysis.
Note: Hach recommends using the
DR2500/DR4000 hydrazine or
carbohydrazide standard methods
8141 and 8140.
6. Adjust the value and units of the hydrazine concentration to the reference
value obtained by a standard method. To change a numeric value:
a. Select the value with the
LEFT ARROW
key.
b. Use the
RIGHT ARROW
key to highlight and change the leftmost digit.
c. Press the
ENTER
key to move to the next digit to the right.
d. Use the
RIGHT ARROW
key to change additional digits as needed.
e. Press the
ENTER
key as many times as needed to accept the value.
7. The analyzer then displays the date of the last calibration, along with the
calculated slope. Alter the date if necessary.