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1. If the sensor was just zeroed, place the reagent uptake tube back in the bottle. Once the flow of reagent starts, it takes
about one minute for the sensor current to begin to increase. It may take an hour or longer for the reading to stabilize. Be
sure the sample flow stays between 80 and 100 mL/min and the pressure is between 3 and 5 psig.
2. Adjust the chlorine concentration until it is near the upper end of the control range. Wait until the controller reading is sta-
ble before starting the calibration.
9.3 FULL SCALE CALIBRATION
MODEL 54eA SECTION 9.0
CALIBRATION - TOTAL CHLORINE
1.100 ppm
Stabilizing . . . Wait
Abort Cont
1.100
ppm
Calibrate
: 1.100 ppm
Exit Edit
Calibrate main sensor
Zero main sensor
Adjust temperature
Exit Enter
3. From the main display, press any key to obtain the main menu. With the
cursor on “Calibrate,” press Enter (F4).
NOTE
If Hold was enabled in Section 5.6, the hold screen will appear. To acti-
vate hold, refer to Section 5.6, step 11.
Press Enter (F4).
4. Press Cont (F3). “Wait” flashes until the sensor is stabilized.
If the controller appears locked, the reading is not stable enough. Wait until
the process readings are stable before starting the calibration.
Alternatively, increase the stability concentration or reduce the stability
time. See Section 5.11. Calibrating while readings are unstable may sub-
stantially reduce accuracy.
5. Once the reading is stable, the screen at left appears. Sample the process
liquid. Make a note of the reading before taking the sample. Immediately
determine total chlorine. Note the controller reading again. If the present
reading (X) differs from the reading when the sample was taken (Y), cal-
culate the value to enter (C) from the following formula:
C = (X/Y) (A)
where A is the concentration of chlorine measured in the grab sample.
Press Edit (F4). Use the arrow keys to change the concentration in the sec-
ond line of the display to the desired value. Press Save (F4) to store the value.
6. Press Exit (F1) four times to return to the main display.
NOTE
If Hold was activated during calibration, “Hold Mode Activated” will
continue to flash in the main display. Return the sensor to normal and
deactivate Hold. Refer to Section 5.6, step 11.
7. During the calibration, the analyzer stores the measured current and cal-
culates the sensitivity. Sensitivity is the sensor current in nA divided by the
measured concentration. The sensitivity of the 499ACL-02 (total chlorine)
sensor is about 1300 nA/ppm at 25°C.
To view the sensitivity from the main display, press any key to enter the
main menu. Press the key once. Then press Enter (F4) to display the
diagnostic variables. The sensitivity is the third line on the screen. Note the
units: nA is nanoamps, μA is microamps.
NOTE
During calibration, ERROR and WARNING messages may appear. If an ERROR message appears, press Exit (F1)
to leave and return to the previous screen. If a WARNING message appears, press Cont (F3) to continue the cali-
bration or press Abort (F1) to leave. Continuing the calibration after a warning message appears may cause substan-
tial errors in the subsequent measurement. Refer to the SCS921 instruction manual for assistance.