MODEL 54eA | SECTION 9.0 |
| CALIBRATION - FREE CHLORINE |
9.3FULL SCALE CALIBRATION
1.Place the sensor in the process liquid. Be sure the controller has been programmed for manual pH correction and the pH is 7.00. Adjust the sample flow until it is in the range recommended for the sensor. Refer to the sensor instructions sheet.
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.
Calibrate main sensor Zero main sensor Adjust temperature
ExitEnter
1.100ppm
Stabilizing . . . Wait
Abort Cont
1.100ppm
Calibrate : 1.100 ppm
ExitEdit
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 free 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
To view the sensitivity from the main display, press any key to enter the main menu. Press the ê 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 Section 16.5 for assistance.
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