Emerson Rosemount FCL, Reference Manual, Page: 72 / 108

6.4.4 Procedure - manual calibration
Complete the following steps to manually calibrate the pH sensor.
Procedure
1. Obtain two buffer solutions.
Ideally, the buffer pH values should bracket the range of pH to be measured.
2. Remove the sensor from the flow cell. If the process and buffer temperatures are
appreciably different, place the sensor in a container of tap water at the buffer
temperature.
Do not start the calibration until the sensor has reached the buffer temperature.
3. Press MENU .
The main Menu screen appears. The cursor is on Calibrate.
4. Press ENTER .
5. Choose the sensor you wish to calibrate.
Sensor 1 is the chlorine sensor. Sensor 2 is the pH sensor.
6. Choose pH.
7. Choose Buffer Cal.
8. Choose Manual.
9. Choose Buffer 1.
10. Rinse the sensor with water and place it in the first buffer. Be sure the glass bulb and
reference junction are completely submerged. Swirl the sensor.
11. Watch the pH reading for sensor 2 (S2) at the top of the screen. Once the reading is
stable, enter the pH value of the buffer at the buffer temperature and press ENTER .
The display returns to the screen shown in step 9.
12. Choose Buffer 2.
13. Remove the sensor from the first buffer.
14. Rinse with water and place it in the second buffer. Be sure the glass bulb and
reference junction are completely submerged. Swirl the sensor.
15. Press ENTER .
16. Watch the pH reading for sensor 2 (S2) at the top of the screen. Once the reading is
stable, enter the pH value of the buffer at the buffer temperature and press
ENTER
.
If the calibration is successful, the screen below is displayed for five seconds. The
display then returns to the screen in step 7. If the calibration is not successful, the
existing calibration data is not changed. A screen appears identifying the error (high
slope, low slope, or offset error). For troubleshooting, see
Section .
17. To return to the main display, press MENU and then EXIT .
Calibrate Reference Manual
May 2019 00809-0100-3412
72 Emerson.com/Rosemount