MODEL 54eA | SECTION 13.0 |
| CALIBRATION - pH |
13.3MANUAL TWO-POINT CALIBRATION
1.Be sure the pH feature has been enabled. See Section 5.8.
2.The controller comes from the factory set for automatic pH calibration. To do a manual calibration, the factory default setting must be changed. Refer to Section 5.8.
3.Obtain two buffer solutions. Ideally the buffer pH values should bracket the range of pH values to be meas- ured. Also obtain a thermometer. The pH of most buffer solutions is a function of temperature. To calibrate the sensor properly, the pH of the buffer at the measurement temperature must be entered in the analyzer.
4.Remove the sensor from the process liquid. 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 sen- sor has reached the buffer temperature. Thirty minutes is usually adequate.
Adjust temperature Calibrate pH Output trim
ExitEnter
ExitEnter
4.01pH
Calibrate point 1
Abort Cont
5.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 activate hold, refer to Section 5.6, step 11.
6.Press the ê arrow key three times to move the cursor to "Calibrate pH". Press Enter (F4).
7. With the cursor on
8.Rinse the sensor and thermometer with water and place them in buffer 1. Be sure the glass bulb and junction are completely sub- merged. Swirl the sensor. Press Cont (F3). "Wait" flashes until the reading stabilizes. The large number on the first line is the measured pH based on the previous calibration.
If the controller appears locked, the reading is not stable enough. Investigate and correct the cause of the noise or drift (see Section 14.8). Alternatively, change the stability limits (see Section 5.8) and repeat the calibration.
4.01pH
Pt. 1 : 04.00pH 25°C
Exit | Pt 2 | Edit |
9.The screen at left appears once the reading is stable. Press Edit (F4) and use the arrow keys to change the reading to the pH of the buffer at the measured temperature. Most commercial buffers have a table of pH values as a function of temperature on the label. Press Save (F4) to store the value. If the pH value on the first line is correct, press Pt 2 (F3) and go to step 11.
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