Ph Calibration Procedure - Hach pHD Sensor User Manual

8. Review the calibration result:
• Passed—the sensor is calibrated and ready to measure samples. The offset value is shown.
• Failed—the calibration offset is outside of accepted limits. Refer to
on page 16 for more information.
9. If the calibration passed, push ENTER to continue.
10. If the option for operator ID is set to Yes in the Calibration Options menu, enter an operator ID.
Refer to Change the calibration options
11. On the New Sensor screen, select whether the sensor is new:
Option Description
YES The sensor was not calibrated previously with this instrument. The days of operation and previous
calibration curves for the sensor are reset.
NO The sensor was calibrated previously with this instrument.
12. Return the sensor to the process and push ENTER.
The output signal returns to the active state and the measured sample value is shown on the
measure screen.
Note: If the output mode is set to hold or transfer, select the delay time when the outputs return to the active
state.

pH calibration procedure

Pre-requisites: Do a temperature calibration before doing a pH calibration. The accuracy of the pH
measurement depends on the accuracy of the temperature measurement.
One or two measurements are required for pH calibration of this sensor. Measurements are made
with the pH sensor in a beaker that contains a sample or reference solution or with the pH sensor
installed in the flow cell.
Note: The pH sensor should first be calibrated with a reference solution(s) in a beaker. Then the pH sensor can be
calibrated with a sample(s) in a beaker or in the flow cell.
The pH can be calibrated with 1 or 2 reference solutions or samples (1-point or 2-point calibration).
Calibration adjusts the sensor reading to match the value of a reference solution(s) or sample(s).
A calibration is done by putting the pH sensor in a reference solution or sample with a known pH
value and then entering that known value into the controller. A buffer calibration identifies the buffer
table corresponding to the chosen buffer and automatically calibrates the probe after it stabilizes.
1. To calibrate the pH sensor in a beaker:
a. Put the sensor in the reference solution or sample.
b. Make sure that the sensor is at least half immersed in the liquid
c. Stir the sensor to remove bubbles.
d. Wait for the sensor and solution temperature to equalize. This can take up to 30 minutes.
Figure 2 Sensor in reference solution or sample
2. To calibrate the pH sensor in the flow cell, install the pH sensor in the flow cell and turn on the
flow.
12 English
on page 14.
Troubleshooting
(Figure 2).