YSI ADV6600 - Manual (Page 63)

Section 4. Calibration and Diagnostics
ADV6600
Y S I
Environmental
Page 53
A 1-point calibration is used to adjust a previous calibration, generally using a pH 7 buffer. This
calibration procedure adjusts only the pH offset and leaves the previously determined slope
unaltered.
A 2-point calibration is used if the pH of the media to be monitored is known to be either acidic or
basic. For example, if the pH of a pond is known to vary between 5.5 and 7, a two-point calibration
with pH 7 and pH 4 buffers is appropriate. A 3-point calibration with an additional pH 10 buffer
will not increase the accuracy of this measurement since the pH is not within this higher range.
A 3-point calibration assures maximum accuracy when the pH of the media to be monitored cannot
be anticipated. In this procedure, the pH sensor is calibrated with a pH 7 buffer and two additional
buffers.
Calibration:
1. Attach the sonde to a ring stand in an inverted position with the clean, dry calibration cup
attached.
2. Add enough pH 7 buffer standard to the calibration cup to ensure that the pH and
temperature sensors are completely covered. Allow at least 1 minute for temperature
equilibration before proceeding.
3. From the Calibrate menu, select ISE1 pH to access the pH calibration choices and select
either a 1-point, 2-point, or 3-point calibration.
4. Input the value of the first buffer at the prompt. No matter how many calibration points
you are using, the first buffer should always be pH 7.
5. Press Enter and the current values of all enabled sensors will appear on the screen and
change with time as they stabilize in the solution. Observe the readings under pH and
when they show no significant change for approximately 30 seconds, press Enter. The
display will indicate if the calibration is accepted.
6. After the pH 7 calibration is complete, press Enter again, as instructed on the screen. If a
2- or 3-point calibration was chosen, rinse the sonde in deionized or distilled water and dry
the sonde before proceeding with the next pH buffer, following the same steps as outlined
above.
4-6.6. ORP
1. Attach the ADV6600 to a ring stand in an inverted position with the clean, dry calibration
cup attached.
2. Add enough solution with a known oxidation reduction potential value (we recommend
Zobell solution) to the calibration cup to ensure that the ORP sensor is completely covered.
Allow at least 1 minute for temperature equilibration before proceeding.
3. From the Calibrate menu, select ISE2 Orp.
4. Input the correct value of the ORP solution for the sample temperature. Press Enter.
5. Monitor the stabilization of the ORP and temperature readings. After no changes occur for
approximately 30 seconds, press Enter to confirm the calibration.