Xylem 6-Series Multiparameter - Manual (Page 88)

Sondes Section 2
YSI Incorporated Environmental Monitoring Systems Operations Manual 2-82
pH
When selecting ISE1 pH, you will be given the choice of 1-point, 2-point, or 3-point calibrations.
Select the 1-point option only if you are adjusting a previous calibration. If a 2-point or 3-point calibration
has been performed previously, you can adjust the calibration by carrying out a one point calibration.
Immerse the sonde in a buffer of known pH value and press Enter. You will be prompted to type in the pH
value of the solution.
NOTE: The actual pH value of all buffers is somewhat variable with temperature and that the correct value
from the bottle label for your calibration temperature should be entered for maximum accuracy. For
example, the pH of YSI “pH 7 Buffer” is 7.00 at 25 C, but 7.02 at 20 C.
After inputting the proper pH value for your calibration temperature, press Enter again, and the screen will
display real-time readings that will allow you to determine when the pH and temperature readings have
stabilized. Pressing Enter will confirm the calibration. Then, as instructed, press Enter again to return to
the Calibrate menu. This calibration procedure adjusts only the pH offset and leaves the previously
determined slope unaltered.
Select the 2-point option to calibrate the pH probe using only two calibration standards. In this procedure,
the pH sensor is calibrated using a pH 7 buffer and a pH 10 or pH 4 buffer depending on your
environmental water. A two point calibration procedure (as opposed to a 3-point procedure) can save time
if the pH of the media being monitored is known to be either basic or acidic. 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. Three 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.
To begin the calibration, immerse the sonde in one of the buffers and enter the actual pH value depending
on your calibration temperature. Press Enter, and the screen will display real-time readings that will allow
you to determine when the pH sensor has stabilized. Pressing Enter will confirm the calibration.
Following the instructions on the screen, place the sonde in the second pH buffer, input the pH value, press
Enter, and view the stabilization of the values on the screen in real time. After the readings have
stabilized, press Enter to confirm the calibration. Then, as instructed, press Enter again to return to the
Calibrate menu.
Select the 3-point option to calibrate the pH probe using three calibration solutions. In this procedure, the
pH sensor is calibrated with a pH 7 buffer and two additional buffers. The 3-point calibration method
assures maximum accuracy when the pH of the media to be monitored cannot be anticipated. The
procedure for this calibration is the same as for a 2-point calibration, but the software will prompt you to
select a third pH buffer to complete the 3-point procedure.
ORP
Select ISE2 ORP to calibrate the ORP sensor. Immerse the sonde in a solution with a known oxidation
reduction potential value (we recommend Zobell solution) and press Enter. You will be prompted to enter
the ORP value of the solution. Press Enter, and monitor the stabilization of the ORP and temperature
readings. After no changes occur for approximately 30 seconds, press Enter to confirm the calibration.
Then, as instructed, press Enter again to return to the Calibrate menu.
AMMONIUM