ORP
The ORP calibration should be verified every day the instrument is used. However, a new ORP sensor may be
capable of holding its calibration for several days.
CALIBRATION TIPS
1. If using a pH/ORP combination sensor, calibrate pH first to ensure it is working.
2. If using an ORP sensor in a 6051010 or Quatro cable, calibrate the sensor in port 1 prior to calibrating the
sensor in port 2. The sensor in port 2 uses the reference of the sensor installed in port 1. Therefore, it is
important to verify that the port 1 sensor is working properly before calibrating the port 2 sensor. See ORP
Troubleshooting Tips for additional info.
3. Rinse the sensors and cal cup with a small amount of ORP calibration solution. Fill the cup so that the ORP
sensor tip and the temperature sensor are submerged in solution.
4. Enter the calibration value per the temperature reading. The value of ORP calibration solution is greatly
affected by temperature. The ORP solution should include a chart of solution values per temperature. If not,
contact the supplier of the ORP solution to obtain this information. The Pro Series ORP sensors use a
Ag/AgCl 3.5 M KCl reference. Be sure the value you enter is for this type of reference. If using the YSI Zobell
calibration solution, the Pro Plus will automatically determine the calibration value.
5. Wait for the readings to stabilize and then press enter to accept the calibration.
6. If you receive a warning message stating that the calibration is questionable, do not continue with the
calibration. Instead, select ‘No’ and investigate what is causing the questionable results. If you accept a
questionable calibration, your ORP readings will be erroneous. Typical causes for this error message
include: incorrect Sensor/Port setup in the instrument, a dirty sensor or bad calibration solution.
TROUBLESHOOTING TIPS
Typical working life for ORP sensors is approximately 12-24 months depending on usage, storage and
maintenance. Proper storage and maintenance generally extends the sensor’s working life.
Clean and recondition the sensor if the sensor exhibits a slow response in Zobell solution, i.e. it takes more than
90 seconds to stabilize when placed in Zobell.
If you get error messages during an ORP calibration, check the following:
1. Ensure the ORP calibration solution is good and not expired.
2. Ensure that the ORP sensor is installed in the correct port of the cable and the correct ISE is enabled in the
Sensor Setup menu.
a. If using an ORP or pH/ORP combo sensor in a 6051020 cable, ensure the sensor is installed in port
1.
b. If using an ORP sensor in a 60510, 6051020 or 6051030 cable, ORP should be enabled in ISE1 of
the instrument’s Sensor Setup menu.
c. If using a pH/ORP combo sensor in a 60510, 6051020 or 6051030 cable, ORP should be enabled in
ISE2 of the instrument’s Sensor Setup menu.
d. If using an ORP sensor in a 6051010 or Quatro cable, check to see if the ORP sensor is installed in
port 1 or port 2. If the ORP sensor is installed in port 1, enable ORP in ISE1 of the Sensor Setup
menu. If the ORP sensor is installed in port 2, enable ORP in ISE2 of the Sensor Setup menu.
5. If using a pH/ORP combo sensor in a 6051010 or Quatro cable, ORP will not be measured or reported.
6. If using a 6051010 or Quatro cable, you must have a sensor installed in port 1 for port 2 to operate.
Additionally, ensure that the sensor installed in port 1 is calibrated and in good working order. In 6051010
and Quatro cables, the sensors installed in port 1 and port 2 use the reference from the sensor installed in
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