Conductivity
The conductivity calibration should be verified every day the instrument is used. However, the conductivity
sensor is very stable and may hold its calibration for several weeks.
CALIBRATION TIPS
1. It is not necessary to calibrate conductivity, specific conductance and salinity. Calibrating one of these
parameters will simultaneously calibrate the others. YSI recommends calibrating specific conductance
(temperature compensated conductivity) for greatest ease and accuracy.
2. Ensure the conductivity sensor is clean and dry before performing a specific conductance calibration.
3. Always use fresh, traceable conductivity calibration solution when calibrating the conductivity sensor.
a. The shelf life of conductivity solution is one month after being opened. This is due to potential
changes in the value of the solution caused by evaporation which can occur after opening the bottle.
Be sure to write the open date on the bottle so you know that you are using good calibration solution.
b. Never calibrate with a conductivity solution that is less than 1.0 mS/cm. You are setting the slope on
a linear device so a good strong conductivity signal will give you the best performance. Use 1.0
mS/cm for fresh water, 10 mS/cm for brackish to estuarine water and 50 mS/cm for salt water. 1.0
mS (millisiemens) = 1000 uS (microsiemens).
4. Pre-rinse the cal cup and sensors with a small amount of calibration standard or rinse standard and discard.
5. When calibrating the conductivity sensor, the calibration solution must cover the top vent holes of the
conductivity sensor. If using a Quatro cable, the top vent hole is located on the side of the combination
conductivity/temperature sensor. If using a different cable, the conductivity sensor is integral to the cable and
the sensor has two vent holes located close to the cable. Ensure the entire conductivity sensor is submerged
in the solution or the instrument will read approximately half the expected value.
6. After placing the sensor into the solution, gently move the sensor up and down to remove any air bubbles
that may be trapped in the conductivity sensor.
7. If calibrating Specific Conductance, enter the value of the conductivity solution as it is listed for 25°C. Make
sure you are entering the correct units. 1 mS = 1,000 uS.
8. 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 conductivity readings (and your DO mg/L readings) will be erroneous. Typical
causes for this error message include: incorrect entries (entering 1000 uS/cm instead of 1.0 mS/cm), not
using enough solution to cover the vent holes, air bubbles trapped in the sensor, calibrating in conductivity
instead of specific conductance, dirty conductivity electrodes, and/or bad calibration solution.
9. After accepting a good calibration, navigate to the GLP file and check the conductivity cell constant for the
calibration. For highest accuracy, the cell constant should be 5.0 +/- 0.5. However, the acceptable range is 5
+/- 1.0. A cell constant outside of this range indicates that a questionable calibration was accepted.
TROUBLESHOOTING TIPS
If you get an error message during calibration, be sure that you are:
1. Entering the correct calibration value (1 mS/cm = 1000 uS/cm).
2. Calibrating in Specific Conductance mode.
3. Using enough solution to cover the vent holes on the sensor.
4. Dislodging any air bubbles that could be trapped in the sensor.
5. Using a fresh, traceable conductivity calibration solution.
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