# Tech Note 596 Detail

## Conductivity Sensor Calibration

Affected Products:
Problem/Symptom:
How do I calibrate the PASPort conductivity sensor?

PASCO Solution:

The PS-2116A PASPORT Conductivity Sensor should not require calibration to obtain a value that is accurate to within 10%. To obtain more accurate values, or verify that your conductivity probe is functioning to within specification, please follow the procedure below:

Preparation

1. Prepare (See pages 24-26 of the CI-6739A conductivity sensor manual.) or purchase a fresh calibration solution that is accurate to better than 0.5% and reads a conductivity near the maximum of the range of interest. The solution should be labeled with the conductivity C0, salt used, and temperature in Celsius at which the calibration applies Tc. Always immediately recap calibration solutions after use or the conductivity will increase due to evaporation of water.
2. Derive a corrected conductivity of calibration C0* by measuring the temperature of the calibration solution T in Celsius and adjusting the quoted value calibrated C0, either according to the equation that comes with the solution you are measuring or by using the generic equation for an aqueous solution: C0* = C0 * (1 + 0.02/(T - Tc)).
3. Rinse the conductivity probe with deionized water and dry it in order to avoid contaminating the solution.
4. Place the probe in the solution.
5. Press the appropriate range button for your type of measurement:
• Glass: 0-1,000 µS/cm
• Wave: 10,000-100,000 µS/cm
6. Tap and stir the probe until no air bubbles appear between the electrodes and the value stabilizes.
7. You should read within 10% from the calibration value C0* at this point.

PS-2116 Conductivity Sensor Calibration Procedure Using the GLX (>1 % Accuracy)

1. Navigate to Home/Sensors (F4).
2. Check that Conductivity Sensor is selected at the top of the screen.
3. Click Sensors (F4) and select Calibrate (3) .
4. Set the Calibration Type to 1 Point Slope.
5. Navigate to Pt 2 (uS/cm) and enter your value for C0* in µS/cm.
6. When the value stabilizes, click the F4 button ("Read Pt 2").
7. (The calibration is stored on the GLX, not the sensor; you will have to save the GLX file to save the calibration.)

PS-2116 Conductivity Sensor Calibration Procedure Using DataStudio 1.9.8

1. Click the Setup button in DataStudio.
2. DataStudio assumes that you have the 10 X conductivity probe connected. If you have a 1x probe connected, check Conductivity (1x Probe) and uncheck Conductivity (10 x Probe).
3. Click the Calibrate Sensors button.
4. Check 1-point slope.
5. Enter the value for C0* into the Standard Value text box for Calibration Point 2.
6. When the value stabilizes, click read from sensor.
7. (The calibration is stored in DataStudio, not the sensor; you will have to save the GLX file to save the calibration.)

Creation Date: 02/5/2007