Best Practices for QA/QC for EXO Conductivity/Temperature sensors.

Below are a few checks you may want to include these in your organization’s standard operating procedures to ensure the highest data quality. While these steps focus on a conductivity/temperature probe, there are also many other sensor checks that can be used as part of a QA/QC process. We’ll make EXO University (www.EXO-University.com) available for free in case you are interested in learning about additional sensors.

 

Follow the processes below to help ensure a temperature/conductivity probe is working to its stated specifications:


Preparation:

Before performing any QA checks, it’s important that any probes are thoroughly cleaned of any debris or biofouling, as this can skew the data used in our test processes.
(Note: Several cleanings may be required to fully remove field contaminants.)

 

Tips:

  • Remove any copper screens, if equipped.
  • Inspect the probe’s Conductivity cells for hard fouling. If barnacles or other fouling is present, soak the probe in white vinegar for 15 minutes to weaken any buildup.
  • Using the EXO CT cleaning brush, remove all fouling and ensure both conductivity cells are clean. Use dish-washing soap with tap water to clean.
  • Rinse with DI water when complete.
  • Set KOR Software or the EXO Handheld Display to read the Specific Conductance in us/cm (Options>Units> Conductivity).

 

Temperature Test:

For improved confidence in temperature data, organizations have standard operating procedures (SOPs) that compare temperature readings with a trusted alternative at multiple points of reference in homogenous reference solutions.


Steps:

1. Compare the probe’s reading to a “traceable” temperature reference at room temperature. The temperature reading should be within the accuracy tolerance of the two devices.  (generally they will agree within 0.5C)

2. Test the temperature again in ice water and at an elevated temperature around 40 C. Again, accuracy should be within the tolerance of the two devices, mixing may be required to maintain a homogeneous solution.

3. If there are discrepancies between the temperature readings, contact our YSI technical support team at info@ysi.com or +1 (937) 767-2762 for further troubleshooting or replacement.

 

Conductivity Test:

To ensure high quality conductivity data, many monitoring groups take measurements in air, and record cell constants after every calibration. This allows them to easily track any changes in the sensor over time.

Steps:

1. Clean and then rinse probe thoroughly with DI water, and then use compressed air to remove all moisture from both conductivity cells. Be sure to use air filtered for oil, water and other particulates.

2. Measure the conductivity in air with the dry sensor, the SC reading should be ≤ 1.0 us/cm.

3. If the probe reads above 1.0 us/cm in air, thoroughly clean it once more and dry with compressed air before taking another measurement in air.

4. Next, calibrate the sensor using a standard no less than 1,000 us/cm to ensure the probe is reading accurately. After calibrating, check the cell constant; it should read 5.0-6.5 on EXO sensors.
Note: Be sure to follow typical calibration procedures. If you have any questions or concerns about calibrating conductivity probes, check out this short tutorial from EXO University.

5. If the conductivity reads high in air or the cell constant is outside of the stated range, contact our YSI technical support team at info@ysi.com for further troubleshooting or replacement.

 

YSI always recommends validating probe performance prior to extended monitoring. A little extra work up front can ensure you’re collecting the highest quality data for your monitoring project.

 

 

2 Responses to “Best Practices for QA/QC for EXO Conductivity/Temperature sensors.

Leave a Reply

Your email address will not be published. Required fields are marked *