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Lesson 5 – Interpreting Differences Between DPD and Your Kuntze Analyzer (1:38)

Watch the video to learn how to interpret DPD results and when a new calibration of your Zirkon DIS® sensor is necessary.

Interpreting Tolerances

Many drinking water applications follow tolerances outlined in USEPA 334.0, which states that “[analyzer] reading must be within ± 0.1 mg/L or ± 15% (whichever is larger) of the grab sample measurement.”

To visualize this, we show reference measurements with a green circle with error bars on our graphs. Here is an example calculation using the ± 15% tolerance:

DPD value = 2.00 ppm

Tolerance = 0.15 x 2.00 ppm = 0.30 ppm

Accepted range is 1.70 to 2.30 ppm.

  • 2.30 ppm
  • 2.00 ppm
  • 1.70 ppm

To be compliant with USEPA 334.0, the analyzer measurement would have to be between 1.70 ppm and 2.30 ppm for a DPD measurement of 2.00 ppm using a ± 15% tolerance.

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