Are there settings that need to be changed on the TL23 Turbidimeters out of box to use the included standards for calibration and verification?

Document ID

Document ID TE8281

Published Date

Published Date 12/20/2021
Question
Are there settings that need to be changed on the TL23 Turbidimeters out of box to use the included standards for calibration and verification?
Summary
Changes that need to be made in the TL23 settings to use the included standards for calibration and verification.
Answer
IQ/OQ requires verification after calibration using a 10 NTU standard. The TL23 turbidimeters are set with this as default for customers who require IQ/OQ. However, a 10 NTU standard is not included.

If IQ/OQ is required, the 10 NTU standard must be purchased separately (Product # 2659902).

Gelex Secondary Standards are included with the instrument for calibration verification for labs where IQ/OQ is not required. These standards are used to verify the calibration regularly, but the assigned value of the secondary standards needs to be reset after each calibration with primary standard. Because of this, it is not recommended to have “Verify after Cal” turned on when using the Gelex Secondary Standards. (See also: How do I use Gelex secondary standards?)

If IQ/OQ is not required and the 10 NTU standard is not needed, then before calibrating with the Stablcal® Primary Standards the following change is needed:
  1. From the home screen select "Verification" from the right hand menu.
  2. Select "Options".
  3. Select "Verification Set up".
  4. Select "Verify after Cal" and set to "Off".
From here the operator can continue calibration using the Stablcal® Primary Standards included with the instrument following the instructions in the User Manual without being required to verify at the end with a 10 NTU standard.

To use Gelex Secondary Standards for calibration verification (recommended and included), immediately after calibration with primary standards is complete, take a measurement on each Gelex Secondary Standard following the instructions from the User Manual and record the result for each standard.

Once the results for each selected standard is obtained, follow these steps to set the verification to be specific to the values obtained for the Gelex Secondary Standards specific to the current calibration:
  1. From the home screen select "Verification" from the right hand menu.
  2. Select "Options".
  3. Select "Verification Set up".
  4. Select "Verification Standards".
  5. Select the number of points. This should be equal to the number of non-Stray light Gelex standards that will be used for routine calibration verification (1-5).
  6. Highlight "Standard 1", and select "Edit".
  7. Select "Secondary Standard".
  8. Enter the recorded result from when that standard was measured following the calibration with primary standard and press “OK”.
  9. If the acceptance range needs to be changed that can be done (the default is 10%). Otherwise press "OK".
  10. Repeat steps 6-9 for each other standard that will be used for routine calibration verification.
  11. Select "OK" again and Close to return to Verification mode.
Hach recommends performing calibration verification daily, but the frequency can be set by the user. If the verification passes within the user set tolerance (default of 10% recommended) then the instrument does not need to be recalibrated with the Stablcal® Primary Standards. If it does not pass, then the instrument should be recalibrated with the Stablcal® Primary Standards.

After each calibration, the above process should be repeated to reassign the values for each Gelex Secondary Standard that is used for routine verification for the new calibration.

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