What can cause a 'Process Head Open' Error on a TU5300/TU5400 turbidimeter?

Document ID

Document ID TE12900

Published Date

Published Date 05/06/2021
What can cause a 'Process Head Open' Error on a TU5300/TU5400 turbidimeter?
TU5300/TU5400 Process Head Open Error
The 'Process Head Open' error is typically caused by either the process head having been removed from the base or the process head has not been locked correctly into the base. 
If you continue to get the error when the process head is correctly installed it may be an issue with the magnet in the lid.  This magnet is what the sensor uses to detect correct installation of the process head.
Follow the below instructions to check this magnet
  • Unscrew all 3 nuts on the process lid -
  • Remove the smaller top section from the lid and flip it over to see the magnet
  • If the magnet isn't secure or if there is any kind of build-up or corrosion you may need to replace that section of the lid
  • Part number LZY919 is shown below and should fix any magnet issues

If the magnet in the process lid looks to be intact, please contact the Hach service team for further evaluation and repair.

See the following links and articles for more information on TU5300/TU5400 errors

User ManualTU5300 sc/ TU5400sc EPA version
How can TU5300sc or TU5400sc communicate when there's an instrument error?


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