Importance of Testing DEF to Spec Case Study


This customer took the right precautions and purchased the proper Misco Refractometer (Models DEF 201 & DEF 202 are both approved) Brenntag recommends for testing loads of Diesel Exhaust Fluid (DEF). When receiving a recent bulk delivery from Brenntag, the refractometer reading showed the DEF was not within ISO specifications.


The next delivery, the Brenntag driver asked to see how the customer was testing the fluid. He realized that they were reusing the testing tools instead of properly wiping the refractometer clean after each use. Our driver told them to use proper cleaning cloths and new sample taking tools for each load of DEF. To make sure the fluid was being tested correctly, he tested the load himself which proved the fluid was indeed within spec; this was backed also by the Certificate of Analysis (CoA) the driver had in his possession.

How to Properly Use a Refractometer

  • Place a couple drops of DEF into the stainless-steel well.
  • Press the button to initiate the reading.
  • Within seconds, the urea concentration will be displayed on the LCD screen.
  • Wipe clean the refractometer of any DEF residue after each use.

What Brenntag Offers Clients Like This...

Brenntag provides quality product and assistance on how to properly test the product to spec.

Company Type: Fuel Distributor

Geographical Location: South Texas

Size: 6 locations, over 70 employees

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While working through this challenge, the customer was taught how to properly test for contamination of the product during delivery of each load. The customer was reassured of the quality product Brenntag delivers and is confident they’re distributing a quality product to their customer base.


Testing Diesel Exhaust Fluid (DEF) is important to do duringmultiple steps from creation to delivery. Upon arrival at eachBrenntag terminal, every load of ultra pure DEF must undergoan extensive testing process to assure consistent quality.Not properly testing DEF can result in:

  • Voided vehicle warranties
  • Premature catalyst deactivation
  • Detrimental effects to SCR catalyst performance
  • Lower fuel economy
  • Fouled pre-filters and injector nozzles