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Lab Methods

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Haze Rating

  • Method ASTM D4176
  • Repeatability 1 number
  • Reproducibility 2 numbers
  • Blending non-linear
  • Additive Correction Yes

In this test method there are two procedures for estimating the presence of suspended free water and solid particulate contamination in distillate fuels having an ASTM color of 5 or less and distillation end points below 400°C.

For Procedure 1 approximately 900 mL of fuel is placed into a clear, glass, 1-L jar and is visually examined for clarity. The sample is then swirled and examined for visual sediment or water drops below the vortex. For this procedure, the results reported will be stated as “clear and bright” or “fail”. The failing result should also list why it failed. This can also be expanded to include free water or particulates.

For Procedure 2 approximately 900 mL of fuel is placed into a clear, glass, 1-L jar and is visually examined for clarity. Fuel clarity is rated by placing a standard bar chart behind the sample and comparing its visual appearance with the standard haze rating photos. The sample is then swirled and examined for visual sediment or water drops below the vortex. The method is typically run at a specified temperature depending upon client or pipeline spec. It is rated on a scale of 1 to 5 (1 being the clearest and 5 the haziest).

This method gives a quick indication whether the fuel is clean or may have issues that need to be addressed.