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Lab Methods

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Sediment and Water by Centrifuge

  • Method ASTM D1796
  • Repeatability Variable, see method
  • Reproducibility Variable, see method
  • Blending non-linear
  • Additive Correction No

Describes the laboratory determination of water and sediment in fuel oils in the range from 0 to 30 % volume by means of the centrifuge procedure. This is applicable to most products except for products containing alcohols or other compounds that mix with water. In those cases water by distillation D95 or water by karl fisher E206 or E1064 can be used.

This method is performed by first mixing the sample 50/50 with water saturated toluene in a centrifuge tube and heating it. Heating the sample is used to break down any paraffin waxes within and prevent false sediment readings. The sample is then shaken before being placed in the centrifuge to spin. Once the tube is spun, the water and sediment which are heavier than the sample will be forced to the bottom of the tube. After this is complete the tube is removed then flipped vertical to ensure an accurate reading of the sediment and water since the sediment can be the same color as darker residual fuels.

Sediment and water can cause issues in all types of fuels. First off when clients are buying and selling crude oil the BS&W results are backed out of the final volumes. This is because most clients only pay for the actual product. Second when free water drops out of the sample it can cause corrosion issues in storage tanks, fuel tanks, lines, pumps, etc. Third the sediment in the product can accumulate and clog up pumps, filters, burners etc. which can lead to mechanical
damage and/or failure.