- Method ASTM D1500
- Repeatability .5 color unit
- Reproducibility 1 color unit
- Blending non-linear
- Additive Correction No
This purpose of this test method is the visual determination of the color of a wide variety of petroleum products such as diesel fuel oils, heating oils, lubricating oils and petroleum waxes. The color scale ranges from 0.5 to 8.0.
This method is performed by using a colorimeter. It is basically a box that contains a light bulb, sample chamber, color standard, and viewing port. The sample poured into a glass jar and placed into the unit. On the other side of the chamber is a glass jar filled with distilled water and the glass color standard disk. The technician will then look through the view port and will attempt to find an exact match using the color disc. If an exact match is not able to be found and the sample falls in between two numbers, the higher reading of the two is reported. The lower the number the lighter the product color is. A bright yellow ULSD usually runs around 0.5 while a dark LCO can extend through the range up to an 8.0.
This scale is used to determine quality characteristics of products due to its ease of use. For example the typical ULSD that runs 0.5 suddenly shows up as a 1.5 on the scale can indicate issues with stability or the products refinement. This will only give a general idea of an issue and further investigation should be initiated to determine the root cause.