- Method ASTM D156
- Repeatability 1 color unit
- Reproducibility 2 color units
- Blending non-linear
- Additive Correction No
This test method covers the determination of the color of refined oils such as undyed motor and aviation gasoline, jet propulsion fuels, naphtha and kerosene, and, in addition, petroleum waxes and pharmaceutical white oils.
This color scale is mostly used for naphtha, jet, and other oils that are too light to be rated by the D1500 ASTM color scale (which applies to mostly diesel and lco products). The apparatus has and eyepiece with two long tubes attached below with a light reflecting off a mirror angled up into the tubes on the bottom. One tube contains colored glass disc standards at 0.5/1/2. The other tube is filled with sample. The technician will then look into the eyepiece and slowly empty the sample tube until the sample tube intensity matches the standard tube. At this point the technician will use the depth of the oil and number of standard glass disc to convert the reading into a number that ranges from -16 to +30.
Color is important because it can show if a product has been contaminated or thermally degraded. It is a comparison so the product must be run at its origin otherwise you will not be able to determine this. Be aware though even if a product is off in color it may not affect the actual performance of the fuel.