The principle of determining the chromaticity of petroleum products is to compare the color depth of the sample to be tested with a standard color plate using colorimetric method, and determine the degree of color depth of petroleum products by comparing the chromaticity values.
The specific measurement process is as follows: place the sample to be tested and the standard color plate on the colorimeter, irradiate the light source on the standard color plate, and generate standard brightness light on its surface. At the same time, the reflected light of the tested sample can also be illuminated on the colorimeter after passing through a specific optical path. The colorimeter detects the spectral characteristics of the reflected light generated by the standard color plate and test sample through optical sensors, and then calculates the color difference between the two to obtain the chromaticity value of the test sample, reflecting the color depth of the sample.
Usually, the colorimetric determination results of petroleum products are expressed in international standard units - colorimetric value (Pt Co). The higher the chromaticity value, the darker the color of petroleum products. On the contrary, the lower the chromaticity value, the lighter the color of petroleum products.