PhosLube – Base Oils Boiling Point Analysis
The Initial Boiling Point (IBP) is the temperature at which the first drop of condensed vapor appears in a distillation test. Distillation tests check the volatility of an oil, which is the measurement of how rapid the oil evaporates. Distillation tests are used on light crude oils for new product determination purposes. Unlike some chemical compounds that will boil at a certain temperature, petroleum based distillates are quite different. Petroleum is made up of different fractions that boil at different temperatures. A distillation range is determined using the upper and lower limits of the boiling points of each separate fraction. Distillation range can also be determined using the difference in degrees between the IBP and the end point (EP). IBP’s may vary depending on contamination or poor fractionation during the refining process. An IBP over 400°F is classified as being too high. Boiling point analysis will determine the IBP and the other temperature fractions that follow.
- 10% Boiling Point: The next temperature fraction following the IBP is the 10% point. This temperature reading is take after 10% of the total volume of oil distills off. Some companies will measure at the 5% point instead, depending on preference. Typically distillation points between the 20% and 80% fractions have no significance, although sometimes the 50% point is used to determine the variations between the IBP and the EP.
- 90% Boiling Point: The 90% point and the EP are important. Again, these points may vary depending on contamination or oils being improperly refined. If these points end up being high (more-so for the EP) there is a good chance the oil is contaminated or there is a high carbon residue. Some companies will measure at the 95% point instead, depending on preference.