• Boiling Point Curves:

    • ASTM distillation and TBP distillation characterize the volatility of petroleum fractions and crude oils. Both are batch distillation methods which differ mainly in the degree of fractionation obtained during distillation.

    • ASTM Distillation: This is essentially a batch distillation with one equilibrium stage and no reflux and minimum separation of the components of the fractions. The temperature of the rising vapors is recorded at specific interval of the collected distillates.

    • True Boiling Point (TBP) Distillation: It is performed in columns with 15 theoretical plates or equilibrium stages and a reflux ratio of 5. Data from TBP distillation provides more detailed characterization of the volatility of crude oil or petroleum fraction.

    • Since the degree of separation for a TBP distillation test is much higher than that of the ASTM distillation test, its initial boiling point is lower and its end point is higher than those of the ASTM test.