THIS CHAPTER INCLUDES A DISCUSSION ON THE details of distillation measurement test methods for petroleum products performed at reduced pressure. The test methods covered are ASTM D2892-03 “Standard Test Method for Distillation of Crude Petroleum (15 Theoretical Plate Column)” [1], D5236-03 “Standard Test Method for Distillation of Heavy Hydrocarbon Mixtures (Vacuum Potstill Method)” [2], and D1160-03 “Standard Test Method for Distillation of Petroleum Products at Reduced Pressure” [3].