The boiling point is the temperature at which a substance passes from the liquid to the gaseous state. If the boiling point is defined as the temperature at which a substance's liquid and gaseous phases are in thermodynamic equilibrium, the boiling point is then identical with the condensation point. With the boiling point being heavily dependent on pressure, the reference pressure should always be specified. In the literature there are often slight differences between values given for the "standard" boiling point; this is owed to non-uniform methods of determination and

reference pressures: 1 bar or 760 mm Hg (= 1.01325 bar). Many media do not have an exactly determinable boiling point, but a boiling range. In addition to specifying this range, it is customary to state the initial boiling point. In the case of media, which undergo a chemical change at a specific temperature, one speaks of the decomposition temperature. Specification of the boiling or decomposition point makes it easier to select the right mechanical seal and enables due reference to be made to any necessary supplementary measures.