IP 389 Determination of Wax Appearance Temperature (WAT) of Middle Distillate Fuels by Differential Thermal Analysis (DTA) or Differential Scanning Calorimetry (DSC)
Middle distillate fuels including fuel oil, kerosene and diesel oils are frequently transported through pipelines and tubing. At low temperatures, such as those in colder climates, wax in these mixtures may precipitate or cause gelling, thus impeding flow and potentially clogging lines. This test determines the temperature at which wax appears in the fuel, which is an indication of the lowest temperature at which the fuel may safely be pumped.
The sample is placed in a DSC and slowly cooled. The wax appearance temperature is determined from the experimental trace and reported in °C.