General
The cloud point of a petroleum oil is an index of the lowest temperature of its utility for certain applications. Cloud point is the temperature at which a cloud of wax crystals first appears in a liquid when it is cooled under conditions prescribed in this test method. Thi.s test method covers only petroleum oils which are transparent in layers 38 mm (1 1/2 in.) in thickness, and with a cloud point below 49°C
(120 °F). The cloud point is usually higher than the pour point
(Test Method D 97).
Test:
The sample is first heated to a temperature above the expected cloud point and then cooled at a specified rate and examined periodically. The temperature at which haziness is first observed at the bottom of the test jar is recorded as the cloud point.
Precision:
|
|
Repeatability |
Reproducibility |
|
Distillate Oils |
2°C (4°F) |
4°C (8.°F) |
|
Biodiesel blends in diesel |
2°C (10.°F) |
3.2°C (10.4°F) |