Cloud and Pour Point Test of Petroleum Oils

Vocabulary cards covering key terms, apparatus, procedures, and concepts related to the Cloud and Pour Point Test of lubricating and fuel oils.

Pour Point

The lowest temperature at which movement of a petroleum test specimen is observed under prescribed test conditions.

Cloud and Pour Point Test

Laboratory procedure used to determine the temperatures at which oil first forms wax crystals (cloud point) and ceases to flow (pour point).

Black Oil

Lubricant containing asphaltic materials; used in heavy-duty equipment where extra adhesiveness is required.

Cylinder Stock

Heavy lubricant for independently lubricated engine cylinders, steam engines, and air compressors; also lubricates valves and parts in the cylinder area.

Residual Fuel

Heavy liquid fuel consisting of the bottoms remaining after crude-oil distillation or thermal cracking.

Cork (Stopper)

Cork fitted with a central bore to hold the thermometer and seal the test jar.

Jacket

Metal, flat-bottomed cylinder that surrounds the test jar; immersed in a cooling bath to control sample temperature.

Disk

6 mm thick cork or felt insert placed at the bottom of the jacket to cushion the test jar.

Pour Point Depressant

Chemical additive that inhibits wax crystal growth, lowering an oil’s pour point and improving low-temperature flow.

Paraffin Wax Crystals

Solid wax network that forms during cooling; its rigidity determines the pour point when oil stops flowing.

cloud point

—in petroleum products and biodiesel fuels, the temperature of a liquid specimen when the

smallest observable cluster of wax crystals first appears upon cooling under prescribed conditions.

biodiesel

—a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal

fats, designated B100.

Charge volume

—the volume of the specimen, 100 mL, charged to the distillation flask

Decomposition

the pyrolysis or cracking of a molecule yielding smaller molecules with lower boiling points than

the original molecule. Characteristic indications of thermal decomposition are evolution of fumes and erratic temperature readings that

usually decrease after any attempt is made to adjust the heat.

Decomposition point

—the corrected thermometer reading that coincides with the first indications of thermal decomposition of the

liquid in the flask. The decomposition point, as determined under the conditions of this test method, does not necessarily correspond

to the decomposition temperature inother applications.

Dry point

—the corrected thermometer reading that is observed at the instant the last drop of liquid(exclusive of any drops or film of

liquid on the side of the flask or on the temperature sensor), evaporates from the lowest point in the distillation flask.The end point (final

boiling point), rather than the dry point, is intended for general use.

refers to a substance's tendency to vaporize or turn into a gas at a given temperature and pressure.A substance with high ——- readily changes from liquid to gas, while a substance with low ———- is more likely to remain in a liquid or solid state.