Cloud point and pour point are two important properties of liquids that determine how they behave in cold temperatures. Cloud point is the temperature at which small crystals of impurities first appear in a liquid, while pour point is the temperature at which the liquid becomes too thick to flow. These properties are particularly important for fuels and lubricants, as they can affect their performance and handling in cold weather. Understanding cloud and pour point can help ensure that the liquids you use in your equipment or vehicles perform well even in freezing temperatures.

1. Chemistry
Cloud
&
Pour
Point of Lubricating Oil

2. Points
1. Definition
2. Factor affecting cloud and pour point
3. Importance of maintaining cloud and
pour point
4. Determination of cloud point
5. Determination of pour point

3. Cloud
The temperature at which a lubricating oil
begins to form cloudy suspensions due to
the presence of wax crystals.
Point

4. Pour
Point
The pour point of a lubricating oil is the
temperature at which the oil ceases to
flow or pour .

5. Factors Affecting of Cloud and Pour Point
•Temperature: As the temperature drops, the
wax crystals in the oil will begin to form, raising
the cloud point and lowering the pour point.
•Impurities: Impurities such as water, dust, or
other contaminants can affect the cloud and
pour point of lubricating oil.
•Composition: The chemical composition of
lubricating oil, including the types and amounts
of additives and base oils, can affect its cloud
and pour point.
•Viscosity: As viscosity increases, the pour point
is likely to decrease.
•Shear rate: The rate at which the oil is flowing
can affect the pour point.

6. Importance of Maintaining Cloud and
Pour Point
•Performance: Lubricating oils with high cloud
points and low pour points will not perform well
in cold temperatures, which can lead to poor
equipment performance and increased wear and
tear.
•Equipment longevity: Lubricating oils that do not
flow well in cold temperatures can cause
equipment damage, leading to costly repairs and
reduced equipment lifespan.
•Safety: Lubricating oils that do not perform well
in cold temperatures can also increase the risk
of accidents and equipment failure in certain
industries such as aviation and marine.

7. Cloud &
Pour
Point
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8. Thermometer
Cork
Cooling bath
Gasket
Jacket
Test Jar
Disk
To determine Cloud
Point
A sample of the lubricating oil is poured into a test
Jar and cooled in progressive steps. When
Inspection first reveals a distinct cloudiness or
haze at the bottom of the test jar, the temperature
is recorded as the cloud point

9. To determine Pour pointThermometer
Cork
Cooling bath
Gasket
Jacket
Test Jar
Disk
A sample of oil is cooled in flat-bottomed tube under
Specified conditions; the temperature is observed
Increments of 5 degree F until no movement is
Observed at the surface of the oil when the tube is
Held in a horizontal position for 5 sec.
This temperature is recorded as the solid point.
By definition the pour point is 5 degree F
above this temperature.

10. Thanks!
Reference
1. All images are ai generated by midjourney.
2. Books- Engineering Chemistry by- Shashi Chawla