The document discusses cloud point, pour point, and oiliness as important properties of lubricating oils. The cloud point is the temperature at which an oil becomes cloudy upon cooling, while the pour point is when the oil stops flowing. Low cloud and pour points indicate an oil is suitable for cold conditions. Oiliness refers to an oil's ability to adhere to machine surfaces under pressure. Good lubricants have low cloud/pour points and high oiliness.

1. CLOUD POINT AND POUR
POINT
SEMINAR TOPIC:
ENGINEERING
CHEMISTRY
PRESENTED BY:
BARATH KUMAR .C

2. CLOUD POINT
When an oil is cooled slowly the temperature at which the
oil becomes cloudy in appearances is called its CLOUD POINT.

3. Cloud point

4. PERCENTAGE USE OF DIFFERENT METAL IONS FOR CLOUD POINT
EXTRACTION

5. POUR POINT
The temperature at which the oil ceases to flow or pour is
called its POUR POINT.

6. Pour point

7. SIGNIFICANCE
 Most of the petroleum based lubricating oils contain dissolved paraffin
wax and Asphaltic Impurities. When the oil is cooled these impurities
undergo solidification which cause jamming of the Machine. So the
cloud and pour points indicate the suitability of the lubricants in cold
condition. A good lubricant must have low cloud point and pour point.

8. DETERMINATION
 An oil is taken in a flat bottomed tube enclosed in an air jacket and it is cooled in a
freezing mixture (ice + CaCl2).
 Thermometers are introduced into the oil and freezing mixture. As the cooling takes place
via the air jacket temperature of the oil falls. The temperature at which the cloudiness
appears is noted as the Cloud point.
 The cooling is further continued. The temperature at which the oil does not flow in the
test tube for 5 seconds on tilting it to the horizontal position is noted as the pour point.
 A good lubricant should have low cloud point and pour point. Pour point of a
lubricating oil can be lowered by (a) Dewaxing (b) adding a pour point depressant.
 Example
Poly alkyl benzene called ‘para flow’ is a commonly used pour point
depressant.

9. COMBINATION OF CLOUD AND POUR POINT

10. OILINESS
 Oiliness is the capacity of a lubricating oil to stick
on to the surface of the machine parts under heavy
load or pressure

11. SIGNIFICANCE
• Lubricants which have high oiliness stay in between the
lubricated surfaces.
• When they are subjected to high load and pressure . But
lubricants with poor oiliness will be squeezed out of the
machine parts under this condition.

12. HOW TO IMPROVE OILINESS
 Mineral oils have poor oiliness where as vegetable and
animal oils have high oiliness .
 Hence oiliness of mineral oil is improved by adding
vegetable oils and higher fatty acids like oleic acid, Stearic
Acid , etc. A good lubricant should have good oiliness.