What is the Difference Between Cloud Point and Pour Point?

The key difference between cloud point and pour point lies in their temperature values and the physical properties of a liquid fuel that they describe:

• Cloud Point: This is the minimum temperature at which the first crystal formation starts, typically referring to the formation of wax crystals in diesel or biowax in biodiesels. The presence of solidified waxes thickens the oil and can clog fuel filters and injectors in engines. Cloud point is important for fuel oils and indicates the tendency of the oil to plug small orifices or filters at cold operating temperatures. Comparatively, cloud point has a higher value (high temperature).
• Pour Point: This is the minimum temperature below which a liquid loses its flow characteristics. Pour point refers to the lowest temperature at which a liquid fuel can still flow and is important for lubricating oil and other applications where flow is critical. It is the temperature at which a liquid becomes semi-solid and loses its flow characteristics. Comparatively, pour point has a lower value (low temperature).

In summary, cloud point is related to the formation of wax crystals and their impact on fuel filters and engine components, while pour point is related to the flow characteristics of a liquid fuel. Cloud point occurs at a higher temperature, and pour point occurs at a lower temperature.

Comparative Table: Cloud Point vs Pour Point

The cloud point and pour point are important physical properties of liquid fuels. Here is a table summarizing the differences between them:

In summary, the cloud point mainly evaluates the high-temperature stability of oil products, while the pour point mainly evaluates the low-temperature performance of oil products.