• Smoke Point: The smoke point is a test that measures the burning qualities of kerosene and jet fuel. It is defined as the maximum height in mm, of a smokeless flame of fuel. Smoke point is related to the hydrocarbon composition of kerosene—it is highest with paraffins, considerably lower with naphthenes and very much lower with aromatics.

  • Aniline Point:

    • The lowest temperature at which an equal volume mixture of the petroleum oil and aniline are miscible is the aniline point.

    • Since aniline is an aromatic compound, a petroleum fractions with high aromatic content will be miscible in aniline at ambient conditions. However, if the oil has more paraffins, it will require a higher temperature and thus higher aniline point in order to be miscible in aniline.

    • This property is important for the specifications of diesel fuels.

    \[\text{High Aniline Point} \Longrightarrow \text{Paraffinic} \Longrightarrow \text{High Diesel Index} \Longrightarrow \text{Good ignition quality}\]

  • Reid Vapor Pressure:

    • The Reid vapor pressure (RVP) is frequently used as an indication of volatility of liquid hydrocarbons. The RVP of a product is the vapor pressure determined in a volume of air four times the liquid volume at 37.8\(^\circ\)C (100 \(^\circ\)F).

    • This property measures the vapor-lock tendency of gasoline.

    • It also indicates the explosion and evaporation hazards of the fuel.

  • Flash Point: It is the lowest temperature at which application of test flame causes vapor to ignite. It differs from autoignition temperature because in the latter there is no source of ignition.

    • It is measured by Cleveland closed cup and Pensky Martin open cup apparatus.

    • It indicates the explosive range of a fuel.

  • Fire Point: It is the temperature at which vapors of the flammable liquid continue to burn even after removal of ignition source.

    It is typically 5–10\(^\circ\)C more than flash point.