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Flammable and Combustible Materials Flashcards

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  1. Under NFPA 30, a Class IA flammable liquid is characterized by:

    Answer: A flash point below 73°F and a boiling point below 100°F

    Class IA liquids (e.g., diethyl ether, pentane) have a flash point below 73°F (22.8°C) AND a boiling point below 100°F (37.8°C), making them the most volatile NFPA 30 category.

  2. Which of the following petroleum products has the HIGHEST flash point?

    Answer: Residual fuel oil No. 6 (approx. 150°F+ / 66°C+)

    Residual fuel oil No. 6 (Bunker C) has the highest flash point of the common petroleum products listed, typically above 150°F, classifying it as a combustible liquid under NFPA 30.

  3. Acetylene (C₂H₂) is especially hazardous in marine environments because:

    Answer: It has an extremely wide flammable range of 2.5% to 100% and can decompose explosively under pressure

    Acetylene's flammable range extends from 2.5% to 100% by volume in air, and it can decompose explosively when pressurized above 15 psi, making it uniquely hazardous for shipboard welding operations.

  4. The autoignition temperature (AIT) of a flammable substance is best described as:

    Answer: The minimum temperature at which a substance ignites spontaneously without any external ignition source

    AIT is the minimum temperature at which a fuel-air mixture will self-ignite without a spark or flame; exceeding the AIT of a vapor in a hot tank or near hot equipment can cause spontaneous ignition.

  5. Class II combustible liquids under NFPA 30 have flash points in the range of:

    Answer: At or above 100°F (37.8°C) but below 140°F (60°C)

    NFPA 30 Class II combustible liquids (e.g., diesel fuel, heating oil) have flash points from 100°F (37.8°C) up to but not including 140°F (60°C).

  6. "Sour" petroleum cargo is more hazardous than "sweet" crude because:

    Answer: It contains hydrogen sulfide, which is both highly toxic and flammable

    Sour crude and sour petroleum products contain hydrogen sulfide (H₂S), which has an IDLH of 50 ppm, is flammable (4.3%–46% LEL/UEL), and can be rapidly incapacitating, adding a toxic hazard on top of fire risk.

  7. The Reid Vapor Pressure (RVP) of a petroleum cargo is important to a Marine Chemist because:

    Answer: Higher RVP indicates greater tendency to generate flammable vapors at ambient temperatures, representing a higher fire and explosion risk

    RVP is a measure of a liquid's evaporation tendency; cargoes with high RVP (like summer-blend gasoline) generate substantial vapor at ambient temperatures, increasing the flammability hazard in tanks and surrounding areas.