Regarding specific gravity, what does it tell you about a liquid and how does it affect firefighting strategy?

Regarding specific gravity, what does it tell you about a liquid and how does it affect firefighting strategy?

• A. It indicates density relative to water; liquids lighter than water float on it, heavier sink; affects spill control and foam use.
• B. It measures viscosity only.
• C. It measures color.
• D. It has no impact on firefighting.

Answer: (A)

Specific gravity is a measure of how dense a liquid is compared with water, so you learn right away whether it will float on water or sink. If a liquid is lighter than water, it rides on the surface and can spread as a slick across water and into drains or low spots. That surface behavior drives how you set up containment and apply foam: you’ll build surface barriers and use foam blankets designed to cover and cool the fuel, keeping it from spreading and vaporizing. If a liquid is heavier than water, it tends to sink or stay below the surface, which makes surface containment less effective and changes the approach—you may need to remove it from the bottom, use absorbents and pumps, and address pooling in depressions rather than simply damming a surface slick. The bottom line is that knowing whether a liquid floats or sinks helps you choose containment tactics and how foam interacts with the fuel to cool and separate it from air.