What is the effect of a temperature rise on SG (specific gravity) in this context?

• A. Increases
• B. Decreases
• C. No Change
• D. Doubles

Answer: (B)

Increasing temperature causes densities to drop. Specific gravity is the ratio of the liquid’s density to the density of water at the same temperature, so as both densities fall, the liquid’s density typically falls more quickly because hydrocarbons expand more with heat than water does. This means the SG value decreases as temperature rises. In practice, fuels are often referenced at a standard temperature (like 60°F); if the fuel is warmer, the observed SG will be lower unless a temperature correction is applied.