Which formula would you use to calculate the Btu/lb. heat content of fuel oil?

The correct formula for calculating the Btu/lb. heat content of fuel oil is derived based on the American Petroleum Institute (API) gravity of the oil at 60°F. The specific formula chosen, which adds a base value to a product of the API gravity, has been established through industry standards for predicting the energy content of fuel oils.

Option B states: "17,687 + 57.7 x API at 60F." This formula takes into account the density of the oil and its specific characteristics, allowing for an accurate approximation of its heat content. The base value of 17,687 Btu/lb is suitable for the typical range of fuel oils, while the multiplication factor of 57.7 accounts for the variations in energy content with changing API gravity.

This calculation is important because knowing the Btu/lb. heat content is essential for understanding how much energy can be extracted from a certain volume or weight of fuel oil, which is crucial in various applications such as powering boilers or engines efficiently.

Other formulas provided in the options characterize different relationships between API gravity and heat content, but do not align with the established industry standard as accurately as option B does for fuel oil, making it the preferred choice in this context.