Specific gravity of fuel

 Specific gravity of a fuel is a dimensionless quantity that compares the density of the fuel to the density of water at a standard temperature and pressure. It provides a measure of how dense the fuel is relative to water and is often used in industries such as petroleum, automotive, and aviation to characterize and classify fuels.

The specific gravity of a fuel is calculated using the following formula:

$\text{Specific gravity}=\frac{\text{Density of fuel}}{\text{Density of water at standard conditions}}$

Typically, the density of water at standard conditions (4°C or 39.2°F and 1 atm pressure) is taken as 1000 kg/m³ or 1 g/mL. Therefore, the specific gravity of water is 1.

If the density of the fuel is given in units of kilograms per cubic meter (kg/m³), then the specific gravity will be numerically equal to the ratio of the density of the fuel to 1000 kg/m³. Similarly, if the density is given in grams per milliliter (g/mL), the specific gravity will be numerically equal to the ratio of the density of the fuel to 1 g/mL.

For example, if the density of a fuel is 750 kg/m³, then the specific gravity would be:

$\text{Specific gravity}=\frac{750\text{kg/m³}}{1000\text{kg/m³}}=0.75$

Similarly, if the density of the fuel is 0.75 g/mL, then the specific gravity would be:

$\text{Specific gravity}=\frac{0.75\text{g/mL}}{1\text{g/mL}}=0.75$

The specific gravity of a fuel provides a convenient way to compare its density to that of water and is often used in fuel specifications, regulations, and standards. It helps in classifying fuels, determining their suitability for specific applications, and calculating quantities for blending or mixing different fuels.