What units are commonly used to express fuel flow in gas turbines?

• A. Gallons per minute.
• B. Liters per second.
• C. Barometers per second.
• D. Pounds per hour or kilograms per second.

Answer: (D)

Fuel flow is measured as a mass flow rate in gas turbines. This approach directly represents how much fuel mass is entering the combustor per unit time, which is what governs the energy available for combustion. Because fuel density can change with temperature and composition, using mass flow keeps comparisons and calculations consistent and independent of those density variations. That’s why common practice uses pounds per hour or kilograms per second.

Volumetric units like gallons per minute or liters per second are tied to the fuel’s density, so the same volume can contain different masses under different conditions. That makes them less reliable for predicting the actual energy input. Barometers per second isn’t a meaningful unit for flow at all, since a barometer measures pressure, not how much fuel is moving.

So the most practical and consistent way to express fuel flow in gas turbines is the mass flow rate—pounds per hour or kilograms per second.