Volumetric Flow Rate (Q) is defined as a measurement of air flowing through a point in the system.

Volumetric Flow Rate (Q) is defined as a measurement of air flowing through a point in the system.

• A. The potential energy of the ventilation system
• B. The area of cross-section of duct
• C. A measurement of air flowing through a point in the system
• D. The velocity pressure of the air

Answer: (C)

Volumetric flow rate describes how much air passes a point per unit time. It’s a rate, not energy, not just the duct’s cross-section, and not velocity pressure. When air moves through a duct, the volume flowing per second depends on both the duct area and how fast the air is moving, so it’s essentially the product of area and velocity (Q ≈ A × v for a uniform velocity profile). In practical terms, Q is measured in units like m^3/s or CFM, and mass flow rate is related by ṁ = ρ × Q. The other ideas—potential energy, the area alone, or velocity pressure—do not describe the amount of air flowing per unit time, so they don’t define volumetric flow rate.

Volumetric flow rate describes how much air passes a point per unit time. It’s a rate, not energy, not just the duct’s cross-section, and not velocity pressure. When air moves through a duct, the volume flowing per second depends on both the duct area and how fast the air is moving, so it’s essentially the product of area and velocity (Q ≈ A × v for a uniform velocity profile). In practical terms, Q is measured in units like m^3/s or CFM, and mass flow rate is related by ṁ = ρ × Q. The other ideas—potential energy, the area alone, or velocity pressure—do not describe the amount of air flowing per unit time, so they don’t define volumetric flow rate.