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Volumetric Flow Rate Equation:
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Volumetric flow rate (Q) is the volume of fluid that passes through a given cross-sectional area per unit time. For air flow, it represents the volume of air moving through a duct, pipe, or opening in cubic meters per second.
The calculator uses the fundamental flow rate equation:
Where:
Explanation: The equation calculates how much volume of air passes through a specific area when moving at a given velocity over one second.
Details: Accurate flow rate calculation is essential for HVAC system design, ventilation planning, industrial process control, and ensuring proper air circulation in buildings and mechanical systems.
Tips: Enter cross-sectional area in square meters and velocity in meters per second. Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is the difference between volumetric and mass flow rate?
A: Volumetric flow rate measures volume per time (m³/s), while mass flow rate measures mass per time (kg/s). They are related by density: mass flow = volumetric flow × density.
Q2: How do I measure cross-sectional area for irregular shapes?
A: For circular ducts, use A = πr². For rectangular ducts, use A = width × height. For irregular shapes, divide into regular sections or use specialized measurement tools.
Q3: What are typical air velocities in ventilation systems?
A: Typically 2-5 m/s in main ducts, 1-3 m/s in branch ducts, and 0.5-1 m/s in diffusers, depending on the application and noise requirements.
Q4: Does temperature affect volumetric flow rate?
A: Temperature affects air density but not the volumetric flow rate calculation directly. However, for mass flow rate or when comparing at different conditions, temperature correction may be needed.
Q5: When is this calculation most accurate?
A: This calculation assumes uniform velocity profile across the entire cross-section. In reality, velocity varies across the duct, so average velocity measurements provide the best results.