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Velocity Formula:
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Velocity in a duct refers to the speed at which air flows through a ventilation or air conditioning duct. It is a critical parameter in HVAC system design and analysis, measured in feet per minute (fpm).
The calculator uses the velocity formula:
Where:
Explanation: The formula calculates how fast air is moving through a duct by dividing the volume of air flowing per minute by the cross-sectional area of the duct.
Details: Proper velocity calculation is essential for designing efficient HVAC systems, ensuring adequate air distribution, minimizing noise, and preventing energy waste through excessive pressure drops.
Tips: Enter flow rate in cfm and area in ft². Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is a typical velocity range for HVAC ducts?
A: For main ducts, typical velocities range from 1000-2000 fpm; for branch ducts, 600-900 fpm; and for diffusers, 150-300 fpm.
Q2: Why is velocity important in duct design?
A: Proper velocity ensures efficient air distribution, minimizes noise, reduces energy consumption, and prevents issues like air stagnation or excessive pressure drops.
Q3: How do I measure duct area?
A: For rectangular ducts: width × height. For circular ducts: π × (diameter/2)². Convert all measurements to feet before calculating.
Q4: What happens if velocity is too high?
A: Excessive velocity can cause noise problems, increased pressure drop, higher energy consumption, and potential vibration issues in the duct system.
Q5: Can this calculator be used for liquid flow in pipes?
A: While the formula is similar, liquid flow calculations typically use different units (gpm instead of cfm) and may require additional factors for viscosity and pipe roughness.