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Louver Area Formula:
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Louver area calculation determines the required free area of a louver based on airflow requirements and velocity. This is essential for proper ventilation system design and ensuring adequate airflow through building enclosures.
The calculator uses the louver area formula:
Where:
Explanation: The formula calculates the minimum required free area of a louver to handle a specific airflow at a given velocity without excessive pressure drop.
Details: Proper louver sizing is critical for maintaining building pressure balance, ensuring adequate ventilation, preventing water intrusion, and optimizing energy efficiency in HVAC systems.
Tips: Enter airflow in cubic feet per minute (cfm) and velocity in feet per minute (fpm). All values must be valid positive numbers. Typical louver velocities range from 300-800 fpm depending on application.
Q1: What is the difference between free area and overall area?
A: Free area refers to the open space for airflow, while overall area includes the frame and blade structure. Free area is typically 35-60% of the overall area.
Q2: What velocity should I use for louver selection?
A: Standard practice recommends 500 fpm for intake louvers and 800 fpm for exhaust louvers to balance pressure drop and noise considerations.
Q3: How does rain defense affect louver area?
A: Rain defense louvers typically have lower free area percentages (35-45%) compared to standard louvers (50-60%), requiring larger overall dimensions for the same airflow.
Q4: Should I include safety factors in my calculation?
A: Yes, it's recommended to add a 10-20% safety factor to the calculated area to account for manufacturing tolerances, fouling, and future system changes.
Q5: How does louver orientation affect performance?
A: Horizontal louvers generally provide better rain defense, while vertical louvers may offer slightly better airflow characteristics in certain applications.