What percentage of free air is required for metal louvers?

The correct percentage of free air required for metal louvers is typically 75%. This requirement ensures that there is sufficient airflow through the louvers to effectively ventilate an area, allowing for adequate exhaust or intake as needed. The design of metal louvers inherently restricts some airflow due to the physical structure and materials used, which is why a higher percentage is necessary compared to other types of ventilation openings.

The 75% free air allowance accounts for these restrictions while still providing optimal performance. When designing ventilation systems, ensuring the right amount of free air is crucial for maintaining air quality and preventing issues such as moisture buildup or insufficient air exchange.

With lower percentages like 25% or 50%, there may not be enough airflow, which could lead to inadequate venting and potential health or structural problems over time. A requirement of 100% free air is not practical for louvers, as it would imply no obstructions, which defeats the purpose of having a physical louver structure in place.