What is the minimum velocity allowed in an exhaust hood duct system?

In ventilation systems, particularly for exhaust hood duct systems, maintaining an appropriate air velocity is crucial for effective capture and removal of contaminants, heat, and odors. The minimum velocity specified for exhaust hood duct systems is typically set to ensure that air movement is strong enough to effectively pull cooking fumes, smoke, and other particulates away from the cooking surface into the ductwork.

Selecting a minimum velocity of 500 feet per minute ensures that there is sufficient air movement to capture and remove airborne pollutants efficiently. This velocity reduces the likelihood of contaminants escaping into the kitchen or dining area, thereby enhancing indoor air quality and meeting safety standards.

Additionally, this specification helps in overcoming the potential resistance and turbulence that can occur in duct systems, ensuring that airflow remains consistent and effective throughout the system. Lower velocities may not provide adequate capture of cooking emissions, which can lead to increased indoor air pollution and associated health risks.