When would the use of a 5000 fpm exhaust duct velocity be justified in a ventilation system?

The justification for using a 5000 feet per minute (fpm) exhaust duct velocity in a ventilation system primarily revolves around the need to prevent the settling of airborne particles. Higher velocities in exhaust ducts are effective in keeping particulate matter suspended in the air rather than allowing it to settle on surfaces. This is important in industrial settings where dust, fumes, or other contaminants might be present. By maintaining a high airflow velocity, the system is better able to capture and remove these particles from the workspace, thereby improving air quality and reducing health risks for workers.

While other options might seem relevant in certain contexts, they do not directly address the primary reason for high exhaust duct velocities. For instance, reducing noise levels or improving air circulation are important factors in ventilation design, but they do not necessitate such a high exhaust velocity. Similarly, while cooling purposes can be a consideration in some ventilation strategies, achieving cooling is not the main aim of setting a high duct velocity. The primary focus in this context is to control airborne contaminants effectively.