What is the term for the pressure difference that facilitates the flow of air and combustion products to the atmosphere?

The term "draft" refers to the pressure difference that facilitates the movement of air and combustion products from within a system to the outside atmosphere. This pressure difference is crucial for the proper operation of ventilation systems, ensuring that exhaust gases are effectively expelled and fresh air is drawn in. Draft is essential for combustion processes, as it helps maintain the necessary airflow for safe and efficient operation.

In the context of mechanical code, understanding draft is important for designing systems that safely manage combustion gases and ensure adequate ventilation in living and working spaces. The concept of draft encompasses various types, including both induced and natural drafts, each of which operates under different principles.

While other terms like "induced draft" and "natural draft" are specific types of drafts utilized in particular applications, they fall under the broader category of draft. The Venturi effect, while related to fluid dynamics and pressure differences, specifically describes a phenomenon where fluid speed increases as it passes through a constricted section of a pipe, which isn't directly about the movement of air and combustion products to the atmosphere in the same general sense as draft.

Thus, the understanding of draft is fundamental in mechanical systems to ensure they function safely and efficiently, aligning with the North Carolina Mechanical Code.