A valve body that seals on the down stroke is categorized as?

A valve body that seals on the down stroke is categorized as direct acting. In the context of valves, "direct acting" means the sealing mechanism is engaged when the actuator moves the valve stem downward. This design allows for a straightforward mechanism where the force directly results in sealing the flow, providing reliable operation under pressure.

Direct acting valves are commonly used in applications where immediate response and dependable sealing performance are required. By contrast, other valve types, such as reverse acting, would have a sealing mechanism engaged during the upstroke, which operates differently and may be more suited to specific applications where lower pressure differentials are involved. Understanding these distinctions is crucial for selecting the appropriate valve type for various refrigeration and HVAC applications.