What are tube stubs used for in relation to drums and headers?

Tube stubs serve a crucial purpose in the design of refrigeration systems, particularly regarding drums and headers. They are constructed as short length tubes that extend from the main body of the drum or header, allowing for the proper attachment of other components without compromising the integrity of the system.

When used as nozzles, tube stubs enable the flow of refrigerants or other fluids into and out of the drum or header. This is essential for maintaining the flow dynamics within the system and ensuring efficient operation. Furthermore, tube stubs help facilitate the connection of various piping systems, allowing for effective routing of refrigerants throughout the refrigeration cycle.

In the context of the other options, flanges are typically used for bolted connections between two components; manifolds are used mainly to distribute flow to different paths but don't directly connect to a drum; and fittings are general connectors but not specifically designed for the unique attachment needs related to the function of tube stubs. Thus, the designation of tube stubs as nozzles underscores their primary function in facilitating fluid entry and exit in refrigeration systems.