What does the term 'air-bound' refer to in the context of steam traps?

The term 'air-bound' in the context of steam traps refers to a situation where a trap cannot effectively discharge condensate because it is filled with air instead of steam or condensate. This condition occurs when air gets trapped within the system and prevents the proper flow of condensate, leading to inefficiencies in the steam system.

In steam systems, it's essential to ensure that steam is the dominant phase in the trap, as steam traps are designed to remove condensate while preventing steam loss. When air is trapped, it creates a barrier that inhibits the discharge of condensate, which can lead to water hammer, inadequate heating, and other operational problems.

Understanding this concept is critical for steamfitter professionals, as it helps in diagnosing issues related to steam traps and maintaining efficient system operation. The other choices describe different issues related to steam traps but do not accurately capture the specific problem of an air-bound condition.