Which of the following systems are not required to be classified as a high probability system?

The classification of a system in terms of high probability relates to how the system interacts with the environment and the potential risks it poses. An indirect open spray system does not typically require classification as a high probability system because it is designed to minimize direct exposure or potentially harmful effects.

Indirect open spray systems often operate using a design that reduces the likelihood of contaminants being aerosolized or released into the surrounding area. This aspect makes it less critical to classify it under high probability standards, especially compared to systems like direct expansion or chilled water systems, which have more direct environmental interactions.

In other words, the nature of an indirect open spray system, as it relates to its operational design and potential risks, allows it to be excluded from classification as a high probability system. This understanding is key for anyone working with various mechanical systems and their implications for safety and regulation compliance.