Which type of supply air sources is not allowed in outdoor enclosures?

The correct response highlights that instrument air sources are not permitted in outdoor enclosures largely due to safety and practical considerations. Instrument air is typically used for pneumatic control systems within a facility and must maintain a certain level of purity and moisture content, which can be compromised in an outdoor environment. Exposing these systems to outdoor elements such as temperature variations, humidity, and contaminants can lead to performance issues and operational failures.

Additionally, the other types of supply air sources, such as vacuum supply systems, oxygen supply systems, and liquid oxygen tanks, have well-defined regulations and safety protocols for outdoor installation. They are designed and constructed to withstand environmental conditions, making them suitable for outdoor use. In contrast, instrument air systems do not have the same resilience and could potentially lead to operational and safety hazards if placed outdoors. This distinction underlines the importance of adhering to proper installation standards for different types of gas delivery systems in the context of medical applications.