What type of alarm system must instrument air systems have to indicate when the backup compressor is in operation?

A local alarm system is essential for instrument air systems to indicate when the backup compressor is in operation because it provides immediate, localized notifications to personnel who are directly overseeing the equipment. This is critical in ensuring that operators are aware of any change in the system's status, especially when the primary compressor has failed or is out of service.

Local alarms allow for quick response times, which is vital in medical settings where the reliability of medical gas systems is paramount. By directly alerting those in close proximity to the equipment, local alarms help maintain safety and operational integrity by preventing unnoticed failures that could compromise patient care.

In contrast, remote alarms may notify personnel who are not on-site, which could delay necessary actions. Centralized alarms might provide a broader view of the system but still come with potential delays in response. The option suggesting that no alarm is required undermines the critical nature of instrument air systems, as not having an alarm could lead to dangerous situations when a backup compressor is activated without the knowledge of the operators. Thus, a local alarm system is vital for maintaining real-time awareness and responsiveness in the management of medical gas systems.