Which part of the central supply system provides support when the primary and secondary supplies are not functioning?

The correct answer highlights the role of the reserve supply within a central medical gas supply system. When both primary and secondary supplies are offline or compromised, the reserve supply is designed to engage automatically. This ensures that critical medical gases are still available for patient care, which is crucial in a healthcare setting where continuous availability of these gases can be a matter of life or death.

The concept behind the reserve supply is to maintain an additional layer of safety and reliability. It acts as a backup that can immediately kick in, allowing healthcare providers to continue treating patients without delay or interruption, even during unforeseen circumstances affecting the main supplies.

Other components of the system, such as the operating supply and local or master alarms, serve different purposes. Operating supply refers to the gases currently in use, while alarms serve to notify personnel of troubles or changes in gas pressure or flows, but they don’t provide the actual gas supply required in an emergency.