What indicates a thermal discharge in a gaseous oxygen system?

A ruptured blowout disc in a gaseous oxygen system is a clear indicator of a thermal discharge. This component is designed to fail under specific pressure conditions to relieve excess pressure that could lead to dangerous situations, such as a rupture of the system due to thermal expansion or other hazards. In the event of overheating or extreme pressure caused by thermal discharge, the blowout disc will rupture to prevent catastrophic failure, indicating that the system has exceeded safe operational limits.

The other options do not directly indicate a thermal discharge. Increased pressure readings could signify normal operational conditions or other issues, but they alone do not confirm a thermal discharge. Unusual noise from the system might suggest various problems, but it is not a definitive sign of thermal discharge. Cooler than normal output could indicate other issues with the system rather than a thermal discharge, as this condition does not typically occur due to thermal events associated with gaseous oxygen. Thus, the rupture of the blowout disc specifically signals that a thermal discharge has taken place, making it the most relevant indicator.