15. The carbon dioxide cylinders of a fixed fire extinguishing system may be located inside the protected space, if the quantity of CO2 required to protect that space is not more than which amount?

Cylinders of a fixed fire extinguishing system may be located within the protected space if the required CO2 quantity does not exceed 300 pounds; exceeding this limit necessitates external cylinder placement to ensure crew safety and system reliability, as stipulated by Coast Guard regulations.