Fixed carbon dioxide extinguishing systems, for machinery spaces that are normally manned, are actuated by one control to open the stop valve in the line leading to the space, and __________.

Correct Answer: Option D — a separate control to release the CO2

To prevent accidental discharge in normally manned machinery spaces, 46 CFR requires a two-step actuation design comprising a control to open the line stop valve and a separate, distinct control to release the CO2 charge.