The carbon dioxide cylinders of all fixed fire extinguishing systems shall be retested and remarked whenever a cylinder remains in place on a vessel for __________. (small passenger vessel regulations)

Correct Answer: Option D — 12 years from the latest test date stamped on the cylinder

Under 46 CFR 181.400, fixed carbon dioxide fire extinguishing system cylinders must be retested and remarked every 12 years from the date of the last test stamped on the cylinder. This periodic hydrostatic testing ensures the pressure vessels remain capable of safely containing the extinguishing agent under emergency conditions.