A cylinder shall ________ if it is NOT suitable for continued service.

A cylinder that is deemed unsuitable for continued service must not be filled to prevent potential hazards. Filling an unsuitable cylinder poses significant risks such as leaks, ruptures, or other failures that could lead to dangerous situations, including explosions or fires. The integrity of a cylinder is paramount for safe use, and when a cylinder shows signs of damage, corrosion, age, or any other fault, it must be clearly marked as not suitable for filling or use. This ensures that safety protocols are strictly adhered to, protecting both individuals and property from potential propane-related incidents.

This principle underscores the importance of regular inspections and proper maintenance of propane cylinders to ensure they remain safe for use. When a cylinder is marked as unsuitable, it effectively communicates to users that it should be taken out of service, preventing any filling or unauthorized use until it is repaired or replaced.