What color is the nitrogen cylinder?

• A. Black
• B. White
• C. Purple
• D. Teal

Answer: (A)

Gas cylinder color coding is a quick visual cue to identify contents in the hospital. Nitrogen is depicted as black in many standard healthcare color schemes, signaling an inert, nonflammable gas used as a diluent or to purge lines. This helps distinguish it from oxygen, which is typically green, and from other gases with their own distinct colors. Keep in mind that color codes can vary by country or supplier, so always read the cylinder label and verify the valve tag before use. The other color options don’t match the common nitrogen code, since white, purple, or teal aren’t the standard colors for nitrogen in typical medical practice.