Which color indicates nonflammable gas?

• A. Green
• B. Blue
• C. Yellow
• D. Red

Answer: (A)

Color coding on gas cylinders uses green to indicate nonflammable gas. This quick visual cue helps you identify the type of hazard at a glance, so you can choose the appropriate precautions—like avoiding ignition sources and ensuring proper ventilation—without delaying response. Remember, a green cylinder can still pose serious risks (such as asphyxiation or toxicity), so always verify the gas name on the cylinder and consult the label and Safety Data Sheet before handling. The other colors map to different hazards—red signals flammable gas, blue is commonly used for toxic gas, and yellow denotes oxidizers—each requiring specific precautions.