Non-Refillable Cylinder Gas Packaging Marks – what phrase must be included?

• A. The words "DO NOT REFILL" must be included, and the letters must be at least 5 mm in height
• B. The words "DO NOT REFILL" must be included, height not specified
• C. The phrase must be in red ink
• D. There is no requirement

Answer: (A)

The essential idea is safety labeling for non-refillable gas cylinders: there must be a clear prohibition against refilling that is easy to read. The wording DO NOT REFILL is required, and the letters must be at least 5 mm high so the message stays legible during handling and inspection. This combination ensures that anyone who encounters the cylinder quickly understands it cannot be refilled, reducing the risk of over-pressurization, contamination, or other hazards. The marking does not require red ink, and the standard does specify a minimum height, so options that omit either the phrase or the size aren’t compliant.