Which of the following is NOT a marking on a SCUBA cylinder?

• A. Color
• B. Manufacture Date
• C. Serial Number
• D. Regulatory Authority

Answer: (A)

Color is not an official marking you rely on for safety or certification. A scuba cylinder should have stamped markings that prove who made it, its unique serial number, the regulatory authority approving it, and the hydrostatic test date (including the due date for the next test) and service pressure. These markings verify the cylinder’s identity, legal compliance, and that it has been inspected within the required interval. Color coding, while sometimes used informally to identify gas or tank type, can be changed or misused and is not a dependable or standardized marking.