Written by Mario Medarevic
Whether you’re buying a used scuba tank, checking your current setup, or just curious about your gear, knowing how to decode the markings on a scuba cylinder is an important skill for every diver.
These markings tell you a lot: the tank’s specifications, service pressure, manufacturing date, and hydrostatic test history. While they may look like a string of random numbers and letters at first, once you understand what they mean, they’re actually quite straightforward.
Let’s break it down using a typical aluminum 80 cylinder as an example.
Understanding cylinder markings can help you:
Verify the age and condition of a used tank
Avoid purchasing a tank that’s overdue for hydrostatic testing
Understand pressure ratings and capacity for dive planning
Satisfy inspection requirements in both Canada and the U.S.
TC – Transport Canada: Indicates the tank meets Canadian specifications
3ALM – Canadian code for 3-gauge aluminum construction
207 – Service pressure in bars (207 bar = ~3000 psi)
This tells you the tank is certified for use in Canada and constructed from aluminum alloy with a working pressure of 207 bar.
DOT – U.S. Department of Transportation: Confirms compliance with U.S. specs
3AL – U.S. specification code for 3-gauge aluminum
3000 – Working pressure in pounds per square inch (psi)
This indicates the tank is also legal for use in the U.S. with a service pressure of 3000 psi.
This is the unique serial number assigned to the cylinder. It’s used for tracking the tank’s production and inspection records.
LUXFER – Manufacturer of the tank
10 – Month of manufacture (October)
A – Manufacturer’s inspection code
05 – Year of manufacture (2005)
SO80 – Model number indicating an 80 cubic foot tank at working pressure
This gives you the exact make, model, and manufacture date of the cylinder.
This set of markings shows the most recent hydrostatic test date.
In this example:
11 – Month of testing (November)
DO/69 12 – Registered facility and technician code
Tanks in Canada and the U.S. require hydrostatic testing every 5 years to remain in service.
Understanding your tank’s markings is about more than just curiosity—it’s about safety, compliance, and smart ownership. Whether you’re purchasing a used cylinder or simply doing a pre-dive check, being able to quickly decode a tank’s specs and history is an essential part of responsible diving.
If you’re unsure about any of the markings or need help evaluating a tank, visit us at Dive World. Our team can walk you through tank specs, hydro schedules, and what to watch for when shopping for cylinders.
📍 Visit our shop in Etobicoke
🌐 Learn more about tank inspections and servicing
📞 Call us for guidance on buying or maintaining your scuba cylinders
Dive safe. Dive informed. Dive World.
Questions? Call us at 416-503-3483 and speak to an experienced professional.