Scuba Tank Markings
How to read the markings on a Scuba Tank in North America.
These markings are used in North America. The rest of the world has their own particular markings. Be aware that tanks purchased in one country may not be allowed to be filled in another country.
Explanation of the marks in the top line.
These are used in Canada but you might also find them on some U.S. tanks as well as the U.S. markings
"TC" or CTC (an older mark) Transport Canada
"3AL" Aluminum specification (Canada)
"M124" Service pressure (bar)
"T11.3KG" Tare weight (Kilograms)
Explanation of the marks in the middle line. (United States)
"DOT" United States Department of Transportation
"3AL" Aluminum specification (USA)
"1800" Service pressure (PSI)
"U372530" Serial number
"LUXFER" or M#### Manufacturing plant or distributor identification
Other manufacturers names you might see here are Catalina, Faber or P or PST ( for Pressed Steel)
You might also see the name of a scuba company such as Scubapro or USD.
If they order a large quantity of tanks they may choose to have their name used instead of the manufacturer.
Explanation of the marks in the bottom line.
"01" Month of manufacture
"A" Mark of independent inspector
"98" Year of manufacture
If it is a steel tank and there is a + stamped after the year it means that the tank may be filled to a pressure 10% higher than the pressure shown on the tank.
Aluminum tanks never have this designation.
Every 5 years, all tanks have to be hydro tested again.
You will find a new date stamped for each test.
Always look to the latest date for the + mark to see if the tank may still be filled to the 10% overfill. If the + is not there, the tank may only be filled to the pressure stamped on the tank.
"20#C02" C02 capacity
"TW24.9" Tare weight (LBS)
Some notes on other markings you may find on tanks.
There has been a common controversy over the original date on the scuba tank.
One group says it is the date of manufacture and the other group insists it is the date of the first hydrostatic test of the tank.
The truth is that it is both. Federal law requires that every high pressure tank be given a hydro test when it is made and before it can be sold.
You may find other markings that are optional.
For example, the test pressure of a tank might be shown as "TP4500", meaning that the test pressure is 4500 psi. It is 1.5 times the working pressure.”

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