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Scuba Tank Markings – Everything You Need To Know About Them

Scuba Tank Markings - principal

We know you have noticed the scuba tank markings. You have told us and you have asked us what their meaning is. In this article, we are going to explain them to you. You will know how the tank pressure is indicated, when the last annual inspection was carried out, and when the next one will be, among many other things. Are you ready to discover the scuba tank markings mystery? Let’s get started!

Deciphering Scuba Tank Markings

Scuba Tank Markings to Identify the Government Approval

Government approval often has codes like.

DOT: Scuba tanks marketed in the United States must be homologated according to the regulations of the corresponding Department Of Transportation (DOT)

CTC: These are the initials of the Canadian Transportation Commission (CTC or TC), the government agency that approves bottles in Canada.

CE: These scuba tanks follow the requirements of the European Union and must be approved according to EN standards.

Scuba Tank Markings That Tell Us What Metal They Are Made Of

Next to the letters “DOT” we discover a set of numbers and letters that refer to the metal from which the scuba tank is made.

Carbon steel = 3A. The first tanks were made of this material. The problem is this material has poor corrosion resistance and there are few in use.

Chromium-moly steel = 3AA. If your tank is made of steel, this code will be stamped on it.

Aluminum tanks are more difficult to identify. They can be distinguished with the codes SP6498, E6498. These numbers identify the aluminum permits for tank fabrication. 3AL is the code used to recognize aluminum tanks manufactured in the USA since 1982 and 3ALM, the nomenclature used in Canada.

DO YOU HAVE ANY DOUBT? 

Scuba Tank Markings - 2
Scuba Tank Markings - 2

Scuba Tank Markings That Tell Us What Metal They Are Made Of

Next to the letters “DOT” we discover a set of numbers and letters that refer to the metal from which the scuba tank is made.

Carbon steel = 3A. The first tanks were made of this material. The problem is this material has poor corrosion resistance and there are few in use.

Chromium-moly steel = 3AA. If your tank is made of steel, this code will be stamped on it.

Aluminum tanks are more difficult to identify. They can be distinguished with the codes SP6498, E6498. These numbers identify the aluminum permits for tank fabrication. 3AL is the code used to recognize aluminum tanks manufactured in the USA since 1982 and 3ALM, the nomenclature used in Canada.

DO YOU HAVE ANY DOUBT? 

Scuba Tank Markings to Indicate Work Pressure

PSI is the unit of pressure measurement used in USA, while Canada and the European Union use BAR. If you want to know the difference, we have an article that explains ” What’s The Difference Between Psi And Bar?“, we recommend carefully reading.

Well, the Scuba Tank Markings that follow the identification of the metal are numbers. They indicate the working pressure of the tank. In other words, the maximum pressure that the tank can be filled to (3000 PSI or 207 BAR). This pressure must not be exceeded unless the + sign appears next to the number. If you see this, you are generally looking at a steel tank and it indicates that it can be filled up to 10% more.

Scuba Tank Markings - 3
Other Scuba Tank Markings

Every scuba tank carries a unique serial number that identifies it. In the photo, you see a part of one of them painted green.

The serial number is followed by the manufacturer’s name. The ones we show in the photograph were made by Luxfer, but there are others known as Kidde or PST.

The following scuba tank markings refer to the date the cylinder was tested. First, we see the month and then, the year. The symbol or letter in the middle is the inspection code to identify the hydrostatic tester. Each tester records it with the DOT for identification.

And that’s all. Another diving mystery solved. Just as today we have discovered the meaning of the markings on scuba tanks, we will be happy to answer other questions. What’s more, we invite you to do so. Please write us your suggestions and doubts. We will answer them in the following posts.

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