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Cylinder Information

Cylinder Testing Cycles (UK) Click for printable version.

The UK testing cycle is dependant on the type of cylinder, and the type of valve that is fitted to it.

For surface use cylinders, i.e. ones that are fitted with a valve that cannot be used for diving purposes, and breathing apparatus cylinders, as used by the Fire Brigade etc, the test cycle is 5 years from DOM (Date of Manufacture). The first one being a visual test, and then a hydrostatic test every 5 years after that.

For scuba cylinders, if a regular scuba valve is fitted, then the test cycle reverts to a standard scuba test cycle, this being a visual after 2.5 years from DOM, then alternating between a hydro and a visual every 2.5 years from then on. The only exception to this is if the cylinder looks excessively well used or damaged externally. In this case the testing station can require the cylinder to be hydro tested again at the 2.5 year visual interval.

The cylinder hydrostatic test pressure is 1.5 times or 5/3 of the normal working pressure, so a 232BAR cylinder will be hydro tested to 348 - 386BAR, a 300 BAR cylinder being tested to 450 - 500BAR. This is a normal test pressure, and does not stress the cylinder or come close to a destructive test pressure.

Further Info

It is good practice to store the cylinders out of direct sunlight whenever possible, as the heating of the cylinder can lead to some seal failures under certain circumstances, but remember, our fire brigades do carry breathing cylinders on their backs into burning buildings, often getting a lot warmer than the boot of your car!

If a "For Surface Use Only" sticker is applied to a regular scuba tank fitted with a regular scuba valve, it has absolutely no bearing on the test cycle. It does not under any circumstances extend the testing cycle to 5 years. If it did, then every diver not wanting to have the statutory test would just stick a sticker on their cylinder.

Incidentally, if a cylinder is used for non breathing air requirements, and is not a standard scuba cylinder, i.e. a commercial gas cylinder, the test cycle can be extended as far as 10 years.