Gas cylinders

A gas cylinder or tank is a pressure vessel used to store gases at above atmospheric pressure. High-pressure gas cylinders are also called bottles.

In the United States, "bottled gas" typically refers to liquefied petroleum gas. "Bottled gas" is sometimes used in medical supply, especially for portable oxygen tanks. Packaged industrial gases are frequently called "cylinder gas", though "bottled gas" is sometimes used.

The United Kingdom and other parts of Europe more commonly refer to "bottled gas" when discussing any usage whether industrial, medical or liquefied petroleum. However, in contrast, what the United States calls liquefied petroleum gas is known generically in the United Kingdom as "LPG"; and it may be ordered by using one of several trade names, or specifically as butane or propane depending on the required heat output.

The world's first natural gas cylinders were invented in China during the Tang dynasty where the Chinese drilled deep boreholes to retrieve natural gas and used bamboo tubes to collect and transport it.

For a detailed discussion about the materials for gas cylinders see pressure vessel.

Design codes and application standards along with the cost of materials dictated the choice of steel with no welds for most gas cylinders, treated to be anti corrosive. There have been some newly developed lightweight gas cylinders from stainless steel and composite materials. Due to the very high tensile strength of carbon fiber, these vessels can be very light, but are much more difficult to manufacture.

The transportation of high-pressure cylinders is regulated by many governments throughout the world. Various levels of testing are generally required by the governing authority for the country in which it is to be transported. In the United States, this authority is the United States Department of Transportation (DOT). Similarly in the UK, the European transport regulations (ADR) are implemented by the Department for Transport (DfT). For Canada, this authority is Transport Canada (TC). Cylinders may have additional requirements placed on design and or performance from independent testing agencies such as Underwriter's Laboratory (UL). Each manufacturer of high-pressure cylinders is required to have an independent quality agent that will inspect the product for quality and safety.

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