gas cylinder

Information about gas cylinder

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Industrial compressed gas cylinders used for oxy-fuel welding and cutting of steel.


For mechanical devices used to impart a force from a pressurized liquid or gas, see pneumatic cylinder.


A Gas cylinder or tank is a pressure vessel used to store gases at high pressure.

Applications

Applications for gas cylinders include:
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Butane gas cylinder used for cooking

Regulations and Testing

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), 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 independent quality agent that will inspect the product for quality and safety.

There are a variety of tests that may be performed on various cylinders. Some of the most common types of tests are hydrostatic test, burst test, tensile strength, Charpy impact test and pressure cycling.

During the manufacturing process, vital information is usually stamped or permanently marked on the cylinder. This information usually includes the type of cylinder, the working or service pressure, the serial number, date of manufacture, the manufacture's registered code and sometimes the test pressure. Other information may also be stamped depending on the regulation requirements.

High pressure cylinders that are used multiple times--as most are--are hydrostatically or ultrasonically tested and visually examined every few years. In the U.S., hydrostatic/ultrasonic testing is required either every five years or every ten years, depending on cylinder and its service.

Valve Connections

When gases are supplied in gas cylinders, the cylinders have a stop angle valve at the end on top. Often, gas cylinders are somewhat long and narrow and may stand upright on a flattened bottom at one end with the valve at the top. During storage, transportation, and handling when the gas is not in use, a cap may be screwed over the protruding valve to protect it from damage or breaking off in case the cylinder were to fall over. Instead of a cap, some cylinders have some sort of protective frame around the stop valve.

When the gas in the cylinder is ready to be used, the cap is taken off and a pressure-regulating assembly is attached to the stop valve. This attachment typically has a pressure regulator with upstream (inlet) and downstream (outlet) pressure gauges and a further downstream needle valve and outlet connection. The upstream pressure gauge indicates how much gas is left in the cylinder according to pressure. The regulator could be adjusted to control the flow of gas out of the cylinder according to pressure shown by the downstream gauge. The outlet connection is attached to whatever needs the gas supply, such as a balloon for example.

The valves on industrial, medical and diving cylinders are usually of different size and type, as are the valves for different products, making it more difficult to mistakenly misuse a gas.

In the US, valve connections are sometimes referred to as 'CGA connections,' since the Compressed Gas Association (CGA) publishes guidelines on what connections to use for what products (e.g., In the USA, an argon cylinder will have a CGA 580 connection on the valve). High purity gases will sometimes use CGA-DISS ('Diameter Index Safety System') connections.

In the EU, DIN connections are more common than in the US.

Color Coding

Gas cylinders are often color coded, but the codes are not standard across different jurisdictions, and sometimes are not regulated. Cylinder color should not be used for positive product identification. Gas cylinders have labels affixed to them which identify the product they contain and the label alone should be used for positive identification. When the identification provided by the label is dubious, it should be marked Contents Unknown and returned to the manufacturer.

Safety

Because the contents are under pressure and are sometimes hazardous, there are special safety regulations for handling bottled gases. These include chaining bottles to prevent falling and breaking, proper ventilation to prevent injury or death in case of leaks and signage to indicate the potential hazards. Installing and replacing gas cylinders should be done by trained personnel.

In a fire, the pressure in a gas cylinder rises in direct proportion to its temperature (see the ideal gas law). If the internal pressure exceeds the mechanical limitations of the cylinder and there are no means to safely vent the pressurized gas to the atmosphere, the vessel will fail mechanically. If the vessel contents are ignitable, this event may result in a "fireball". If the cylinder's contents are liquid but become a gas at ambient conditions, this is commonly referred to as a Boiling Liquid Expanding Vapour Explosion (BLEVE).

Medical gas cylinders in the UK and other countries have a seal of Wood's metal between the valve block and the cylinder body. This seal melts at a comparatively low temperature (70°C) and allows the contents of the cylinder to escape in a controlled fashion, lessening the risk of explosion.

More common pressure relief devices are of a simple burst disc type. In these, a small burst disc is installed in the back of the valve. A burst disc is a small metal gasket engineered to rupture at a pre-determined pressure. Some of these burst disc are backed with a low-melting-point metal, so that the valve must be exposed to excessive heat before the burst disc can rupture.

If the valve of a compressed air cylinder is broken or sheared off, the released pressure will cause the cylinder to act like a rocket, shooting away quickly.

The Compressed Gas Association sells a number of booklets and pamphlets on safe handling and use of bottled gases. (Members of the CGA can get the pamphlets for free.)

See also

External links

The term air cylinder can also refer to a gas cylinder used to store compressed air, including those used for scuba diving.

Pneumatic cylinders (sometimes known as air cylinders
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A tank is an armoured combat vehicle.

Tank may also refer to:

Containers

  • Irrigation tank, in India, refers to an artificial lake or reservoir of any size. This is the original meaning.

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A pressure vessel is a closed, rigid container designed to hold gases or liquids at a pressure different from the ambient pressure. The end caps fitted to the cylindrical body are called heads.
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Gas is one of the four major states of matter, consisting of freely moving atoms or molecules without a definite shape. Compared to the solid and liquid states of matter a gas has lower density and a lower viscosity.
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Pressure (symbol: p) is the force per unit area applied on a surface in a direction perpendicular to that surface.

Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.
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Pneumatics is the use of pressurized air to effect mechanical motion. Pneumatics is employed in a variety of settings. In dentistry applications, pneumatic drills are lighter, faster, and simpler than an electric drill of the same power rating (because the prime mover, the compressor, is
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Transport or transportation is the movement of people and goods from one place to another. The term is derived from the Latin trans ("across") and portare ("to carry").
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Industry (from Latin industrius, "diligent, industrious"), is the segment of economy concerned with production of goods. Industry began in its present form during the 1800s, aided by technological advances, and it has continued to develop to this day.
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Medicine is the science and "" of maintaining and/or restoring human health through the study, diagnosis, and treatment of patients. The term is derived from the Latin ars medicina meaning the art of healing.
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Air is the most common and only natural breathing gas. Other artificial gases, either pure gases or mixtures of gases, are used in breathing equipment and enclosed habitats such as SCUBA equipment, surface supplied diving equipment, recompression chambers, submarines, space suits,
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diving cylinder, scuba tank or diving tank is used to store and transport high pressure breathing gas as a component of an Aqua-Lung. It provides gas to the SCUBA diver through the demand valve of a diving regulator.
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Fuel is any material that is burnt or altered in order to obtain energy.[1] Fuel releases its energy either through chemical means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion.
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The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber. This exothermic reaction creates gases at high temperature and pressure, which are permitted to expand.
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Heating may refer to:
  • HVAC: Heating, ventilation and air-conditioning
Heating devices, or systems:
  • Block heater, or headbolt heater, an electric heater that heats the engine of a car to ease starting in cold weather
  • Boiler

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Cooking is the act of preparing food for eating by the application of heat. It encompasses a vast range of methods, tools and combinations of ingredients to alter the flavor or digestibility of food.
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Liquefied petroleum gas (also called LPG, LP Gas, or autogas) is a mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles, and increasingly replacing chlorofluorocarbons as an aerosol propellant and a refrigerant to reduce damage to the
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Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. Butane is also used as a collective term for n
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Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. It is derived from other petroleum products during oil or natural gas processing. It is commonly used as a fuel for engines, barbecues, and home heating systems.
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Oxy-fuel welding (commonly called oxyacetylene welding or oxy welding or in the U.S. gas welding) and Oxy-fuel cutting are processes that use fuel gases and oxygen to either weld or cut metals.

There are a few differences between the two.
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United States Department of Transportation

Seal of the Department of Trasportation
Agency overview
Formed April 1, 1967

Jurisdiction United States of America
Headquarters Washington, D.C.
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Department Website Transport Canada is the department within the government of Canada which is responsible for developing regulations, policies and services of transportation in Canada.
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A hydrostatic test is the common way in which leaks can be found in pressure vessels such as pipelines and plumbing. This method of testing should not be confused with the Hydrostatic Body Fat Test that uses the principles of buoyancy to calculate a persons body fat.
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Tensile strength , or measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks.

Explanation


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The Charpy impact test is a standardized high strain-rate test which determines the amount of energy absorbed by a material during fracture. This absorbed energy is a measure of a given material's toughness and acts as a tool to study brittle-ductile transition.
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valve is a device that regulates the flow of substances (either gases, fluidized solids, slurries, or liquids) by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but usually are discussed separately.
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pressure gauges or vacuum gauges

A manometer is a pressure measuring instrument, usually limited to measuring pressures near to atmospheric. The term manometer is often used to refer specifically to liquid column hydrostatic instruments.
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A needle valve is a type of valve having a small orifice and a threaded, needle-like plunger. It allows precise regulation of flow, although it is generally used for, and is capable of, only relatively small flow rates.
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balloon is a flexible bag normally filled with a gas, such as helium, hydrogen, nitrous oxide or air. Early balloons were made of dried animal bladders. Modern balloons can be made from materials such as rubber, latex, polychloroprene or a nylon fabric.
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screw thread is a helical or tapered structure used to convert between rotational and linear movement or force.

Screw threads have several applications:
  • Fasteners such as wood screws, machine screws, nuts and bolts.

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Deutsches Institut für Normung e.V. (DIN; in English, the German Institute for Standardization) is the German national organization for standardization and is that country's ISO member body.
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