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Bottled gas is a term used for substances which are gaseous at
standard temperature and pressure Standard may refer to: Flags * Colours, standards and guidons * Standard (flag), a type of flag used for personal identification Norm, convention or requirement * Standard (metrology), an object that bears a defined relationship to a unit of m ...
(STP) and have been compressed and stored in
carbon steel Carbon steel is a steel with carbon content from about 0.05 up to 3.8 per cent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, cobalt ...
,
stainless steel Stainless steel is a group of iron-based alloys that contain a minimum of approximately 11% chromium, a composition that prevents the iron from rusting and also provides heat-resistant properties. Different types of stainless steel include the e ...
,
aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a ...
, or
composite
composite
bottles known as
gas cylinder A gas cylinder is a pressure vessel for storage and containment of gases at above atmospheric pressure. High-pressure gas cylinders are also called ''bottles''. Inside the cylinder the stored contents may be in a state of compressed gas, vapor o ...

gas cylinder
s.


Gas state in cylinders

There are four cases: either the substance remains a gas at standard temperature but increased pressure, the substance liquefies at standard temperature but increased pressure, the substance is dissolved in a
solvent A solvent (from the Latin ''solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar mo ...
, or the substance is liquefied at reduced temperature and increased pressure. In the last case the bottle is constructed with an inner and outer shell separated by a vacuum (
dewar flask A vacuum flask (also known as a Dewar flask, Dewar bottle or thermos) is an insulating storage vessel that greatly lengthens the time over which its contents remain hotter or cooler than the flask's surroundings. Invented by Sir James Dewar ...
) so that the low temperature can be maintained by
evaporative cooling An evaporative cooler (also evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning systems, whic ...
.


Case I

The substance remains a ''gas'' at ''standard temperature'' and ''increased pressure'', its
critical temperature Critical or Critically may refer to: *Critical, or critical but stable, medical states **Critical, or intensive care medicine *Critical juncture, a discontinuous change studied in the social sciences. *Critical Software, a company specializing in mi ...
being below standard temperature. Examples include: * air *
argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppmv). It is more than t ...
*
fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative element, it is extremely reactive, as it re ...
*
helium Helium (from el, ἥλιος, Helios, lit=Sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boilin ...
*
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. With a standard atomic weight of , hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the universe, constitut ...

hydrogen
*
krypton Krypton (from grc, κρυπτός, translit=kryptos 'the hidden one') is a chemical element with the symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is ...
*
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about t ...
*
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well a ...


Case II

The substance '' liquefies'' at ''standard temperature'' but ''increased pressure''. Examples include: *
ammonia Ammonia is a compound of nitrogen and hydrogen with the formula NH3. A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct characteristic of a pungent smell. It is a common nitrogenous waste, p ...
*
butane Butane () or ''n''-butane is an alkane with the formula C4H10. Butane is a gas at room temperature and atmospheric pressure. Butane is a highly flammable, colorless, easily liquefied gas that quickly vaporizes at room temperature. The name butane ...
*
carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules consist of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmospher ...

carbon dioxide
(also packaged as a cryogenic gas, Case IV) *
chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a y ...
*
nitrous oxide Nitrous oxide, commonly known as laughing gas or nitrous, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, with a slight metallic scent and taste. At elevated temperatu ...
*
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a ...
*
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the smell of burnt matches. It is released naturally by volcanic acti ...


Case III

The substance is ''dissolved'' at ''standard temperature'' in a solvent. Examples include: * carbon dioxide in the form of a
soft drink A soft drink (see § Terminology for other names) is a drink that usually contains carbonated water (although some vitamin waters and lemonades are not carbonated), a sweetener, and a natural and/or artificial flavoring. The sweetener may be a ...
*
sulfur trioxide Sulfur trioxide (alternative spelling sulphur trioxide) is the chemical compound with the formula SO3. It has been described as "unquestionably the most important economically" sulfur oxide. It is prepared on an industrial scale as a precursor to s ...
in the form of
fuming sulfuric acid Oleum (Latin ''oleum'', meaning oil), or fuming sulfuric acid, is a term referring to solutions of various compositions of sulfur trioxide in sulfuric acid, or sometimes more specifically to disulfuric acid (also known as pyrosulfuric acid). Oleum ...
*
nitrogen dioxide Nitrogen dioxide is a chemical compound with the formula .It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year for use primarily in the production ...
in the form of
red fuming nitric acid Red fuming nitric acid (RFNA) is a storable oxidizer used as a rocket propellant. It consists of 84% nitric acid (), 13% dinitrogen tetroxide and 1–2% water. The color of red fuming nitric acid is due to the dinitrogen tetroxide, which breaks d ...
*
hydrogen chloride The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride gas ...
in the form of
muriatic acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the digestive ...
** Note: these four are most often found in containers other than metal bottles, and at low pressure, e.g. . *
acetylene Acetylene (systematic name: ethyne) is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas (lower hydrocarbons are generally gaseous in nature) is widely used as a fuel and a chemical buil ...
** Note: Acetylene cylinders contain an inert packing material, which may be agamassan, and are filled with a solvent such as
acetone Acetone, or propanone, is an organic compound with the formula (CH3)2CO. It is the simplest and smallest ketone. It is a colourless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscible with water and se ...
or
dimethylformamide Dimethylformamide is an organic compound with the formula (CH3)2NC(O)H. Commonly abbreviated as DMF (although this initialism is sometimes used for dimethylfuran, or dimethyl fumarate), this colourless liquid is miscible with water and the majority ...
. The acetylene is pumped into the cylinder and it dissolves in the solvent. When the cylinder is opened the acetylene comes back out of solution, much like a carbonated beverage bubbles when opened. This is a workaround to acetylene's propensity to explode when pressurized above 200 kPa or liquified.


Case IV

The substance is ''liquefied'' at ''reduced temperature'' and ''increased pressure''. These are also referred to as
cryogenic A medium-sized dewar is being filled with liquid nitrogen by a larger cryogenic storage tank. In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th IIR International Congress of Refrigeration (h ...
gases. Examples include: *
liquid nitrogen Students preparing homemade ice cream with liquid nitrogen. Liquid nitrogen—LN2—is nitrogen in a liquid state at low temperature ( boiling point at sea level). It is produced industrially by fractional distillation of liquid air. It is a col ...
(LN2) *
liquid hydrogen Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point of 33 K. However, for it to be in a fully liquid ...
(LH2) *
liquid oxygen Liquid oxygen—abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries—is the liquid form of molecular oxygen. It was used as the oxidizer in the first liquid-fueled rocket invented in 1926 by Robert H. Goddard, an applica ...
(LOX) *
carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules consist of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmospher ...

carbon dioxide
(also packaged as a liquefied gas, Case II) :Note: cryogenic gases are typically equipped with some type of 'bleed' device to prevent overpressure from rupturing the bottle and to allow
evaporative cooling An evaporative cooler (also evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning systems, whic ...
to continue.


Expansion and volume

The general rule is that one unit volume of liquid will expand to approximately 800 unit volumes of gas at
Standard temperature and pressure Standard may refer to: Flags * Colours, standards and guidons * Standard (flag), a type of flag used for personal identification Norm, convention or requirement * Standard (metrology), an object that bears a defined relationship to a unit of m ...
with some variation due to
intermolecular force Intermolecular forces (IMF) (or secondary forces) are the forces which mediate interaction between molecules, including forces of attraction or repulsion which act between atoms and other types of neighboring particles, e.g. atoms or ions. Intermole ...
and molecule size compared to an
ideal gas An ideal gas is a theoretical gas composed of many randomly moving point particles that are not subject to interparticle interactions. The ideal gas concept is useful because it obeys the ideal gas law, a simplified equation of state, and is amena ...
. Normal high pressure gas cylinders will hold gas at pressures from . An ideal gas pressurised to 200 bar in a cylinder would contain 200 times as much as the volume of the cylinder at atmospheric pressure, but real gases will contain less than that by a few percent. At higher pressures, the shortfall is greater.


Special handling considerations

Because the contents are under high pressure and are sometimes hazardous, there are special
safety Safety is the state of being "safe", the condition of being protected from harm or other non-desirable outcomes. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk. Meanings There are tw ...
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. In the
United States The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major self-governing territories, 326 India ...
, the
Compressed Gas Association The Compressed Gas Association (CGA) is an American trade association for the industrial and medical gas supply industries. The CGA publishes standards and practices that codify industry practices. In cases where government regulation is inspecif ...
(CGA) 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.) The European Industrial Gases Association and the British Compressed Gases Association provide similar facilities in Europe and the United Kingdom.


Nomenclature differences

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 using by one of several Trade names, or specifically as
butane Butane () or ''n''-butane is an alkane with the formula C4H10. Butane is a gas at room temperature and atmospheric pressure. Butane is a highly flammable, colorless, easily liquefied gas that quickly vaporizes at room temperature. The name butane ...
or
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a ...
depending on the required heat output.


Colour coding

Different countries have different gas colour codes but attempts are being made to standardise the colours of cylinder shoulders: * Colours of cylinders for Medical gases are covered by an International Organization for Standardization (ISO) standard, ISO 32; but not all countries use this standard. * Within Europe gas cylinders colours are being standardised according to EN 1089-3, the standard colours applying to the cylinder shoulder only; i.e., the top of the cylinder close to the pillar valve. * In the United States, colour-coding is not regulated by law. The user should not rely on the colour of a cylinder to indicate what it contains. The label or decal should always be checked for product identification.


European cylinder colours

The colours below are specific shades, defined in the European Standard in terms of RAL (color space system), RAL coordinates. The requirements are based on a combination of a few named gases, otherwise on the primary hazard associated with the gas contents:


Specific gases


Based on gas properties


Gas mixtures, mostly for diving

Diving cylinders are left unpainted (for aluminium), or painted to prevent corrosion (for steel), often in bright colors, most often fluorescent yellow, to increase visibility. This should not be confused with industrial gases, where a yellow shoulder means chlorine.


See also

* * *


References


Notes


Standards

* International Organization for Standardization, ISO 32: ''Gas cylinders for medical use—Marking for identification of content''. * European Committee for Standardization, CEN EN 1089-3: ''Transportable gas cylinders, Part 3 - Colour Coding''.


External links


Virtual Anesthesia Machine - 6 different color codes for medical gas cylinders, hoses and outlets

British Compressed Gases Association – Colour Coding of Cylinders

Air Products – European Gas Cylinder Identification Chart

Compressed Gas Association
(U.S.)
Gases and Welding Distributors Association
(U.S.)
European Industrial Gases Association
(E.U.)
British Compressed Gases Association
(UK) {{DEFAULTSORT:Bottled Gas Anesthesia Gases Welding Breathing gases Pressure vessels Gas technologies Industrial gases Fuel containers de:Gasflasche