Bottled gas

Bottled gas is a term used for substances which are gasous at Standard temperature and pressure(STP) and have been compressed and stored in steel or compositebottles known as gas cylinders.

Gas state in cylinder

There are three cases: the substance remains a gas at standard temperature but increased pressure, the substance liquifies at standard temperature but increased pressure, and the substance is liquified 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) so that the low temperature can be maintained by evaporative cooling.

Case I

Case I: the substance remains a gas at standard temperature but increased pressure:

1. acetyleneblack cylinder
2. airyellow cylinder
3. argonbrown cylinder
4. heliumbrown cylinder
5. oxygenblue cylinder (green in the US)

Case II

Case II: the substance liquifies at standard temperature but increased pressure:

1. butanesilver or gray cylinder
2. propanesilver cylinder (sometimes dark blue)

Case III

Case III: the substance is liquified at reduced temperature and increased pressure:

1. liquid helium
2. liquid nitrogen
3. liquid oxygen(LOX)

• note: cryogenicgases are typically equipped with some type of 'bleed' device to prevent overpressure from rupturing the bottle and to allow evaporative cooling 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 pressurewith some variation due to intermolecular forceand molecule size compared to an ideal gas. Normal high pressure gas cylinders or bottles will hold from 200 to 400 atmosphere (unit)s. The atmosphere units pressure held by the bottle is equivalent to the number of volumes of standard temperature and pressure of the gas held by the bottle for an ideal gas.

Special Handling Considerations

Because the contents are under high pressure and are sometimes hazardous, there are special safetyregulations 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.

Nomenclature Differences

USusage typically refers to bottled gas when discussing liquified petroleum gas. The usage of 'bottled gas' is sometimes used in medical supply also especially for portable oxygen tanks. Commonly, other industrial gases stored in cylinders are called 'gas cylinders' in the US. The UKand other parts of Europe more commonly refer to 'bottled gas' when discussing any usage whether industrial, medical or liquified petroleum.

Color coding

Different countries have different gas color codes. See the

• Virtual Anesthesia Machine - Color coding of gas piping and outlets
• British Compressed Gas Association ? Colour Coding of Cylinders
• Air Products ? European Gas Cylinder Identification Chart

External links

• Air Products
• Air Liquide
• Linde Gas

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Bottled+gas Wikipedia article Bottled gas.