A gas cylinder is a pressure vessel used to store gases at above atmospheric pressure. High pressure gas cylinders are also called bottles. Although they are sometimes colloquially called "tanks", this is technically incorrect, as a tank is a vessel used to store liquids at ambient pressure and often has an open top.

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 or propane depending on the required heat output.

Materials

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 weldings for most gas cylinders, treated to be anti corrosive. There have been some newly developed lightweight gas cylinders from composite materials. Due to the very high tensile strength of carbon fibre, these vessels can be very light, but are much more difficult to manufacture.

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

Within the UK the "competent authority" — the DfT — implements the regulations and appointment of authorised cylinder testers is conducted by UKAS, who make recommendations to the VCA for approval of individual bodies.

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 — can be hydrostatically or ultrasonically tested and visually examined every few years. In the United States, hydrostatic/ultrasonic testing is required either every five years or every ten years, depending on cylinder and its service. Helium gas cylinders have the highest pressures possible when full, around 1000 atmospheres.

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, cylinders commonly have a protective collar or neck ring around the service valve assembly.

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. For gases that remain gaseous under ambient storage conditions, the upstream pressure gauge can be used to estimate how much gas is left in the cylinder according to pressure. For gases that are liquid under storage, e.g., propane, the outlet pressure is dependent on the vapor pressure of the gas, and does not fall until the cylinder is nearly exhausted. 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. Some fittings use a right-hand thread, while others use a left-hand thread; left-hand thread fittings are usually identifiable by notches cut into them.

In the United States, 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 United States, 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 United States.

Color coding

Gas cylinders are often color coded, but the codes are not standard across different jurisdictions, and sometimes are not regulated. Cylinder color can not safely be used for positive product identification; cylinders have labels to identify the gas they contain and the label alone should be used for positive identification.

Safety and standards

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. 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 burst discs are backed with a low-melting-point metal, so that the valve must be exposed to excessive heat before the burst disc can rupture.

The Compressed Gas Association sells a number of booklets and pamphlets on safe handling and use of bottled gases.

If a compressed gas cylinder tips over, causing the valve block to be sheared off, the rapid release of high pressure gas may cause the cylinder to be violently accelerated, potentially causing property damage, injury, or death. To prevent this, cylinders are normally secured to a fixed object or transport cart with a strap or chain.

Standards

ISO 11439: Gas cylinders — High pressure cylinders for the on-board storage of natural gas as a fuel for automotive vehicles ISO 15500-5: Road vehicles — Compressed natural gas (CNG) fuel system components — Part 5: Manual cylinder valve

Management

Carelessness with pressurized gas cylinders can have devastating consequences, including serious injuries or death, property and environmental damage.

Cylinders should be properly labeled and securely stored. Substances that may react with each other, e.g., oxidizers and flammable materials, should not be stored in close proximity.

Sizes

In scuba diving, the United States measures cylinder volume by the amount of free air that can be compressed into the cylinder; Europe measures the cylinder volume as the internal volume of the cylinder: e.g. United States 19 cubic feet = European 3 liter at 180 bar.

The below are example cylinder sizes and do not constitute an industry standard.

!Cyl. Size	! Size* Diameter X Height (inches) Includes 5.5 inches for valve and cap.	!Nominal* Tare Weight (lbs.) Includes 4.5 lbs. for valve and cap.	!Water Capacity (lbs.)	!Internal Volume @ 70°F (21°C), 1 ATM (liters/cubic feet)	!U.S. DOT Specs
K	9.25 X 60	135	110	49.9 / 1.76	3AA2400
A	9 X 51	115	96	43.8 / 1.55	3AA2015
B	8.5 X 31	60	37.9	17.2 / 0.61	3AA2015
C	6 X 24	27	15.2	6.88 / 0.24	3AA2015
D	4 X 18	12	4.9	2.24 / 0.08	3AA2015
AL	8 X 53	52	64.8	29.5 / 1.04	3AL2015
BL	7.25 X 39	33	34.6	15.7 / 0.55	3AL2216
CL	6.9 X 21	19	13	5.9 / 0.21	3AL2216
XL	14.5 X 50	75	238	108 / 3.83	4BA240
SSB	8 X 37	95	41.6	18.9 / 0.67	3A1800
10S	4 X 31	21	8.3	3.8 / 0.13	3A1800
LB	2 X 15	4	1	0.44 / 0.016	3E1800
XF	12 X 46	180		60.9 / 2.15	8AL
XG	15 X 56	149	278	126.3 / 4.46	4AA480
XM	10 X 49	90	120	54.3 / 1.92	3A480
XP	10 X 55	55	124	55.7 / 1.98	4BA300
QT	3 X 14 includes 4.5 inches for valve	2.5 includes 1.5 lbs for valve	2.0	0.900 / 0.0318	4B-240ET
LP5	12.25 X 18.25	18.5	47.7	21.68 / 0.76	4BW240
Medical E	4 x 26 excludes valve and cap	14 excludes valve and cap		4.5 / 0.16	3AA2015

See also

Bottled gas

Pressure vessel

Carbon fiber

Composite overwrapped pressure vessel

Filling Carousel

Industrial gas

Storage tank

UN Recommendations on the Transport of Dangerous Goods

References

Category:Pressure vessels Category:Anesthetic equipment Category:Gas technologies Category:Containers

ar:أسطوانة الأكسجين cs:Tlaková láhev de:Gasflasche es:Tanque de gas eo:Gasbotelego it:Bombola nl:Gascilinder ja:ボンベ pl:Butla gazowa pt:Botijão de gás

name	R.K.Laxman
birth date	October 23, 1924
birth place	Mysore, India
occupation	Cartoonist, Illustrator }}

Rasipuram Krishnaswamy Iyer Laxman (born October 23, 1924, Mysore, India) is an Indian cartoonist, illustrator, and humorist. He is widely regarded as India's greatest-ever cartoonist and is best known for his creation ''The Common Man''.

Birth and childhood

R. K. Laxman was born in Mysore. His father was a headmaster and Laxman was the youngest of six boys. One of his elder brothers, R.K. Narayan, went on to become one of India's best known English language novelists.

Laxman was engrossed by the illustrations in magazines such as ''Strand Magazine'', ''Punch'', ''Bystander'', ''Wide World'' and ''Tit-Bits'', even before he could read. Soon he was drawing on his own, on the floors, walls and doors of his house and doodling caricatures of his teachers at school; praised by a teacher for his drawing of a peepal leaf, he began to think of himself as an artist in the making. Another early influence on Laxman were the cartoons of the world-renowned British cartoonist, Sir David Low (whose signature he misread as "cow" for a long time) that appeared now and then in ''The Hindu''. Laxman notes in his autobiography, ''The Tunnel of Time'': }} Laxman was the captain of his local "Rough and Tough and Jolly" cricket team and his antics inspired the stories "Dodu the money maker" and "The Regal Cricket Club" written by his brother, Narayan. Laxman's idyllic childhood was shaken for a while when his father suffered a paralytic stroke and died around a year later, but the elders at home bore most of the increased responsibility, while Laxman continued with his schooling.

After high school, Laxman applied to the JJ School of Arts, Bombay hoping to concentrate on his lifelong interests of drawing and painting, but the dean of the school wrote to him that his drawings lacked, "the kind of talent to qualify for enrollment in our institution as a student", and refused admission. He finally graduated with a Bachelor of Arts from the University of Mysore. In the meantime he continued his freelance artistic activities and contributed cartoons to ''Swarajya'' and an animated film based on the mythological character, Narada.

Career

Beginning

Laxman's earliest work was for newspapers & magazines such as ''Swarajya'' and ''Blitz''. While still at the Maharaja's College of Mysore, he began to illustrate his elder brother R K Narayan's stories in ''The Hindu'', and he drew political cartoons for the local newspapers and for the ''Swatantra''. Laxman also drew cartoons, for the Kannada humour magazine, Koravanji. Incidentally, Koravanji was founded in 1942 by Dr M Shivaram who was a MBBS doctor and had a clinic around Majestic area in Bangalore. He started this monthly magazine, dedicating it to hilarious/satirical articles and cartoons. Dr Shivaram himself was an eminent humourist in Kannada. He encouraged Laxman quite a lot. He held a summer job at the Gemini Studios, Madras. His first full-time job was as a political cartoonist for the ''Free Press Journal''. Prominent Shiv Sena politician Bal Thackeray, was also an employee at the newspaper at that time. Laxman later joined ''The Times of India'', beginning a career that has spanned for over fifty years.

Other creations

Among his other works, Laxman is known for his distinctive illustrations in several books, most notably for the Malgudi stories written by his elder brother R.K. Narayan, which was later made as a serial directed by Shankar Nag. He also created a popular mascot for the Asian Paints group called ''Gattu''. Laxman has also penned a few novels. His cartoons have appeared in Hindi films such as ''Mr. and Mrs. 55'' and a Tamil Film "KAMARAJ".

R K Laxman Chair at Symbiosis International University

Symbiosis International University inaugurated a chair to honour R K Laxman, called the R K Laxman Chair, for research and studies in media and communication, to focus on thought leadership, guiding research and policy formation in media and communication.

Personal life

He was first married to Bharatanatyam dancer and movie actress Kamala Laxman (also known before marriage as Baby Kamala and Kumari Kamala). After a divorce, he married again and his second wife's (a children's book writer) name was also Kamala. He lives both in Mumbai and Pune. In a cartoon series named "The star I never met" in film magazine ''Filmfare'' he painted a cartoon of Kamala Laxman, with the title "The star I only met!".

In September 2003, Laxman was affected by a stroke which left him paralysed on his left side. He has partly recovered from its effects. On the evening of June 20, 2010, Laxman was admitted to Breach Candy Hospital in Mumbai after being transported by an air ambulance from Pune. His condition was said to be stable.

Awards

B.D. Goenka Award - The Indian Express

Durga Ratan Gold Medal - Hindustan Times

Padma Bhushan - Govt. of India

Padma Vibhushan - Govt. of India

Ramon Magsaysay Award for Journalism, Literature and Creative Communication Arts - 1984

Lifetime Achievement Award for Journalism - CNN IBN TV18, 29 January 2008.

Bibliography

The Eloquent Brush: A Selection of Cartoons from Nehru to Rajiv

50 Years of Independence through the eyes of R.K.Laxman

The Best of Laxman series

Hotel Riviera

The Messenger

Servants of India

''The Tunnel of Time'' (autobiography)

His autobiography ''Lakshmanrekha'' is published in Marathi.

The Reel World [cartoons]published by Marwah Studios

Brushing Up The Years- A Cartoonist's History of India- 1947 to the Present- Penguin Books

Multi-media

India Through The Eyes of R. K. Laxman - Then To Now (CD-ROM).

Laxman Rekhas-A TOI Publication

Quotation

When the American cartoonist Ranan Lurie asked him who the best Indian cartoonist was, Laxman flashed back, "I am." The second, third, fourth, fifth best man on the job? Laxman continued to repeat, "I am."

Notes

References

Laxman's-eye view Frontline Magazine - July 18–31, 1998

Category:Indian Hindus Category:Living people Category:1924 births Category:Indian cartoonists

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