Gaseous argon is tasteless, colorless, odorless, noncorrosive, and nonflammable. Argon belongs to the family of rare inert gases. It is the most plentiful of the rare gases making up approximately 1% of the earth’s atmosphere. It is monatomic and extremely inert, forming no known chemical compounds.
Since argon is inert, special materials of construction are not normally required. Vessels and piping must be selected and designed to withstand the pressure and temperatures involved and comply with applicable codes and regulations.
Manufacture Argon is produced by an air separation unit (ASU) through the liquefaction of atmospheric air and separation of the argon by continuous cryogenic distillation. The argon is then removed as a cryogenic liquid.
The metals and semiconductor manufacturing industries employ argon as a purge or inerting gas in furnaces, or other processing steps. In some instances, liquid argon is introduced and then vaporized over the surface of volatile or reactive molten metals to significantly reduce oxidation and/or volatility using an inert “blanket” of gas.
High-volume flow rates of argon are introduced via specialized lances or “tuyeres” in a variety of melting and refining processes. The argon typically acts as a “shroud” gas to provide protection to the tuyere. It also promotes removal of impurities and/or dissolved gases in several refining processes.
Argon is also widely used in the lighting industry for filling bulbs and in combination with other rare gases for special color effects. Health effects Table 1: Compressed Argon Physical and Chemical Properties Since argon is odorless, colorless, Chemical Formula Ar tasteless, and nonirritating, it has no Molecular Weight 39.95 warning properties. Argon is non- Boiling Point @ 1 atm –302.6°F (–185.9°C) toxic and inert. It can act as a simple Freezing Point @ 1 atm –308.8°F (–189.4°C) asphyxiant by displacing the oxygen Critical Temperature –188.4°F (–122.4°C) in air to levels below that required to Critical Pressure 705.8 psia (48.0 atm) support life. Inhalation of argon in ex- Density, Liquid, @ BP, 1 atm 87.02 lb/ft3 (1394 kg/m3) cessive amounts can cause dizziness, Density, Gas @ 68°F (20°C), 1 atm 0.1034 lb/ft3 (1.656 kg/m3) nausea, vomiting, loss of conscious- Specific Gravity, Gas (air=1) @ 68°F (20°C), 1 atm 1.38 ness, and death. Death may result Specific Gravity, Liquid (water=1) @ 68°F (20°C), 1 atm 1.40 from errors in judgment, confusion, or Specific Volume @ 68°F (20°C), 1 atm 9.68 ft3/lb (0.604 m3/kg) loss of consciousness, which prevents Latent Heat of Vaporization 69.8 Btu/lb (162.3 kJ/kg) self- rescue. At low oxygen concen- Expansion Ratio, Liquid to Gas, BP to 68°F (20°C) 1 to 840 trations, unconsciousness and death may occur in seconds and without warning. Cylinders Valve connections Personnel, including rescue workers, Cylinders are manufactured according Different valve outlet connections are should not enter areas where the to Transportation regulations, which used based on national or regional oxygen concentration is below 19.5%, specify the material of construction, standards. In North America, the unless provided with a self-contained method of manufacture, testing, and Compressed Gas Association (CGA) breathing apparatus (SCBA) or what products they are permitted to recommends three different connec- air-line respirator. be filled with, as well as other details. tions for argon, depending on the A cylinder is a hollow tube with a pressure of the container. In addi- For more information on oxygen- closed concave base that permits it tion, a high-integrity connection, also deficient atmospheres, consult to stand upright. The opposite end is known as a Diameter Index Safety Air Products’ Safetygram #17, “Dangers tapered to a small opening, threaded System (DISS) connection, has been of Oxygen-Deficient Atmospheres.” to accommodate the installation of assigned to argon. Cylinders contain- a valve. A threaded neck ring is at- ing argon at pressures up to 3,000 psig Containers tached to the tapered end to allow a use a CGA 580 connection; cylinders Argon is shipped and stored in high- protective cylinder cap to be installed. with pressures between 3,001 and pressure cylinders, tubes, or tube Cylinders may be used individually or 5,500 psig use the CGA 680 connec- trailers, depending upon the quantity in groups. When used in groups, the tion; and cylinders with pressures required by the user. Containers are cylinders should be piped together for between 5,501 and 7,500 psig use a designed and manufactured according stationary storage or to form portable CGA 677 connection. The DISS connec- to applicable codes and specifications banks. tion assigned to argon is 718. for the pressures and temperatures involved. The quantity of product a Tubes Pressure-relief devices container can hold is determined by Tubes are manufactured according to In North America and Asia, argon con- its water capacity and pressure rating. varying regional standards and regu- tainers are equipped with pressure- lations, depending on whether they relief devices to protect from overpres- are used for transportation or mount- surization. Argon cylinders less than ed permanently at a site. Tubes are 65" long use a frangible disk device. generally mounted on a truck-trailer Cylinders over 65" use a combination chassis or railcar bed or placed at sta- device consisting of a frangible disk tionary locations when large amounts backed by a fusible alloy. Combination of argon are needed. A tube is a pipe devices require that both the tempera- that is tapered on both ends. Each end ture and pressure requirements be is threaded to allow the installation of reached before the device will relieve. valves, connections, or relief devices. In Europe, pressure relief devices are not commonly used on cylinders. Shipment of gaseous Storage • If difficulty is experienced operat- • Cylinders should be stored up- ing the container valve or using the argon container connections, discontinue Compliance with applicable right in a well ventilated, dry, use and contact the gas supplier. Dangerous Goods regulations is cool, secure area that is protected Use only the proper connections required for all shipments by motor from the weather and preferably on the container. DO NOT USE freight, rail, air and water. These regu- fire-resistant. ADAPTERS! lations describe the marking, labeling, • No part of a cylinder should ever placarding, and shipping papers re- be allowed to exceed 125˚F (52˚C) • Always open a compressed gas quired. International shipments by air and areas should be free of combus- cylinder valve slowly to avoid rapid must comply with International Air tible materials. Never deliberately system pressurization. Transport Association/International overheat a cylinder to increase the • NEVER insert an object (e.g. wrench, Civil Air Organization (IATA/ICAO) pressure or discharge rate. Dangerous Goods regulations. Final screwdriver, pry bar, etc.) into the acceptance for air transport is at the • Cylinders should be stored away opening of the cylinder cap. Doing discretion of the airline. International from heavily traveled areas and so may damage or inadvertently shipments by water must com- emergency exits. open the valve. Use only a specially ply with International Maritime designed strap-wrench to remove Organization (IMO) regulations. • Avoid areas where salt and other overtightened or rusted caps. corrosive materials are present. • Never tamper with the safety de- Safety considerations • The valve outlet seal and valve pro- vices on valves or cylinders. The hazards associated with argon are tective cap should be left in place asphyxiation and the high pressure of until the cylinder has been secured • Use piping and equipment designed the gas in containers and systems. against a wall or bench, or placed in to withstand the maximum pres- sures encountered. If oxygen-deficient atmospheres are a cylinder stand and is ready for use. suspected or can occur, use oxygen • When returning empty cylinders, • Use a pressure reducing regulator monitoring equipment to test for insure the valve is closed and that or separate control valve along with oxygen-deficient atmospheres. some positive pressure remains properly designed pressure relief Review the appropriate Safety Data in the cylinder. Replace any valve devices to safely discharge gas to Sheet (SDS). outlet and protective caps originally working systems. shipped with the container, and • Use a check valve to prevent reverse Buildings label the cylinder as “Empty.” Do gas flow into the containers. Provide adequate ventilation in areas not store full and empty containers using argon. Provide monitoring for together. • It is recommended that all vents be areas where oxygen displacement piped to the exterior of the building may occur. A 19.5% oxygen concentra- Handling and are in accordance with local tion in the air is the minimum recom- • Never drop, drag, roll or slide cyl- regulations. mended for working without special inders. Use a specifically designed breathing equipment. hand-truck for cylinder movement. • Refilling or shipping a compressed gas cylinder without the consent of Remember, argon has no warning • Never attempt to lift a cylinder by the owner is not allowed. properties! its cap.
• Wrenches should never be used to open or close a valve equipped with a handwheel. If the valve is faulty, contact the gas supplier. Personal protective Emergency Response System T 800-523-9374 (Continental U.S. and Puerto Rico) equipment (PPE) T +1-610-481-7711 (other locations) Personnel must be thoroughly For regional ER telephone numbers, please refer to the local SDS 24 hours a day, 7 days a week for assistance involving Air Products and Chemicals, Inc. products familiar with properties and safety considerations before being allowed Technical Information Center to handle argon and/or its associated T 800-752-1597 (U.S.) equipment. Safety glasses, safety T +1-610-481-8565 (other locations) shoes, and leather work gloves are Monday–Friday, 8:00 a.m.–5:00 p.m. EST recommended to handle cylinders. In F 610-481-8690 [email protected] emergency situations, wear a self- contained breathing apparatus (SCBA). For more information, please contact us at: First aid Persons suffering from lack of oxygen Corporate Headquarters should be moved to fresh air. If the Air Products and Chemicals, Inc. victim is not breathing, administer 1940 Air Products Blvd. artificial respiration. If breathing is Allentown, PA 18106-5500 T: 610-481-4911 difficult, administer oxygen. Obtain immediate medical attention.
Self-contained breathing apparatus (SCBA) may be required to prevent asphyxiation of rescue personnel.
Fighting fires Since argon is nonflammable, special fire-fighting equipment and instruc- tions are not needed. However, upon exposure to intense heat or flame, a cylinder containing argon may vent rapidly and/or rupture violently. Most cylinders are designed to vent contents when exposed to elevated temperatures. Pressure in a cylinder or other container can build up due to heat, and it may rupture if the pressure-relief device fails to function.
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