7440-59-7

colourless gas

Helium is a colorless, odorless, and tasteless gas. It is nonflammable.

Gases, diluent.

A colorless, odorless, noncombustible gas. Can asphyxiate. Inhalation causes the voice to become squeaky (Mickey Mouse voice). Exposure of the container to prolonged heat or fire can cause HELIUM(7440-59-7) to rupture violently and rocket. If liquefied, contact of the very cold liquid with water causes violent boiling. Pressures may build to dangerous levels if the liquid contacts water in a closed container. Used in arc welding, to trace leaks in refrigeration and other closed systems and as a lifting gas for lighter-than-air aircraft.

Chemically inert. These substances undergo no chemical reactions under any known circumstances. They are nonflammable, noncombustible and nontoxic. They can asphyxiate.

Vapors may cause dizziness or asphyxiation without warning. Vapors from liquefied gas are initially heavier than air and spread along ground.

It is used in weather balloons and in welding gases. Liquid helium is used as a closed system cooling agent.

Non-flammable gases. Containers may explode when heated. Ruptured cylinders may rocket.

If frostbite has occurred, seek medical attention immediately; do not rub the affected areas or flush them with water. In order to prevent further tissue damage, do not attempt to remove frozen clothing from frostbitten areas. If frostbite has NOT occurred, immediately and thor oughly wash contaminated skin with soap and water. Seek medical attention promptly. Breathing: Remove the person from exposure. Begin (using universal precautions, includ ing resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility.

UN1046 Helium, compressed, Hazard Class: 2.2; Labels: 2.2-Nonflammable compressed gas; UN1963 Helium, refrigerated liquid (cryogenic liquid), Hazard Class: 2.2; Labels: 2.2-Nonflammable compressed gas.

Helium is a colorless, odorless, and tasteless monoatomic gas with an atomic weight of 4, a density of 1.78 g per 1 at 0°C and 1 atmosphere pressure, and an aqueous solubility of 0.97 mL per 100 mL at 50°C. The Bunsen solubility coefficient (the volume, in mL, of gas at standard conditions dissolved per mL of liquid).
of helium at 38°C is 0.0086 in water, and 0.015 in olive oil. After hydrogen, helium is the most abundant element in the universe; these elements are believed to represent 76 and 23 percent, respectively, of all matter in the universe. The earth’s atmosphere, however, contains only 5 ppm of helium. Mineral gases from wells contain higher concentrations and serve as the principal source for industrial production. Helium is chemically very inert; it has a weak tendency to combine with other elements such as fluorine. It is usually marketed as compressed gas, with the USP grade containing not less than 99 percent helium.
The largest biological use of helium is the replacement for nitrogen in synthetic breathing gas mixtures for divers and others working under high pressure conditions. The low solubility in body fluids compared to nitrogen decreases the danger of bends on depressurizing.

Return refillable compressed gas cylinders to supplier.

Helium is a colorless, odorless, and tasteless inert gas that is noncombustible and is the leastsoluble of any gas in water and alcohol. As a gas, it diffuses well in solids. Helium’s freezingpoint is –272.2°C, and its boiling point is –268.93°C. Both temperatures are near absolutezero (–273.13°C, or –459.4°F), where all molecular and thermal motion ceases. Liquid heliumhas the lowest temperature of any known substance. Helium’s density is 0.0001785g/cm³.
Helium is the only element that cannot be converted into a solid by lowering the temperature.At normal pressure it remains a liquid at near absolute zero, but if the pressure isincreased, it then turns into a solid.

There are eight isotopes of helium. Two of these are stable. They are He-3,which makes up just 0.000137% of natural helium found on Earth, and He-4, whichaccounts for 99.999863% of the natural abundance of helium on Earth. Another isotope,He-5, is an extremely rare radioisotope that decays by emitting beta particles toform lithium-6 and lithium-8.

From the Greek word helios, meaning the “sun.” Through the process of spectrometry, it was discovered on the sun before it was found on Earth in 1868.

Helium is the 73rd most abundant element on Earth, but it is the second most abundant element in the universe, after hydrogen. Together, helium and hydrogen make up 99.9% of all the elements in the universe, but helium makes up only a small trace of the elements on Earth.
Most likely, helium was the first element to be formed after hydrogen during the Big Bang formation of the universe. The theory is that hydrogen atoms combined under great heat and pressure to form helium atoms. The Earth s current helium originally came from the natural decay of radioactive elements deep in the Earth. Much of it seeps up to the surface and escapes into the atmosphere, or it mixes with natural gas deposits deep in the Earth. Like hydrogen, it is a very light gas that escapes through cracks in the Earth s crust and sooner or later escapes from Earth s gravity into the atmosphere.
Helium can be obtained from the atmosphere by lowering the temperature of air until it liquefies. All the other gases in air will turn to a liquid except helium, because it has the lowest boiling point. Since helium, at this stage of cooling, will be the only vapor left, it can be removed as a pure gas. It is commercially more profitable to produce helium by separating it from a mix of natural underground gases, where its concentration is greater that in the atmosphere. Raw natural gas is a mixture of methane, nitrogen, and helium, with traces of other gases. The nitrogen and helium are separated from the methane, which is used as a fuel. This separation is accomplished by fractional distillation wherein the temperature is reduced and the gases are liquefied. As the temperature is reduced, methane is liquefied first, then nitrogen, leaving helium to be collected and sold commercially. Helium is then purified to 99.995%. Most of the world s supply of helium comes from the United States.

When a second proton and two neutrons are added to a hydrogen nucleus, a helium atomcan form after it collects two electrons. Helium is the most inert of all the noble group 18gases. It is so inactive that it does not even combine with itself. As a gas, helium remains asa single atom. The nuclei of helium are called alpha particles, each of which has a charge of+2 and an atomic mass of 4.
No stable compound of helium has ever been found. However, it is possible for an atom ofhydrogen to combine with helium (and other light noble elements) under special conditionsto form HeH+, an unstable ion.
Helium is not plentiful on Earth and is only the sixth most abundant gas in the atmosphere.It does not accumulate in the atmosphere because it is lighter than air. Some amountof helium continually escapes into space from the outer atmosphere of the Earth.
Liquid helium exhibits some unusual characteristics when supercooled. First, it is the onlyelement that will not turn into a solid by just using pressure. Heat must be removed as thepressure is increased, but helium will freeze at –272.2°C, which is the lowest temperature scientistshave ever achieved. Second, it is an excellent conductor of heat. As a supercold liquid,it will move toward heat—even flow up the sides and over the top of a container.

Helium is produced mostly by extraction from natural gas. The process involves cooling the stream of natural gas at sufficient low temperatures and high pressures to liquefy and separate all hydrocarbons, nitrogen and other gases from gaseous helium. The ‘crude’ helium gas may be purified further by repeated liquefaction of methane, nitrogen and other impurities under pressure. Trace hydrocarbons may be removed by adsorption on activated charcoal at liquid nitrogen temperature. Water may be removed by drying over a dehydrating agent such as bauxite. Carbon dioxide may be removed by passing helium through a scrubbing solution containing monoethanolamine-ethylene glycol or similar substances. Trace hydrogen may be removed from helium by converting it into water by mixing with oxygen and passing the mix over a palladium catalyst. Final purification may be achieved by adsorbing remaining trace contaminants over activated charcoal at liquid nitrogen temperature.
Alternatively, helium may be separated from natural gas by diffusion through permeable barriers, such as high silica glass or semipermeable membranes. The gas is supplied commercially in steel cylinders or tanks. The United States is the largest producer of helium in the world.

Dry the gas by passing it through a column of Linde 5A molecular sieves and CaSO4, then through an activated-charcoal trap cooled in liquid N2, to adsorb N2, argon, xenon and krypton. Also pass it over CuO pellets at 300o to remove hydrogen and hydrocarbons, over Ca chips at 600o to remove oxygen, and then over titanium chips at 700o to remove N2 [Arnold & Smith J Chem Soc, Faraday Trans 2 77 861 1981]. Its solubility in 100mL of H2O is 0.94mL at 25o, 1.05mL at 50o and 1.21 at 75o.

Being inert, the noble gases are nontoxic. However, they can act as asphyxiant gases thatcan kill because of oxygen deprivations.
A possible hazard is when He++ nuclei, as alpha particles, are accelerated to high speeds andbombard a target. Alpha particles can be stopped by several inches of air or a piece of cardboard.As high-energy, charged particles generated from man-made or natural radioactivity,alpha particles can cause damage, but they are not as damaging to our bodies as are very shortwavelength gamma rays, which can only be stopped by lead shielding.

Helium is a colorless, odorless, elementary gas,He, with a specific gravity of 0.1368, liquefyingat –268.9°C, freezing at –272.2°C. It has avalency of zero and forms no electron-bondedcompounds. It has the highest ionization potentialof any element. The lifting power of heliumis only 92% that of hydrogen, but it is preferredfor balloons because it is inert and nonflammable,and is used in weather balloons. It is alsoused instead of air to inflate large tires for aircraftto save weight. Because of its low density,it is also used for diluting oxygen in the treatmentof respiratory diseases. Its heat conductivityis about six times that of air, and it is usedas a shielding gas in welding, and in vacuumtube and electric lamps. Because of its inertnesshelium can also be used to hold free chemicalradicals, which, when released, give highenergy and thrust for missile propulsion. Whenan electric current is passed through helium itgives a pinkish-violet light, and is thus used inadvertising signs. Helium can be obtained fromatmospheric nitrogen, but comes chiefly fromnatural gas.

Gaseous helium is noncorrosive and inert, and may consequently be contained in systems constructed of any common metals and designed to safely withstand the pressures involved. At the temperature of liquid helium, ordinary carbon steels and most alloy steels lose their ductility and are considered unsafe for liquid helium service. Satisfactory materials for use with liquid helium include Type 18-8 stainless steel and other austenitic nickel-chromium alloys, copper, Monel, brass, and aluminum.

Helium is nontoxic and inert. It can act as a simple asphyxiant by diluting the concentration of oxygen in air below levels necessary to support life. Inhalation in excessive concentrations can result in dizziness, nausea, vomiting, loss of consciousness, and death. Death may result from errors in judgment, confusion, or loss of consciousness, which prevent self-rescue. At low-oxygen concentrations, unconsciousness and death may occur in seconds without warning.

Gaseous helium is commonly stored in high pressure cylinders, hydril tubes, or tube trailers. Liquid helium is commonly stored at the consumer site in cryogenic liquid cylinders, portable customer stations, and specially designed insulated tanks. To minimize helium transfer losses, the shipping container for liquid helium is normally used for storage.

CGA G-9.1, Commodity Specification for Helium, presents the component maxima, in parts per million (v/v) unless otherwise shown, for specific grades of helium, also known as quality verification levels (QVLs) [I]. A blank indicates no maximum limiting characteristic. The absence of a value in a listed QVL does not mean to imply that the limiting characteristic is or is not present, but merely indicates that the test is not required for compliance with the specification.