Welding/Industrial Gases

Industrial

Mixes

LPG Gases

Acetylene (C2H2)

Acetylene (C2H2) is a colorless, highly flammable gas. Acetylene (systematic name: ethyne) is the simplest alkyne hydrocarbon, consisting of two hydrogen atoms and two carbon atoms connected by a triple bond. Because it contains a triple bond, acetylene is an unsaturated chemical compound. The carbon-carbon triple bond leaves the carbon atoms with two sp hybrid orbitals for sigma bonding, placing all four atoms in the same straight line, with CCH bond angles of 180°. Acetylene was discovered in 1836 by Edmund Davy who identified it as a "new carburet of hydrogen." It was rediscovered in 1860 by French chemist Marcellin Berthelot, who coined the name "acetylene." Molecular Weight = 26.04. Specific Gravity (Air =1) 0.908.

Applications

Approximately 80 percent of the acetylene produced annually in the United States is used in chemical synthesis. The remaining 20 percent is used primarily for oxyacetylene gas welding and cutting due to the high temperature of the flame; combustion of acetylene with oxygen produces a flame of over 3300 °C (6000 °F), releasing 11.8 kJ/g. Oxyacetylene is the hottest burning fuel gas. (Only the solid fuels can produce higher temperature chemical flame.) Acetylene is also used in the acetylene ('carbide') lamp, once used by miners (not to be confused with the Davy lamp), on vintage cars, and still sometimes used by cavers. In this context, the acetylene is generated by dripping water from the upper chamber of the lamp onto calcium carbide (CaC2) pellets in the base of the lamp. In former times a few towns used acetylene for lighting, including Tata in Hungary where it was installed on 24 July 1897, and North Petherton, England in 1898. In modern times acetylene is sometimes used for carburization (that is, hardening) of steel when the object is too large to fit into a furnace. Acetylene has been proposed as a carbon feedstock for molecular manufacturing using nanotechnology. Since it does not occur naturally, using acetylene could limit out-of-control self-replication. Acetylene is used to volatilize carbon in radiocarbon dating. The carbonaceous material in the archeological sample reacted in a small specialized research furnace with lithium metal to form lithium carbide (also known as lithium acetylide). The carbide can then be reacted with water, as usual, to form acetylene gas to be fed into mass spectrometer to sort out the isotopic ratio of carbon 14 to carbon 12.

Argon (Ar)

Argon (Ar) is a noble gas that comprises 0.93 percent of the earth's atmosphere. Colorless, odorless, tasteless and nontoxic, argon forms no known chemical compounds. A specific gravity of 1.38 makes argon 25 percent heavier than air. At atmospheric pressure, it becomes a liquid at -302°F (-186°C). Noncorrosive and non-flammable, argon also exhibits low thermal conductivity and slight solubility in water. This highly stable chemical element is colorless, odorless, tasteless and nontoxic in both its liquid and gaseous forms. Argon is inert under most conditions and forms no confirmed stable compounds at room temperature. The creation of argon hydrofluoride (HArF), a metastable compound of argon with fluorine and hydrogen, was first reported by researchers at the University of Helsinki in 2000. Although the neutral ground-state chemical compounds of argon are presently limited to HArF, argon can form clathrates with water when atoms of it are trapped in a lattice of the water molecules. Also argon-containing ions e.g. ArH+ and excited state complexes e.g. ArF are well known. Theoretical calculations on computers have shown several argon compounds that should be stable but for which no synthesis routes are currently known.

Applications

Argon is used in incandescent lighting and other applications in which diatomic nitrogen is not sufficiently inert. Argon will not react with the filament of light bulbs even at high temperatures. Other uses: Argon is used as an inert gas shield in many forms of welding, including metal inert gas welding and tungsten inert gas welding; as the gas of choice for the plasma used in ICP spectroscopy; as a non-reactive blanket in the manufacture of titanium and other reactive elements; as a protective atmosphere for growing silicon and germanium crystals; as a gas for use in plasma globes; as an inert gas for partial pressure heat treat furnaces; and as a gas for thermal insulation in energy efficient windows. Argon-39 has been used for a number of applications, primarily ice coring. It has also been used for ground water dating. Cryosurgery procedures such as cryoablation use liquified argon to destroy cancer cells. Liquid argon is used in calorimetry in experimental particle physics. Argon is used in technical scuba diving to inflate a dry suit, because it is inert and has low thermal conductivity. Blue argon lasers are used in surgery to weld arteries, destroy tumors, and to correct eye defects. Due to its inert qualities, it is commonly used by museum conservators to protect old materials or documents, which are prone to gradual oxidation in the presence of air. Argon is used to keep open bottles of wine from oxidizing, and is used in a number of dispensing units and keeper cap systems. Argon is used in winemaking as barrels are often topped off with the gas to displace oxygen, thus preventing the wine from turning to vinegar during the aging process. Argon is used in surgery in a procedure called "argon enhanced coagulation" which is a form of argon plasma beam electrosurgery. The procedure carries a risk of producing gas embolism in the patient and has resulted in the death of one person via this type of accident. Its triple point temperature of 83.8058 K is a defining fixed point in the International Temperature Scale of 1990.

Carbon Dioxide (CO2)

Carbon Dioxide, CO2, is a tasteless,colorless, odorless, nonflammable, liquefied gas. Carbon dioxide is an integral part of the basic life cycle in nature. It is exhaled by humans and animals, then used by plants to help them grow. Plants, in turn, release oxygen, which people depend on for survival. Unlike atmospheric gases, air separation is not the primary source of carbon dioxide. Though sometimes it is derived from directly combusting a fuel, the most economical way to produce carbon dioxide is to recover it as a byproduct from other companies' manufacturing processes or from natural wells. Then it is purified and liquefied and sold to our customers worldwide. Atmospheric carbon dioxide derives from multiple natural sources including volcanic outgassing, the combustion of organic matter, and the respiration processes of living aerobic organisms; man-made sources of carbon dioxide come mainly from the burning of various fossil fuels for heating, power generation and transport use. It is also produced by various microorganisms from fermentation and cellular respiration. Plants convert carbon dioxide to oxygen during a process called photosynthesis, using both the carbon and part of the oxygen to construct carbohydrates. The resulting gas, oxygen, is released into the atmosphere by plants, which is subsequently used for respiration by heterotrophic organisms, forming a cycle.

Applications

Carbon Dioxide (CO2) has many different applications. Carbon Dioxide is primarily used for carbonating beverages; everything from sodas to carbonated water rely on CO2. The carbonation process is simple, gaseous CO2 is injected into the soda mixture to produce a carbonated beverage. Carbon Dioxide is mixed with Argon and or Helium in different quantities to produce an inert gas shield for welding. Carbon Dioxide forms Dry Ice in its solid form and has numerous applications.

Helium (He)

Helium (helios, meaning "sun") is a colorless, odorless, tasteless chemical element, the least reactive of the nearly inert noble gas elements. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. At temperatures near absolute zero and standard pressure, helium exists as a superfluid, a nearly frictionless phase of matter with unusual properties. After hydrogen, helium is the second lightest element and also the second most abundant element in the universe. It was created during big bang nucleosynthesis and to a lesser extent from nuclear fusion of hydrogen in stars. First detected in 1868 by French astronomer Pierre Janssen as an unknown yellow spectral line signature in the light of a solar eclipse, helium was separately identified as a new element later that year by English astronomer Norman Lockyer. On Earth, helium is relatively rare, and was not detected until 1895 in mineral samples. It is primarily a product of the radioactive decay of much heavier elements, which emit helium nuclei called alpha particles. Its presence in natural gas, the only place it is found in significant amounts, was identified in 1905. Commercially it is extracted at low temperatures from natural gas by fractional distillation. Natural gas from different wells on different continents varies greatly in helium gas content. Helium is used in cryogenics, as a deep-sea breathing gas, for inflating balloons and airships, and as a protective gas for many industrial purposes, such as arc welding. Inhaling a small amount of the gas temporarily changes the timbre of a person's voice; however, caution must be exercised as helium is an asphyxiant.

Applications

Helium is used for many purposes that require some of its unique properties, such as its low boiling point, low density, low solubility, high thermal conductivity, or inertness. Pressurized helium is commercially available in large quantities. Because it is lighter than air, airships and balloons are inflated with helium for lift. In airships, helium is preferred over hydrogen because it is not flammable and has 92.64% of the lifting power of the alternative hydrogen. For its low solubility in water, the major part of human blood, air mixtures of helium with oxygen and nitrogen (Trimix), with oxygen only (Heliox), with common air (heliair), and with hydrogen and oxygen (hydreliox), are used in deep-sea breathing systems to reduce the high-pressure risk of nitrogen narcosis, decompression sickness, and oxygen toxicity. At extremely low temperatures, liquid helium is used to cool certain metals to produce superconductivity, such as in superconducting magnets used in magnetic resonance imaging. Helium at low temperatures is also used in cryogenics. For its inertness and high thermal conductivity, helium is used as a coolant in some nuclear reactors, such as pebble-bed reactors. Helium is used as a shielding gas in arc welding processes on materials that are contaminated easily by air. It is especially useful in overhead welding, because it is lighter than air and thus floats, whereas other shielding gases sink. Because it is inert, helium is used as a protective gas in growing silicon and germanium crystals, in titanium and zirconium production, in gas chromatography, and as an atmosphere for protecting historical documents. This property also makes it useful in supersonic wind tunnels. In rocketry, helium is used as an ullage medium to displace fuel and oxidizers in storage tanks and to condense hydrogen and oxygen to make rocket fuel. It is also used to purge fuel and oxidizer from ground support equipment prior to launch and to pre-cool liquid hydrogen in space vehicles. For example, the Saturn V booster used in the Apollo program needed about 13 million cubic feet (370,000 m³) of helium to launch. The gain medium of the helium-neon laser is a mixture of helium and neon. Because it diffuses through solids at a rate three times that of air, helium is used to detect leaks in high-vacuum equipment and high-pressure containers. Because of its extremely low index of refraction, the use of helium reduces the distorting effects of temperature variations in the space between lenses in some telescopes. The age of rocks and minerals that contain uranium and thorium, radioactive elements that emit helium nuclei called alpha particles, can be discovered by measuring the level of helium with a process known as helium dating. Because helium alone is less dense than atmospheric air, it will change the timbre (not pitch) of a person's voice when inhaled. However, inhaling it from a typical commercial source, such as that used to fill balloons, can be dangerous due to the number of contaminants that may be present. These could include trace amounts of other gases, in addition to aerosolized lubricating oil. The high thermal conductivity and sound velocity of helium is also desirable in thermoacoustic refrigeration. The inertness of helium adds to the environmental advantage of this technology over conventional refrigeration systems which may contribute to ozone depleting and global warming effects.

Hydrogen (H2)

Hydrogen, or H2, is the lightest of all gases. Commonly found in nature in compounds with other elements, it is the most abundant element in the universe. Hydrogen is a component of water, minerals and acids, as well as an essential part of all hydrocarbons and essentially all other organic substances. In fact, 98 percent of the known universe - most notably the sun and stars - consists of hydrogen. Colorless, odorless, tasteless and nontoxic, hydrogen exists as a gas at atmospheric temperatures and pressures. A stable molecule because of its high bond strength, hydrogen becomes reactive at elevated temperatures or with the aid of catalysts. When cooled to its boiling point of -423°F (-253°C), hydrogen becomes a liquid that is approximately 93 percent lighter than water. All other gases - except helium - become solids at this temperature. Hydrogen is flammable and burns in air with a pale blue, almost invisible flame. In its gaseous form, hydrogen dissipates quickly. These unique properties call for strict safety measures in hydrogen use and storage.

Applications

Large quantities of H2 are needed in the petroleum and chemical industries. The largest application of H2 is for the processing ("upgrading") of fossil fuels, and in the production of ammonia. The key consumers of H2 in the petrochemical plant include hydrodealkylation, hydrodesulfurization, and hydrocracking. H2 has several other important uses. H2 is used as a hydrogenating agent, particularly in increasing the level of saturation of unsaturated fats and oils (found in items such as margarine), and in the production of methanol. It is similarly the source of hydrogen in the manufacture of hydrochloric acid. H2 is also used as a reducing agent of metallic ores. Apart from its use as a reactant, H2 has wide applications in physics and engineering. It is used as a shielding gas in welding methods such as atomic hydrogen welding. H2 is used as the rotor coolant in electrical generators at power stations, because it has the highest thermal conductivity of any gas. Liquid H2 is used in cryogenic research, including superconductivity studies. Since H2 is lighter than air, having a little more than 1/15th of the density of air, it was once widely used as a lifting agent in balloons and airships. However, this use was curtailed after the Hindenburg disaster convinced the public that the gas was too dangerous for this purpose. Hydrogen is still regularly used for the inflation of weather balloons. Hydrogen's rarer isotopes also each have specific applications. Deuterium (hydrogen-2) is used in nuclear fission applications as a moderator to slow neutrons, and in nuclear fusion reactions. Deuterium compounds have applications in chemistry and biology in studies of reaction isotope effects. Tritium (hydrogen-3), produced in nuclear reactors, is used in the production of hydrogen bombs, as an isotopic label in the biosciences, and as a radiation source in luminous paints. The triple point temperature of equilibrium hydrogen is a defining fixed point on the ITS-90 temperature scale.

Nitrogen (N2)

Nitrogen, or N2, is a diatomic gas which comprises 78 percent of the earth's atmosphere. In addition to air, nitrogen is found in the protein matter of all life forms, in some natural gas-hydrocarbon deposits, and in many organic and inorganic compounds. Colorless, odorless, tasteless, and nontoxic, nitrogen exists as a non-flammable gas at atmospheric temperatures and pressures. A specific gravity of .9669 makes nitrogen slightly lighter than air. When cooled to its boiling point of -320°F, nitrogen becomes a colorless liquid which can, in turn, be compressed into a colorless, crystalline solid. It is only slightly soluble in water and most other liquids, and is a poor conductor of heat and electricity. Most uses of gaseous nitrogen depend on its inert characteristics. At high temperatures and pressures, however, it will combine with some reactive metals (such as lithium and magnesium) to form nitrides, as well as with some gaseous elements such as hydrogen and oxygen.

Applications

Nitrogen gas has a wide variety of applications, including serving as an inert replacement for air where oxidation is undesirable; To preserve the freshness of packaged or bulk foods (by delaying rancidity and other forms of oxidative damage) In ordinary incandescent light bulbs as an inexpensive alternative to argon On top of liquid explosives for safety The production of electronic parts such as transistors, diodes, and integrated circuits Dried and pressurized, as a dielectric gas for high voltage equipment The manufacturing of stainless steel Use in military aircraft fuel systems to reduce fire hazard, see inerting system Filling automotive and aircraft tires due to its inertness and lack of moisture or oxidative qualities, as opposed to air, though this is not necessary for consumer automobiles. Nitrogen molecules are less likely to escape from the inside of a tire compared to the traditional air mixture used. Air consists mostly of nitrogen and oxygen. Nitrogen molecules have a larger effective diameter than oxygen molecules and therefore diffuse through porous substances more slowly. A further example of its versatility is its use as a preferred alternative to carbon dioxide to pressurize kegs of some beers, particularly thicker stouts and Scottish and English ales, due to the smaller bubbles it produces, which make the dispensed beer smoother and headier. A modern application of a pressure sensitive nitrogen capsule known commonly as a "widget" now allows nitrogen charged beers to be packaged in cans and bottles. Molecular nitrogen, a diatomic gas, is apt to dimerize into a linear four nitrogen long polymer. This is an important phenomenon for understanding high voltage nitrogen dielectric switches because the process of polymerization can continue to lengthen the molecule to still longer lengths in the presence of an intense electric field. A nitrogen polymer fog is thereby created. The second virial coefficient of nitrogen also shows this effect as the compressibility of nitrogen gas is changed by the dimerization process at moderate and low temperatures. Liquid nitrogen (liquid density at the triple point is 0.807 g/mL) is produced industrially in large quantities by fractional distillation of liquid air and is often referred to by the abbreviation, LN2. It is a cryogenic fluid which is potentially capable of causing instant frostbite on contact with living tissue (see precautions). When appropriately insulated from ambient heat, liquid nitrogen serves as a compact and readily transported source of nitrogen gas without pressurization. Further, its ability to maintain temperatures far below the freezing point of water (it boils at 77 K, which equals -196 °C or -320 °F) makes it extremely useful in a wide range of applications as an open-cycle refrigerant, including; the immersion freezing and transportation of food products the cryopreservation of blood, reproductive cells (sperm and egg), and other biological samples and materials the cryonic preservation of humans and pets in the unproven hope of future reanimation. in the study of cryogenics for demonstrations in science education as a coolant for highly sensitive sensors and low-noise amplifiers in dermatology for removing unsightly or potentially malignant skin lesions such as warts and actinic keratosis as a cooling supplement for overclocking a central processing unit, a graphics processing unit, or another type of computer hardware as a cooling medium during machining of high strength materials. as the working fluid in a binary engine as a means of final disposition of the dead, known as promession.

Oxygen (O2)

Oxygen, or O2, which comprises 21 percent of the earth's atmosphere, supports life and makes combustion possible. The most abundant of allelements on earth, oxygen comprises 85 percent of its oceans and, as a component of most rocks and minerals, 46 percent of its solid crust. In addition, it constitutes 60 percent of the human body. Colorless, odorless and tasteless, oxygen has poor solubility in water. A specific gravity of 1.105 makes it slightly heavier than air. When cooled to its boiling point of -297°F (-183°C), oxygen becomes a transparent, pale blue liquid that is slightly heavier than water. Oxygen reacts with all elements, except inert gases, to form compounds called oxides. The rate of reaction - known as oxidation - varies. For example, magnesium oxidizes very rapidly, igniting spontaneously in air. However, noble metals, such as gold and platinum, oxidize only at very high temperatures. Although oxygen itself is nonflammable, it enhances combustion and enables all materials that are flammable in air to burn much more vigorously. These combustion-supporting properties account for its use in many industrial applications.

Applications

Uptake of oxygen from the air is the essential purpose of respiration, so oxygen supplementation has found use in medicine (as oxygen therapy). People who climb mountains or fly in non-pressurized aeroplanes sometimes have supplemental oxygen supplies; the reason is that increasing the proportion of oxygen in the breathing gas at low pressure acts to augment the inspired oxygen partial pressure nearer to that found at sea-level. A notable application of oxygen as a very low-pressure breathing gas, is in modern spacesuits, where use of nearly pure oxygen at a total ambient pressure of about one third normal, results in normal blood partial pressures of oxygen. This trade-off of breathing gas content and needed pressure is important for space applications, because the issue of flexible spacesuits working at Earth sea-level pressures remains a technological challenge of aerospace technology. Oxygen is used in welding (such as the oxyacetylene torch), and in the industrial production of steel and methanol. Also, liquid oxygen finds use as a classic oxidizer in rocket propulsion. Oxygen presents two spectrophotometric absorption bands peaking at the wavelengths 687 and 760 nanometers. Some scientists have proposed to use the measurement of the radiance coming from vegetation canopies in those oxygen bands to characterize plant health status from a satellite platform. This is because in those bands, it is possible to discriminate the vegetation's reflectance from the vegetation's fluorescence, which is much weaker. The measurement presents several technical difficulties due to the low signal to noise ratio and due to the vegetation's architecture, but it has been proposed as a possibility to monitor the carbon cycle from satellites on a global scale. Oxygen, as a supposed mild euphoric, has a history of recreational use . However, the reality of a pharmacological effect is doubtful being a metabolic boost the most plausible explanation. Controlled tests of high oxygen mixtures in diving and other activities, even at higher than normal pressures, demonstrated no particular effects on humans other than promotion of an increased tolerance to aerobic exercise. In the 19th century, oxygen was often mixed with nitrous oxide to temper its analgesic effect. A stable 50% gaseous mixture (Entonox) is commonly used in medicine today as an analgesic. However, the common basic anaesthetic mixture is 30% oxygen with 70% nitrous oxide; the pain-suppressing effects, obviously, are due to the nitrous oxide and not to oxygen.

A1025-Trimix

A1025 gas blend is a specially formulated mixture of argon, helium and carbon dioxide designed for joining a variety of coated steels. The A1025 gas blend reduces the spatter and porosity problems commonly associated with the welding of coated steels. Both galvanized and galvannealed materials can be successfully joined without the need for additional post-weld cleanup and rework. A1025 blend is superior to two part gas blends for welding coated steels because of the increased arc stability it provides. The addition of helium to this gas blend also makes higher travel speed possible in a number of applications. While optimized for pulsed-GMAW, the A1025 blend performs well in all types of metal transfer (short-circuiting, pulsed, and conventional spray).

C-15

C-15 Gas Blend. This blend has been used for a variety of applications on carbon and low-alloy steels. In the short-circuit mode of transfer, maximum productivity on thin gauge metals can be achieved with this blend. This is done by minimizing the excessive melt-through tendency of higher carbon dioxide mixes, while increasing deposition rates and travel speeds. As the carbon dioxide percentages are lowered from the 20% range (maximum spray arc levels), improvements in deposition efficiency occur due to decreasing spatter loss. This blend will support the spray arc mode of transfer.

C-25 (75/25)

C-25 Gas Blend. This blend is commonly used for GMAW with short-circuiting transfer on low carbon steel. It was formulated to provide optimum droplet frequency on short-circuiting transfer using .035 and .045 diameter wire. C-25 operates well in high current applications on heavy base metal. It promotes good arc stability, weld pool control, and weld bead appearance. This blend will not support the spray type mode of metal transfer.

HE-25

He-25 Gas Blend. This blend is used for welding nonferrous base metals when an increase in heat input is needed and weld bead appearance is of primary importance.The HE-25 argon/helium blends are used in a wide variety of Gas Tungsten Arc Welding (GTAW or TIG) applications where increased heat input to the base material is desirable while maintaining favorable arc starting and stability characteristics. The HE-25 blends can also be used for Gas Metal Arc Welding (GMAW or MIG) of thick aluminum sections and for other non-ferrous materials where additional heat input to the base material enhances welding performance.

Propane (C3H8)

Propane (C3H8) is a colorless, flammable, liquified gas with a natural gas odor. The flame temperature of the oxy-propane flame is lower than acetylene flames. The primary flame releases low BTU when compared to acetylene, which increases preheat time. Propane is commonly used by scrap yards for cutting carbon steel, where the cut quality is not critical. Where cut qualtiy is not a concern, propane may be a cost-effective fuel gas. Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. It is derived from other petroleum products during oil or natural gas processing. It is commonly used as a heat source for engines, barbecues, and homes. Its name was derived from propionic acid. When commonly sold as fuel, it is also known as liquified petroleum gas (LPG or LP-gas) and can be a mixture of propane with smaller amounts of propylene, butane and butylene. The odorant ethanethiol is also added so that people can easily smell the gas in case of a leak.

Applications

It is used as fuel in cooking on many barbecues, portable stoves, and in motor vehicles. The ubiquitous 5-gallon steel container has been dubbed the "barbecue bottle." Propane powers some locomotives, buses, forklifts, and taxis and is used for heat and cooking in recreational vehicles and campers. In many rural areas of North America, propane is also used in furnaces, stoves, water heaters, laundry dryers, and other heat-producing appliances. 6.5 million American households use propane as their primary heating fuel. Commercially-available "propane" fuel, or LPG, is not pure. Typically in the USA and Canada, it is primarily propane (at least 90%), with the rest mostly butane and propylene, plus odorants. This is the HD5 standard, written for vehicle fuels; note that not all product labeled "propane" conforms to this standard. In Mexico, the butane content is much higher. In North America, local delivery trucks called "bobtails" fill up large tanks that are permanently installed on the property (sometimes called pigs), or other service trucks exchange empty bottles of propane with filled bottles. The bobtail is not unique to the North American market, though the practice is not as common elsewhere, and the vehicles are generally referred to as tankers. In many countries, propane is delivered to consumers via small or medium-sized individual tanks. Propane is the fastest growing fuel source in the Third World, especially in China and India. Its use frees up the huge rural populations from time-consuming ancient chores such as wood gathering and allows them more time to pursue other activities, such as increased farming or educational opportunities. Hence it is sometimes referred to as "cooking gas." On an aside, North American barbecue grills powered by propane cannot be used overseas. The "propane" sold overseas is actually a mixture of propane and butane. The warmer the country, the higher the butane content, commonly 50/50 and sometimes reaching 75% butane. Usage is calibrated to the different-sized nozzles found in non-U.S. grills. Americans who take their grills overseas — such as military personnel — can find U.S.-specification propane at AAFES military post exchanges. North American industries using propane include glass makers, brick kilns, poultry farms, and other industries that need portable heat. Additionally, most of the entire North American chemical industry uses propane to power their huge facilities that crack or distill industrial chemical products. Propane is also instrumental in providing off-the-grid refrigeration, also called gas absorption refrigerators. Made popular by the Servel company, propane-powered refrigerators are highly efficient, do not require electricity, and have no moving parts. Refrigerators built in the 1930s are still in regular use, with little or no maintenance. However, certain Servel refrigerators are subject to a recall for CO poisoning. In highly purified form, propane (R-290) can serve as a direct replacement in mechanical refrigeration systems designed to use R-12, R-22 or R-134a chloro- or fluorocarbon based refrigerants. Today, the Unilever Ice Cream company and others are exploring the use of environmentally friendly propane as a refrigerant. As an added benefit, users are finding that refrigerators converted to use propane are 9-15% more energy efficient Propane is also being used increasingly for vehicle fuels. In the U.S., 190,000 on-road vehicles use propane, and 450,000 forklifts use it for power. It is the third most popular vehicle fuel in America, behind gasoline and diesel. In other parts of the world, propane used in vehicles is known as autogas. About 9 million vehicles worldwide use autogas. The advantage of propane is its liquid state at room temperature and moderate pressure. This allows fast refill times, affordable fuel tank construction, and ranges comparable to (though still less than) gasoline. Meanwhile it is noticeably cleaner (both in handling, and in combustion), results in less engine wear (due to carbon deposits) without diluting engine oil (often extending oil-change intervals), and until recently was a relative bargain in North America. Octane rating is noticeably higher, which could result in more power, though exploiting this extra "octane" requires significant engine modification. However, public filling stations are still rare. Many converted vehicles have provisions for topping off from "barbecue bottles." Purpose-built vehicles are often in commercially-owned fleets, and have private fueling facilities. Propane is generally stored and transported in steel cylinders as a liquid with a vapour space above the liquid. The vapour pressure in the cylinder is a function of temperature. When gaseous propane is drawn at a high rate the latent heat of vaporisation required to create the gas will cause the bottle to cool. (This is why water often condenses on the sides of the bottle and then freezes). In extreme cases this may cause such a large reduction in pressure that the process can no longer be supported. In addition, the lightweight, high-octane compounds vaporize before the heavier, low-octane ones. Thus the ignition properties change as the tank empties. For these reasons, the liquid is often withdrawn using a dip tube.

Propylene (C3H6)

Propylene (C3H6) is a colorless, flammable, liquified gas with a faintly sweet odor. It has high heat release in its primary and secondary flames. The heat release in the primary flame cone is similar to acetylene. The BTU capacity of the outer flame is superior to that of acetylene. Propylene combines the qualities of an acetylene flame with the secondary heating capacity of propane. The fuel gas burns hotter than propane; however, the cutting speed should be calculated on a case-by-case-basis before choosing this as the most economical choice as your fuel gas.