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Specialty Gases

Pure Gases

Helium, argon, nitrogen, hydrogen, air and oxygen are all available in many different grades from Industrial to Research. Impurities can contaminate your instrument columns and reduce the sensitivity of your detectors. Protect these critical components and maximize your analytical accuracy by only using high quality pure gas appropriate for your application from Aramax, Inc.

Rare Gases

The so-called "rare" gases Neon (Ne), Krypton (Kr) and Xenon (Xe), are present in air in very low concentrations. Like the other "noble" or "inert" gases, helium (He), argon (Ar) and radon (Rn), Neon, Krypton and Xenon remain in the air because they do not combine with other materials to form solid or liquid compounds. All of these gases are monatomic. Neon, Krypton and Xenon are valued for their light emitting properties when electrically charged. Krypton and Xenon are also valued for their total inertness coupled with high molecular weight (83.80 and 131.30, respectively). Krypton and Xenon are about two to three times as heavy as argon (molecular weight 39.95) and approximately three to four times as heavy as nitrogen (molecular weight 28.0) which is used as in inert gas in many applications, but is not a true inert gas. These properties are put to good use in multi-pane windows to reduce heat loss due to convection between the panes; and in light bulbs, where their high molecular weight slows evaporation of the hot tungsten filament, leading to longer useful operating life. Krypton and Xenon have also been considered for a more exotic application - as the propulsion gas for deep space exploration using ion engines. Neon, Krypton and Xenon can be economically recovered by adding additional purification steps in large air separation plants or ammonia production plants (which use large amounts of air as a raw material). The boiling point of Neon is significantly lower than nitrogen (lower than all the gases except helium and hydrogen). It can be used as a very low temperature working fluid in refrigeration cycles. Neon can be recovered from large nitrogen plants as well as multi-product air separation units. Krypton and Xenon have higher boiling points than oxygen, from which they can be separated by distillation in air separation plants. When these products are recovered from ammonia plant purge gas, the neon must be separated from hydrogen and nitrogen, and the krypton and xenon from methane. All of the naturally inert or "noble" gases are members of "Group 18" of the Periodic Table. Group 18 materials have a complete outermost electron shell; the "valence" shell that is highly involved in the formation of compounds. Moving down the Periodic Table from Helium, to Neon, Argon, Krypton, Xenon and Radon, the valence shells are located further from the nucleus, above the previous element's valence shell. Helium has two valence electrons, the other noble gases have eight.

Lighting:

Neon is commonly recognized as the gas that produces the glow in "neon" lights (which often contain other gases as well). Neon's natural red color can be turned into a wide range of effective decorative lighting colors by mixing neon with other gases, by using colored glass tubes or by depositing fluorescent powder coatings inside the glass tubes. Neon is also used to produce a red glow in indicator lamps and lasers. Krypton is used in halogen sealed beam headlights to increase light output by allowing thinner filaments to be used with acceptable useful lifetimes. Krypton is also used in in lasers, in particular mixed with fluorine to create an "excimer" mixture that is a precursor to a molecule which exists in the excited state but not in the ground state. In excimer lasers, the gas mixture is pulsed to form short-lived excited molecules which release energy by light emission as the constituents return to the ground state. Krypton-fluorine excimer lasers produce high-power ultraviolet light used in eye surgery. Other applications are sterilization of fluids and lithographic fabrication of semiconductors. Xenon has a light spectrum that is much wider than neon or krypton and Xenon, with an overall bluish hue that is perceived as being similar to "daylight". It is used in high-intensity aviation approach lights, in high-efficiency incandescent bulbs for automotive and stage lighting uses, in plasma display panels, in operating room and internal examination lighting, and in ultraviolet lasers.

Construction:

Argon and Krypton are used as a premium filler gases for high-efficiency dual-pane (and triple pane) windows. Argon is about one-third heavier than nitrogen or dry air, and Krypton is twice as heavy as Argon. They may be used individually or in a mixture. These heavier filler gases minimize heat transmission by convective movement of the filler gas between the panes of glass. The insulating value of the window (measured by R value) is roughly proportional to the molecular weight of the filler gas, holding other possible construction differences such as the impact of high efficiency (Low E) glass coatings and triple versus dual-pane construction constant. Noise transmission through windows is also reduced as the molecular weight of the filler gas increases. Argon is about 5 times as expensive as dry nitrogen, but so little is used in a window that the benefits of using it are easily justified. Argon has become the preferred gas to use in most multi-paned windows. Krypton costs much more than argon, often about 100 times as much for the same volume. This price disparity is mainly due to the much lower concentration of Krypton than Argon in air. Only a small number of air separation plants process enough air to make production of Krypton economically attractive. Low Temperature Refrigeration: Neon, with a boiling point lower than all the gases except helium and hydrogen, can be used as a very low temperature refrigerant. On a volume basis, Neon has 3 times the refrigerating capacity of liquid hydrogen and over 40 times the refrigerating capacity of liquid helium.

Grades

A full range of purities - for certain applications, up to 99.9999 percent - is available. Available Purities -- C.P. Grade 99.5%, Instrument Grade 99.9%, Also available in higher purities: 99.99%, 99.995%, and 99.999%. Packaged by the cubic foot. Standard cylinder is 200 Cu. Ft.

Calibration Standards

Aramax, Inc. offers a complete line of gas calibration standards from a single source allowing you to save time and money by consolidating vendors and centralizing responsibility. Quantitative analytical measurements are a critical component in achieving accuracy in laboratory and manufacturing applications that include petrochemical processes, natural gas, environmental compliance, and health and safety programs. Where the measurement hardware is not calibrated, there can be no certainty in the measurements conducted. Enter calibration gases. The calibration gas standard establishes a known analyzer response to a certified chemical component concentration. This enables sample responses to be converted to a concentration whose accuracy can be determined. Before Aramax, Inc. can produce a calibration gas standard, specific information is required from the end-user. This information includes a list of components that make up the calibration gas: concentrations, units, balance gas, cylinder size, blend tolerance, and analytical accuracy. The task of standards selection usually shouldn’t be delegated or you may end up being expected to follow a set of requirements that don’t improve your processes, don’t reduce costs, or don’t assure safety and quality. Ultimately, the best people to select standards are ones that are knowledgeable about the work being performed.

Hydrocarbon Standards

The use of Hydrocarbon Standards allows accurate measurement of the heavier hydrocarbons fraction within a natural gas sample. This information then allows the hydrocarbon dew-point to be calculated, reassuring the gas transporter that condensation of the mixture will not take place in the gas pipeline.

Sulfur Standards

Fuel Gas Plants (Method 11 Hydrogen Sulfide mixtures) Miscellaneous (PPB & PPM Hydrogen Sulfide, Carbonyl Sulfide, Sulfur Dioxide, Methyl Mercaptan, Ethyl Mercaptan, Thiophene, Carbon Disulfide & Dimethyl Disulfide)

Atmospheric Standards

Certified and primary calibration gas standards are used for instrument calibration and other monitoring and measurement applications where either use of an EPA Protocol calibration standard is not required or an EPA Protocol standard is not available.

Equipment

Pressure Regulators For Specialty Gases: Selecting the right regulator for handling a specialty gas product is critical to maintaining the overall purity of the gas stream at the point of use. Ordinary industrial regulators are constructed of materials that may not be compatible with many specialty gases. Aramax is able to provide the best equipment for a given application and/or advice on the features and benefits to look for in specialty gas equipment. Materials in construction: It is important that all materials of construction in a specialty gas regulator (the “wetted surface” ) are compatible with the gas stream it is in contact with during use. Most regulators are made from stainless steel or brass but some are made from aluminium. Aluminium should not be used for oxygen or most corrosive gases. For higher purity gases, stainless steel is generally recommended. For inert gases, brass is often used. For most specialty gas products regulators made from machined bar stock are recommended over forged body regulators. Forged body regulators have wetted surfaces that are much rougher than machined bodies and those surfaces can trap trace components in the gas stream. Brass regulators may also be either chrome or electroless nickel-plated. In basic terms, gases that are corrosive or containing corrosive species of gas eg. SO2, H2S, Cl etc, require the use of stainless steel equipment. Non corrosive gases can be used satisfactorily with brass bodied regulators. Stainless steel is also the first choice when using the ultra pure grades of gases (>99.999%). The other materials used to construct a regulator are also important. The diaphragm and gauges as well as parts like seats, seals and other wetted surfaces should be compatible with the respective gas service. Stainless steel diaphragms are recommended for most specialty gas regulators. Neoprene diaphragms such as those used on industrial regulators should not be used. Single-Stage or Dual-Stage Regulators: There are some important differences between single stage and dual stage regulators. Single stage regulators drop the pressure to a lower pressure in a single step. Because the inlet pressure changes as a cylinder of gas is consumed, the outlet pressure on a single stage regulator changes. For many laboratory applications, a constant gas delivery pressure is required and dual stage regulators are recommended. Dual stage regulators differ from single stage regulators in that the inlet pressure is first dropped to a consistent lower pressure and that pressure is then regulated to the desired outlet pressure. Because there is much less drift in outlet pressure for dual stage regulators, they are recommended for most specialty applications.

Aramax, Inc.
8641 Wayfarer Ln, Houston, TX 77075
Phone: (713) 946-8305 Fax: (713) 946-8308

Specialty Gases

Gases

Standards

Instruments

Lighting:

Construction: