Deriving from the Greek neos, meaning ‘new one’, neon was first discovered in 1898 by Sir William Ramsay. Decades later the French engineer and chemist, George Claude, discovered that applying an electric charge caused a sealed neon tube to glow.
This discovery was subsequently patented in 1915 and is still used today.
However, as Praxair states, there are a growing gamut of new applications: “Commonly known as a fill gas for colourful neon signs in outdoor advertising displays, neon’s other uses include plasma TVs and several laser applications including medical and semiconductor chip manufacturing.”
Neon is classified as a rare or speciality gas as it constitutes 0.018% volume of dry air. Although present in minerals and abundant in the cosmos, neon is commercially sourced via the cryogenic liquefaction and fractional distillation of air.
Currently daily global production levels of neon sit at approximately 300 million litres. Furthermore, with a relatively low boiling point of -246.1°C, it is obtained through air separation in conjuncton with liquid nitrogen production. Over 60% is sourced from the former Soviet Union.
Praxair keenly outlines the advantages of neon, stating, “Liquid neon has properties unique among other low-temperature cryogenic fluids in that its latent heat of vaporisation is over three times that of hydrogen and 41 times that of helium on a BTU/gallon ratio basis. It also has the greatest gas-to-liquid expansion ratio of the atmospheric gases.” This ratio translates to one liquid litre matching an equivalent 1,445 gas litres at room temperature.
Commonly, neon is supplied in compressed cylinders that contain from 25 to 8,000 gaseous litres. It is also supplied as a liquid in 200 litre dewars and in tube trailers with up to 3 million gaseous litres.
Furthermore, due to the monatomic, inert nature of neon, it is compatible with a range of materials including brass, stainless steel, aluminium, zinc, copper, as well as various plastics and elastomers.
Neon is largely so adaptable thanks to its inherent safety. Linde Speciality Gases division reflects this having served it a corresponding ‘A’ safety rating. Similarly, Advanced Speciality Gases, Inc. also defined it as a stable, non-toxic product.
Bright future markets
As technologies change, so does neon’s prospects. Perhaps most exciting is the future of neon in combination with other gases. In particular helium/neon (HeNe) lasers are answering increasing demand from interferomtery, precision measurement, holography and hematology.
Air Liquide argues that the inertness of the noble gases, “makes them very valuable for certain applications.” Indeed, neon is a key component within Linde’s Lung Diffusion Gases range which is so valuable in pulmonary function testing. In this instance, neon is used in place of helium to determine lung volume.
July 2010 saw neon used in a particle physics breakthrough. The SLAC National Accelerator Laboratory in Menlo Park, California created hollow neon atoms using an X-ray laser.
Linda Young, Director of X-ray Science Division at Argonne National Laboratory in Illinois and experiment leader, remarked in a statement, “It’s a billion times more intense than any other X-ray source available before. You need to understand how this ultra intense X-ray source will interact with matter. If you do it with something simple, you can see every step of the process.”
Looking still further afield, Praxair notes, “The space program uses liquid neon as a coolant for ultra-sensitive infrared imaging and detection equipment and for creating deep-space temperatures during satellite testing.”
Meanwhile, suppliers such as EGL Neon are optimistic that neon will still play a crucial role in lighting, despite the rise of LED devices.
Dr Bernard Diffin, Head of Product Development at The EGL Company, Inc, said, “In most instances neon based illumination systems still provide superior performance in terms of ‘light out for dollar in’ – particularly when we take into account relatively recent advances in the areas of phosphor and transformer technologies.”