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May - June 2003

superman1 A Powerful Element
How Manufacturers Can Use 
Krypton to Increase Energy Efficiency

by Tom Gallagher, Matthew Adams and Richard Turner

Top: Spectra Gases uses this cylinder to visually show people how different gases are affected when an electrical charge is put across them. Current political and economic influences are causing increased demand for improved energy consumption efficiency in worldwide markets, especially in North America and Europe. Government agencies such as the Department of Energy are modifying regulatory environments to induce energy users and product manufacturers to improve energy consumption efficiency. In the fenestration industry, door and window associations and their members have responded to government-sponsored initiatives and have increased the Energy Star® ratings for their insulating glass units (IGU) continually.

Advantages of Krypton Gas
Krypton offers very low thermal conductivity. When it is used as an IGU fill gas, the R value is increased, thus increasing energy efficiency. Currently, approximately 2 percent of all IGUs that are produced in North America and Europe are filled with krypton gas or a krypton/argon gas mixture. Krypton is very expensive. In today’s market, the average price of pure krypton gas is between $0.40 and $0.65 per liter, depending on annual volumes. Like any commodity, krypton gas pricing is subject to fluctuations caused by changes in supply and demand. Long-term forecasts indicate that the demand for increased IGU energy efficiency will affect krypton pricing, as the fenestration industry becomes a more significant consumer of krypton gas. 

The R-20 Gas Recovery System has two main parts: the first is the FDR-Kr Gas filling Unit which is the smaller unit sitting on top of the larger R-20 System. Common IGU gas-filling procedures cause a large percentage of the expensive krypton gas to be exhausted back into the atmosphere. After a year of testing, both in the lab and on the production floor, Spectra Gases has confirmed that IGU manufacturers (when using optimized laminar flow fill procedures) exhaust 40 to 50 percent of the fill gas (argon, krypton or xenon) from the IGU exhaust port during the gas-fill process. For example, in a dual-lite window with the dimensions of 24 by 24 inches by 0.375 inches, the internal volume (216 cubic inches multiplied by a correction factor of 0.01639 liters per cubic inch) is 3.5 liters. Laminar flow testing has shown that 6 to 7 liters of gas are used to fill a 3.5-liter IGU to a more than 90 percent concentration with 2.5 to 3.5 liters escaping into the atmosphere.

First-of-its-Kind Invention 
For more than 20 years, Spectra Gases has designed and installed gas recovery systems to help major space programs and light bulb manufacturers around the world reduce expensive gas costs. Spectra Gases is now offering this crossover gas recovery technology to meet the needs of the IGU market. In collaboration with Advanced Photonics Inc., a manufacturer of gas handling systems, Spectra Gases has introduced the world’s first gas recovery device for IGU manufacturers: The R-20 Gas Recovery System. The initial R-20 system installation was completed at Thermal Industries Inc. in Pittsburgh in early 2003.

“We are always seeking ways to ensure our customers the confidence that the products we provide achieve the highest performance,” said Bill Van Kirk, design engineer for Thermal Industries Inc. “The implementation of these two machines (R-20 and RSGkr) has allowed us to exceed the current standard and set new benchmarks within the fenestration industry while maintaining an efficient cost structure. With the advent of non-destructive testing, ga- filled insulating units will continue to grow in popularity.”

The R-20 Gas Recovery System is designed to recover virtually all of the expensive krypton and/or xenon fill gas that is exhausted from IGUs during the gas-filling procedure. The recovered gas is compressed into cylinders for reclamation and re-purified using the company’s gas distillation technology. This re-purified gas is supplied back to the window manufacturer for re-use as pure krypton gas at almost half the cost of the original material.

The R-20 provides maximum cost savings for krypton/xenon gas-filled energy-efficient windows and can stabilize commodity price fluctuations for krypton or xenon gas. This new crossover recovery technology reduces the average krypton gas price to the IGU manufacturer by 10 to 25 percent, depending on annual gas volumes. It should be noted that there are certain minimum annual gas volume requirements before the R-20 becomes economically viable for the IGU manufacturer. 

The R-20 Gas Recovery System comes complete with FDR Design gas-filling units which are designed specifically to interface with the recovery device. The system can be configured to fill up to four triple-lite windows or eight dual-lite windows at one time. 

“It is exciting to witness the maturing of inert gas-filled high-performance windows. It seems like we started down this path just yesterday, while in fact 15 odd years have gone by,” said Randi Ernst, president of FDR Design of Buffalo, Minn. “Today argon-filled high-performance insulating glass accounts for approximately 70 percent of all residential units produced, so it was inevitable that someone would start looking at the even higher performance levels that krypton and xenon can achieve.” 

Tom Gallagher and Matthew Adams are vice president and equipment manager respectively for Spectra Gases based in Branchburg, N.J., and Richard Turner is vice president of Advanced Photonics Inc. based in Ronkonkoma, N.Y.

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