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Volume 6   Issue 7               August  2005


Gas Filling:  The Greatest Value in Improving IG Efficiency
by Kevin Zuege

The year is 2025 and a customer of yours just purchased a turn of the millennium home—a classic beauty from the year 2000 with an old concrete driveway that has been newly fitted with a hover pad for your no-emissions hover craft.

One problem–the new home still has its original windows, which were never energy efficient to begin with. Now the customer is worried about future costs.

With supply disruptions, the Earth’s diminishing oil reserve, war and other factors, there’s no telling what the cost of heating and cooling this classic home would be. After all, energy costs are only going up.

Currently, energy loss through residential windows and doors adds up to approximately $25 billion per year. As a result, homeowners and builders are learning to be more savvy when it comes to purchasing energy-efficient insulating glass (IG) units for new constructions and to replace old windows and doors. Hands-on, do-it-yourself television, websites and magazines are making it easier than ever for homeowners to make educated purchase-decisions.

Obviously, energy efficiency is dependent upon the materials and workmanship of the IG manufacturer. Using a combination of warm-edge spacer systems and low-E coatings is essential to ensure thermal performance and, more importantly, improved energy bills. One of the greatest values in improving thermal performance–gas filling–remains underutilized in the industry. 

“Less than 10 percent of the installed IG windows in North America are gas-filled and the rest are filled with air,” says Darcy Meyer, general manager of Besten Equipment Inc.

“For example, I replaced the windows in my home last year with gas-filled IG units and often make my neighbors jealous when comparing energy bills. It was such a drastic difference.”

Even though gas filling is underutilized, it is also thought to provide the greatest value, cost-wise, by improving thermal performance. The amount of argon used in filling a typical residential window costs about five cents, but yields approximately 10-15 percent additional energy savings.

When manufacturers make the decision to plunge into gas filling, many options abound: argon or krypton, timer fill or sensor fill, inline or offline? Here we hope to clarify some of the differences.

Filling Options
There are two popular types of gas filling, with an emerging third option. 

Timer Fill: This is the most prevalent option in the industry because of its relatively low capital cost. This system displaces air in a unit by pumping gas for a predetermined length of time at a specified low rate into the bottom of the unit. 

Sensor Fill: This method utilizes sensors that monitor exit gas while units are being filled. One type of system uses oxygen sensors to determine the lack of oxygen leaving the IG unit, while another uses a conductivity sensor to measure the percent of fill gas that replaces air inside the unit. 

Quik-Dose™ Liquid Fill: This is a patented technology from our company and Besten that first senses the size of the unit passing through and fills the unit with the precise amount of liquid argon for its size–all in fewer than 10 seconds. Liquid argon (post expansion) is also less expensive than compressed gas used in sensor or timer fill systems.

Production Equipment
Inline Gas Filling: Inline gas filling systems, which contain both IG assembly and chamber filling stations, require less labor and minimal floor space than offline systems.

Manufacturers producing more than 500 IG units per shift will find that inline systems offer them better production and labor efficiency than offline systems.

For instance, Bystronic Inc. offers a system where gas filling is performed inside the press, while the unit is being assembled. 

“The employed method provides high fill rates, generally between 95 and 99 percent, with only minimal overfill, or lost gas, with argon fill typically only at 50-60 percent and krypton as little as 20 percent overfill,” says Marcel Bally, sales and marketing director for Bystronic. 

Besten Equipment also offers Quik-Dose Level II–a fully automated inline system that, according to Meyer, allows for a leaner manufacturing process than offline systems with very little overfill.

“Quik-Dose senses and utilizes the size and area of the unit being filled and any instructions given by the operator, such as whether or not it contains a grid as it passes through all points of production–allowing uninterrupted manufacturing,” says Meyer.

“Another great benefit is that Quik-Dose memorizes the IG units piece-by-piece and can accurately fill various IG sizes without being reprogrammed.”

However, inline systems are generally more expensive than separate station or batch fill units with a price tag between $100,000 and $200,000, depending on the features needed. 

Offline Gas Filling: Offline gas fill systems, also known as station or batch systems, are considerably more economical than inline systems. Prices range from $2,000 for a shop-built unit for modest requirements, up to $20,000 to $100,000 for semi-automated systems. Offline systems usually are not recommended for manufacturers with an output of 500 units or more, because of the additional handling that is required.

“Where inline systems require one or two operators, a typical offline system would take at least three to accommodate the loading and unloading of units,” says Meyer.

Space is also a factor when considering an offline system. While an inline system requires minimal floor space, a station unit can take up to 250-400 square feet because of the need for movement and staging of IG units waiting to be processed.

Choose Wisely 
Whether an IG manufacturer chooses an inline or offline gas filling system, the bottom line is that gas retention is dependent upon the materials that are used. When used in conjunction with a warm-edge spacer system, gas retention is vastly improved throughout the life of the IG unit. 

“The materials used and the quality of the design and workmanship influence the effectiveness of the gas barriers,” says Bally. “If the spacer system includes a solid depth of continuous butyl-based material, gas losses should be less than .01 percent per year.”

With the low cost of argon, advanced technology, minimal manpower and floor space, gas filling remains to be one of the greatest values in increasing thermal performance of IG units. Manufacturers should view this as an opportunity to not only improve the products that they take to market, but also an opportunity to advance their marketing power to the increasingly energy-conscious homeowner. 

Kevin Zuege is the director of technical services for TruSeal Technologies Inc. based in Beachwood, Ohio. 

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