Volume 12, Issue 7 - September 2011

Protect the View

Check Your Gas
Are You Sure It’s in There?
by Mike Burk

The above seems to be a simple, legitimate question to ask when discussing the insulating glass (IG) gas-filling process. I often query production managers and associates with the familiar refrain, “Are you sure it’s in there?” I would expect a quick “yes” and a brief explanation of the company’s quality control program or perhaps the process testing procedures. Instead, I often receive a blank stare as if I crossed some personal boundary or was seeking information about some deep hidden company secret. Even if you don‘t want to share your process information with anyone outside your company, you must ask yourself, “Am I sure it’s in there?”

In the July 2005 issue of DWM, this column was titled “Argon—Yeah, It’s in There” In that column I explained that it was no longer acceptable simply to tell the consumer that the window or IG unit contains argon.

Many things have changed in six years. More window manufacturers are offering gas-filled units that contain argon, krypton or a combination of both. Xenon has been discussed as the next step. There are improved procedures and equipment for determining the gas percentage. Codes and standards have been updated. In some cases a manufacturer’s gas filling process must be certified by a third-party certification organization.

But some things have not changed. In some facilities untrained or poorly trained production workers still are producing gas-filled units. Often the final gas content is not measured and the filling equipment is not maintained properly or calibrated on a regular basis. The gas fill hole is poorly sealed sometimes, as management pushes for faster filling and increased production.

Today there are quick accurate methods of determining the gas fill percentages of insulating glass. It is critical to review your company’s gas-filling process. Consider the following areas for investigation.

"Most quality programs, certification organizations or third-party inspectors require regular sampling of gas-filled production units per shift."

It is important that the personnel operating and maintaining gas-filling equipment understand the gas-filling process. Instruct the operators about how inert gas improves the thermal performance of IG units, only if the units are filled and sealed properly. Test the associate’s knowledge to be sure that he understands the operation of the gas-filling equipment. Make sure the maintenance group is knowledgeable about the equipment calibration procedures. Confirm that the calibrations are completed as required.

Manual filling methods usually include one or two lances inserted through holes in the spacer system. The air in the unit is vacuumed out as the gas enters the air space. Some gas-filling equipment detects and alerts the operator when the gas in the unit is at the specified percentage. Other equipment utilizes timers. The fill time is calculated based on the volume of the air space. Operators must be instructed on equipment operation, correct filling speeds and fill times to assure proper fill percentages. The filling lances should be inspected at the start of each shift. They must be repaired or replaced if damaged.

Most automated IG manufacturing equipment with gas-filling capabilities use a chamber fill method to fill the units. A partially completed unit is moved into an enclosed chamber. After the entire chamber is filled with argon, the assembly of the unit is completed, encapsulating the argon. The maintenance group needs to work with the production associates to ensure the equipment is operating consistently and correctly. Preventive maintenance must be completed as scheduled.

Quality Control
Most quality programs, certification organizations or third-party inspectors require regular sampling of gas-filled production units per shift. For example, IGMAC recommends the number of samples to be tested based on the number of units produced. Check your company’s current quality policy or certification body for the required gas filling sampling and documentation.

There are three commonly used methods to determine argon concentration in IG units. These include gas chromatography (GC), oxygen sensors and spark emission spectroscopy (SES). These methods are described in detail in the ASTM Standards E-2269, E-2323 and E2649, respectively.

In addition to making sure the units are filled as specified, associates must be aware of the safety requirements and possible dangers of handling high-pressure cylinders. OSHA Section 1910.101(b) is a good way to understand the in-plant handling, storage and utilization of compressed gases in cylinders. Your compressed gas supplier can assist in specifying safe storage and handling equipment.

There also are special safety concerns for handling liquid argon. Contact with rapidly expanding argon near the point of release may cause frostbite, skin color changes and blistering. Check with your supplier for the safe handling of liquid argon.

Argon often is called “inexpensive” when compared to krypton or xenon, but steps still should be taken to minimize waste. Turn off the supply when the filling system is not in use and check for leaks in the supply system. Make sure operators understand the filling equipment operation in order to minimize waste.

Take the time now to review your gas-filling process, sales literature and gas retention warranty. Know that your sales representatives can respond with an assuring “yes” when asked, “Are you sure it’s in there?” Be confident that your windows will remain energy-efficient as long as they protect the view.

Mike Burk serves as manager of workplace learning and performance for Edgetech I.G.

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