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