Volume 39, Issue 7,
Preventing IG Failures
IGMA’s Educational Seminar Dissects a Hot Topic
by Alan B. Goldberg
Preventing insulating glass (IG) failures is a topic of constant concern for many. To educate the industry, the Insulating Glass Manufacturers Alliance (IGMA) conducted an educational seminar on preventing IG failures, May 3-4, 2004 at the Woodfield Hyatt in Schaumburg, Ill. Bill Lingnell, IGMA technical director, opened the meeting by speaking about the need to raise the bar on quality. The presentations by component manufacturers were aimed at doing just that.
In a brief overview, Randi Ernst, of FDR Design, emphasized the need for better training. “We can’t expect (component) manufacturers to carry the burden of training,” he said.
According to Ernst, since the consolidation of the Sealed Insulating Glass Manufacturers Association and Insulating Glass Manufacturers Association of Canada to form IGMA in October 2000, one of the organization’s goals has been to work toward the certification of 50 percent of the glass fabricators in North America to its standards for producing units (this is a voluntary certification program).
Chris Barry, director of technical service for Pilkington, discussed four types of glass breakage—tensile, impact, overload, weakness in glass—and showed examples of each. He said a slight impact to a corner while moving on a conveyor is enough to create a weakness in the glass; and with a significant change in temperature, a tiny crack can lead to breakage.
Glass Washing and Cutting
Recommendations for glass washing and cutting were presented by Mike Burk, productivity solutions manager for Glass Equipment Development. He advised manufacturers to get all suppliers involved with recommendations for the proper use of equipment and materials.
He suggested the use of water-soluble cutting oils so they can be washed away, and urged the replacement of cutting wheels on a regular basis to avoid damage.
“The tendency is to use more pressure instead of replacement. Check for accurate cuts, dimensions and squareness or glass damage.”
Jeff Haberer, who works in product development at Cardinal IG, discussed coated glass—types, handling, storage, cutting, washing and fabrication. He described sputtered versus pyrolytic glass, reflective and low-E, as well as tests for identifying reflective and low-E glass. (For more on glass handling, see related story in the October 2003 USGlass, page 56.)
The role of desiccants in IG units was outlined by Tom Dangieri, senior application specialist at UOP Molecular Sieves. Defining desiccants as a material with a high affinity for moisture, he explained their ability to remove moisture and solvent vapor after the unit is assembled. Dangieri covered many do’s and don’ts in handling, emphasizing the need to inspect for damage when the desiccant is received and to avoid using a desiccant that has been damaged in transit or storage. He stressed the importance of selecting a desiccant based on a priority of needs—water capacity, solvent capacity, air and inert gas—and described the two key types of desiccant used in the industry: molecular sieve and silica gel.
Denny Raske, director of international sales at Allmetal Inc., gave an overview of spacers and muntin systems. He explained the primary functions of spacers—to separate lites of glass, hold or carry desiccant, provide aesthetic value—and described the features of each type, including shape, height, substrate and finishes and colors. He also covered do’s and don’t s.
“Don’t allow burrs or high spots in the spacer, especially in corners or bent spacers. Don’t use spacers with residual cutting oils or plugged breather holes,” he said.
Muntin bars, which are used to simulate divided lite windows and for security, are available as flat, contour, extruded or pencil bars, in a variety of finishes. He told the audience to be sure to wear gloves to avoid contamination, and to minimize contact with the sealant and align muntin bars properly with the reference grid.
Why units are gas-filled, why argon gas is preferred, the mechanics of gas filling and how it works were explained and demonstrated by FDR’s Ernst. He said it was the introduction of low-E coated glass and plastic film that made gas filling viable.
“Gas filling is a low-cost procedure that provides major improvement in the product’s thermal performance. Argon is the gas most frequently used because it is inexpensive and readily available.”
He pointed out that krypton, while more expensive, is impressive in glazing units where small thickness is of prime importance. Although energy savings are important, he said the real comfort benefit of gas filling is the increase in the inner glazing temperature, which substantially reduces, or can even eliminate, condensation on the glass.
Kristen Gray, sales manager in the window business unit at H.B. Fuller Co., described the function of the sealant, generic types of sealants used in insulating glass units, physical properties, quality control issues and the performance of IG units. She explained the difference between single-seal and dual-seal type units, and compared generic types of sealants based on ultraviolet resistance, heat resistance, cold-impact resistance, cohesive strength and solvent/plasticizer resistance.
“Defective glazing will cause premature failure of IG units,” said Werner Lichtenberger, special projects manager at TruSeal Technologies, who reviewed glazing techniques. Glazing should be done at temperatures above 40 degrees F. Below this temperature, frost and condensation can contaminate the substrate. Surface preparation, or a clean surface, is necessary prior to glazing. Setting blocks should be neoprene or EPDM with a Shore A hardness of 80-90 durometer. Handle units carefully, he said, to avoid edge damage and possible stress cracks. Glazing tapes must be kept under proper compression, and vent to the exterior. The size, shape and position of the vent (weep) holes is critical.
The next IGMA gathering will be its summer technical conference, which will take place August 5-8 at the Harbour Towers Hotel & Suites in Victoria, British Columbia.
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