AAMA/IGMA Summer Conference Day 2: Report from the technical committees
By Patrick Flannery
Jeff Haberer from Trulite and Paul Bush from Vitro chaired a joint meeting of the Insulating Glass Manufacturers Alliance Technical Services Committee and the American Architectural Manufacturers Association Glass Council at their Summer Conference in Victoria. The room of over 50 delegates heard about progress on PIB migration, expansion of structural standards to address jumbo and thin glass, acoustical ratings, vacuum insulating glass guidelines and more. Bush noted that the IGMA’s technical task forces have often done most of the heavy lifting to research and write AAMA standards for some time.
The task group on IGU edge pressure reported on efforts to establish the allowable pressure applied to IGU edges in assemblies, especially with regard to pressure plates, in light of modern seal and glass technology. Haberer commented that that the existing standard of four to 10 pounds per lineal edge was probably written to address annealed glass and only considered the risk of breakage. That standard has come into conflict with installers’ desire to get enough pressure on the gasket to prevent water ingress. IGMA executive director Margaret Webb said that the research needed to generate a new standard was likely too ambitious for a volunteer group and was exploring partnerships with Canadian and American university engineering departments to do the necessary science.
David Cooper of Guardian reported he is forming a task group to incorporate guidelines for vacuum insulating glass into the IGMA glazing guidelines. Guardian’s research suggest VIG will perform differently from normal IGUs when glazed in and when impacted in the field, and these effects may need to be researched in order to guide installers.
Dan Haglin of FDR Design reported that the task group on cavity pressure relief has almost completed its document. The product will discuss the pros and cons of various methods of allowing IGU to adjust to atmospheric pressure changes when units are moved from one elevation to another. Capilliary tubes, breather tubes, valves, dessicant, bladders and inflating/deflating the units will be among the strategies addressed.
Brian White of H.B. Fuller reported on research by the PIB compatibility task group, which used a test designed by IFT Rosenheim to see the impact of different sealants on the rigidity and viscosity of PIB under different temperature and pressure conditions. Popular silicones from various manufacturers were tested against common PIB 29. Sure enough, sealants listed as compatible showed no effect on the PIB, but incompatible sealants caused significant softening and decreases in viscosity under cone and rheology tests. One surprising result was that the drop in viscosity seemed to have an inverse relationship to temperature – the PIB was runnier at room temperature than at higher temperatures. One theory is that higher temperatures cause the volatile chemicals in the silicone to offgas rather than penetrate the PIB and soften it, but that’s not proven at this time.
IGMA techncial consultant Bill Lingnell reported on work to update the ASTM E1300 structural standard. The load resistance charts are being updated and the group is looking at including an allowable stress standard for ceramic enamel frit. An appendix is being added to address edge pullout due to glass deflection. This has become an important problem with jumbo and thin glass assemblies. Work also continues on adding a thermal stress standard.
There were a number of other updates from other organizations on the technical work they are doing, but these were the highlights.