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Glazing distortion

Postby xjr328 » Sat Oct 17, 2009 6:16 pm

In Reply:

Rubbish..... firstly hot melt units are assembled on a press bench, using a hot butyl sealant the sealant increases the temperature of the air molecules inside the unit causing the psi inside the unit to increase, using the wrong desicant can cause fumes to become trapped in the unit as well, when the air cools back bown it returns to its original state.

Secondly two part mix units (cold cure) are firstly pre-assembled using a spacer bar with a primary seal the units are then back filled with the sealant (Secondary Seal) the units should then be left to set before moving.

Glass distortion has nothing to do with how it was assembled, there are a few reasons why glass distortion is present in sealed units, the main reason is due to the fact that the unit is sealed... by making a sealed unit with float glass you CAN NOT stop glass distortion the air that is trapped between the two panes of glass will react to temperature change, on a hot day the air molecules vibrate and expand causing the sides of the unit to swell this causes a positive deflection, on the other hand on a cold day the air molocules bacome less active and the units psi reduces causing a vacuum effect. because the glass sides are made of thin glass it will swell or belly in the middle. the only way to stop this effect is pressure equalisation, this allow the unit to draw air in on cold days and expell air on hot days, CCWW UK can pressure equalise your units they install vents into the unit and inject a super-hydrophiliv coating that prevents the moisture in the air passing through the units condensing on the glass.

You can spend the next ten years talking about how to stop glass deflecting and blame sealants, spacer bars, quality of glass and even thickness of glass, the bottom line is untill you stabilse the air pressure inside the unit you will never stop it. as I said earlier there are other reasons but these are quality and manufacturing techniques that can be fine tuned after pressure equalisation has been achieved.
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