The purpose of a spacer bar
A spacer bar is used to separate the panes of glass forming a cavity width that offers thermal insulation. The spacer bar also holds the desiccant, and the small holes in its surface allow the desiccant to adsorb water vapour from within the sealed cavity.
Spacer bars are constructed into a frame that is smaller than the glass to allow the sealant to be applied flush to the edge of the glass. Spacer bars can be cut to size using saws and then connected using corner keys that are inserted into the tube endings and cannot be seen.
Warm edge spacer tube
Warm edge is so called as it insulates the edge of the sealed unit where most heat is lost. Often referred to as a ‘thermal break’, it slows the heat loss across the edge seal/spacer matrix and therefore improves insulation. Warm edge lowers the U-values of windows and is beginning to be specified as standard for many applications because of this improved insulation.
Aluminium spacer tube
Aluminium has been used ever since double glazing became popular. This is because it is lightweight, structurally strong and being one of the most abundant metals on earth, it is very cheap. It is also one of the worst products to use as aluminium is a highly conductive metal and conducts heat at the edge of the sealed unit, reducing the insulation effect of double glazing.
Steel spacer is used in fire rated glazing as it has a better heat resistant function, keeping the glazing stable.