Toughened, Laminated and toughened laminated fire glass – Confused?

The world of fire glass has been evolving gradually over a number of years. From its origins with the invention of embedded wire fire glass, clear fire resistant glass has developed into a complex, specialised industry today. This complexity of fire glass products can confuse the unsuspecting specifier, builder contractor and installer, sometimes leading to incorrectly installed applications, which is a subject matter in its own right.

This article will concentrate on the fire glasses available to the market today, these briefly consist of: monolithic embedded wire; laminated float glass; modified toughened glass; laminated modified toughened; borosilicate and ceramic. The latter two, although offering high performance, suffer with issues on visual clarity or size limitations and generally are very expensive in comparison to other fire glasses.

This leaves us with embedded monolithic wired, laminated float glass, modified toughened glass, and laminated modified toughened. All these glasses have particular characteristics and attributes which makes them each more suitable for specific applications. For example:

Monolithic embedded wired – this is the original fire resistant glass and still utilised today in budget applications or when required to match existing wired installations. It fulfils a limited function of being easily available at short notice but contains unsightly wire mesh that is no longer required for fire protection with the technically advanced products available on the market today.

Laminated float glass – a good example of this is Pyroguard EW30. This product is a combination of 3mm float glass and a bespoke patented reactive interlayer which bonds the glass layers together providing a stable layer in a fire application.

This product is suitable for integrity only and integrity with radiation control applications into both steel and timber door and framing solutions. The main advantage of this type of product is application flexibility, price and lead time. This is due to its ability to be manufactured as a stock sheet which can be held locally by approved fire glass stock holders and cut to order by hand like a commercially available laminated glass. This effectively means a high performing fire glass off the shelf when and where you need it.
This laminated float glass principle can be expanded to cover glass at higher classification up to 60 minutes full fire insulation through the addition of glass and active intumescent interlayers, again allowing for a product that can be held locally for a fast delivery. This type of product does require the use of specialist cutting equipment.

Modified tough – Once again Pyroguard have products that fall into this category and this takes the form of Pyroguard T EW30/6. These products as the name may suggest, are a 6mm float glass which have been specially processed utilising a special heating and cooling profile which induces the desired stresses within the glass. This enables it to withstand the demands of the fire test and achieve classifications as high as EW60 (radiation control to 60 mins). Being a toughened glass it is also has an incredible strength-to-weight ratio achieving the highest impact classification at 1C1 when tested to the BS EN 12600 pendulum test. Unfortunately due to the nature of this product it has to be manufactured to bespoke sizes and cannot be modified after the toughening process, this therefore leads to slightly longer lead times. This is a very economical solution to the requirements of fire barriers for the budget conscious project where the building regulations allow it.

Laminated modified tough – as the name suggests these products are derived from the modified toughened products but have for various reasons been laminated to give enhancements over and above those of the original product. These derivatives may start with the inclusion of a PVB type interlayer to provide additional security against physical attack for applications in financial institutions, specialist medical centres or detention centres. Alternatively or additionally they can include special reactive intumescent interlayers which can give enhancements such as radiation control up to 120 minutes in products as thin as 13mm.

These types of products can also be constructed as multi layered laminates with the inclusion of multiple cavities of various thicknesses. These types of multi layered products are capable of offering fire resistant classifications from the base E30 up to EI120 at a total product thickness of only 47mm with new developments of EI 180 (full fire heat insulation of 3 hours in a suitable framing system). These new specialist glass types are also continually pushing the boundaries on clear glazed areas offering the clean lines and vast tested areas up to 2845mm x 3120mm satisfying the demands of the architects and designers.

In conclusion, fire glasses can be sourced to fit all types of building applications and different levels of fire resistance. Entry level products are relatively inexpensive for the protection they provide and the complex insulation products, although costly, provide protection from fire to a level unimaginable a few decades ago.

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