What are my choices in fire-rated glazing?

The glass product most often associated with fire rating is wired glass. It has been around more than 100 years. In North America, wired glass was typically rated for 45 minutes in lite sizes up to 9 square feet (1,296 square inches).

However, in the new CGSB standard CGSB 12.1 2017 wire glass is not considered a safety glazing material under this new standard. Wire glass can only be used in punched opening above 42 inches and greater than 24 inches from a door. As per NFPA 80 all wire glass shall be permanently labeled as such and be visible after installation.

A second type of fire-rated glazing is Glass Ceramics such as KeraLite®. KeraLite® is a wireless product looks similar to regular window glass, which provides greater design flexibility. The KeraLite®, provide fire ratings from 20 minutes to 3 hours, and come in sizes up to 30.46 square feet per lite. KeraLite® Glass Ceramic is able to withstand the thermal shock of water from sprinklers or fire hoses. Where impact safety is required, they are available with up to Category II CGSB 12.1 2017, CPSC 16CFR 1201, impact-safety ratings.

KeraLite® is also available in insulated glass units (IGU's). The IGU's are made of two layers one of which is KeraLite® as the interior lite with an air space in between. They can incorporate many types of float glass / tempered glass, including clear, hard coat low emissivity (low E) . Depending on which components are used, they can provide fire protection and comply with energy codes. IGU's are sometimes used for interior applications where sound reduction is desired.

Another category is ContraFlam® which is a multi-layer assembly that is a fire-resistant tempered safety glass comprised of multiple layers with insulating intumescent layers, ContraFlam® is tested to the same fire-resistance standards as solid walls, and are not restricted to 25 percent of the wall, as may be the case with Glass Ceramics. This flexibility makes products like ContraFlam® suitable for use in floor-to-ceiling and wall-to-wall designs, or in full lite glass doors. These large expanses of glass have obtained fire ratings up to 2 hours. They are typically used where architects desire (or building codes require) the blockage of heat transfer through the glass. Designers can thus provide clear, fire-rated glass walls that allow visibility, light and security. Like glass ceramic, ContraFlam® is available with up to Category II CGSB 12.1 2017, CPSC 16CFR 1201 impact-safety ratings.

Last but not least is specially tempered glass products. Products such as Pyroswiss®, Pyroswiss was first tested in 1981, it quickly becoming the original, clear, specially tempered, and impact safety glass for 20-minute fire-rated doors. It is important to note these products cannot withstand thermal shock, and are therefore are unable to pass the ‘hose stream test’ which is required in Canada. As a result, applications for these products are generally limited to use in 20-minute fire doors. (USA)

What is the difference between fire-protective and fire-resistive glazing systems?

Fire Protective (otherwise known as Fire-Rated Glass Ceramics) means the glazing protects against the spread of flames and smoke. Such as KeraLite®. KeraLite® is typically used where building codes allow opening protective assemblies. While such glazing is available with fire ratings ranging from 20 to 180 minutes. This type of glazing must pass the hose stream test.

Fire-Resistive glass provides the same defense against flames and smoke as fire-protective glazing, and adds further protection by blocking the transfer of radiant and conductive heat energy. Fire-Resistive glass comprise of multiple layers of tempered safety glass with insulating intumescent interlayers. They are typically suitable where building codes require an assembly designated to enclose a space. Examples of such would be wall applications requiring a 60-minute or greater fire rating that must meet temperature-rise criteria, such as stairwells, exit access corridors, or other fire barriers dividing interior construction. This type of glazing must also pass the hose stream test.

Why do I have to have a permanent fire label?

Fire-Rated and Fire-Resistive glazing is available with a wide variety of performance characteristics, specifying an appropriate one for a given application is critical for life and property safety. To help ensure the proper use of glass for various fire-rated applications, a multi-faceted product labeling system was implemented in the 2012 IBC see Table 716.3. As well as in the latest version of CGSB 21.1 2017.

The fire-rated glass marking system includes a range of information, including the product name, basic characteristics (e.g., tempered, laminated, etc.), compliance with impact safety requirements, and listing information for the applicable independent testing agency, such as Underwriters Laboratories. R25896

Why is the hose stream test required / test important? (thermal shock)

The fire hose stream test shows how hot glass and surrounding frame assemblies will react when doused by water from a fire hose or sprinkler. Most glass products are unable to withstand the thermal shock of water on hot glass. If nearby sprinklers are activated during a fire, the heated glass may shatter and vacate the frame, thus allowing the spread of flames and smoke.

NFPA 257 states, The hose stream test provides a method for evaluating the integrity of constructions and assemblies and for eliminating inadequate materials or constructions. The cooling, impact, and erosion effects of the hose stream provide tests of the integrity of the specimen being evaluated. The hose stream test is required in Canada and the USA for glass with fire ratings of greater than 20 minutes. In Canada, all fire-rated glazing must pass the test.



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