Fire Rated Glazing
There are many different types of fire rated glazing, using many different technologies to protect against the effects of fire. However, all fire rated glazing falls into three basic categories. Fire Protective, Fire Resistive, and Heat Reflective glazing.
Fire Protective Glazing Products
Fire Protective Glazing can be used for applications up to 45 minutes and contains smoke and fire, not radiant heat.
Normal glass will break under heat stress during a fire, allowing dangerous smoke to travel to surrounding areas. Fire protective glazing contains dangerous smoke and flame by maintaining its integrity during a fire. If the application is more than 25% of the wall area, fire protective glazing cannot be used. Fire protective glazing is allowed in applications over 45 minutes for doors only and is limited to 100 sq.in. in this case.
Fire Resistive Glazing Products
Fire Resistive Glazing can be used for applications over 45 minutes and contains all effects of fire.
Fire resistive glazing contains smoke and flame during a fire as well but also blocks radiant heat. Radiant heat can easily ignite materials on the non fire side of normal glass and cause serious injury to people exiting a building. Only fire resistive glazing, such as SuperLite II-XL, protects people and property from the effects of radiant heat and can be thought of having the protection of a transparent wall.
Heat Reflective Products
Heat Reflective can be used for applications up to 60 minutes and reflects radiant heat back to the fire, providing partial protection.
Most buildings in fire prone areas use fire resistant materials on the roof and walls, but overlook the most important danger – radiant heat. Heat radiating from the fire through conventional windows will set curtains and other flammable objects on fire inside the building or home within minutes.
Heat reflective glazing, such as SuperLite I-XL, is a specialty tempered glass that reflects radiant heat like a mirror, protecting people and property on the non fire side. SuperLite I-XL does not pass the hose stream test and requires AHJ approval. Most AHJs recognize that the hose stream test was designed for structural building integrity and not as a thermal stress test for fire-rated glazing. Sprinkler activation does not compromise the performance of SuperLite I-XL.
Tempered glazing products provide the best protection and durability. While non tempered products may meet impact safety standards by applying a film, they may still crack and need to be replaced after impact.
In 1977, A federal safety standard – Consumer Product Safety Commission 16 CFR 1201 – was established to protect people from injuries due to accidental impact with glazing. CPSC 16 CFR 1201 is required for all door and sidelite applications and is recommended for any application where human impact is a concern. SuperLite I, SuperLite I-XL, and SuperLite II-XL glazing uses tempered glass and is the best choice for areas where impact is a concern.
The Hose Stream Test
The hose stream test was developed to measure the structural integrity of a fire assembly – not the thermal stress performance of glazing materials.
In the late 1890s, cast and wrought iron were commonly used in construction. Unlike steel, they failed in a brittle manner when heated in a fire, creating a risk for firefighters. As a result, the hose stream was created to test the integrity of these support members. Currently, there is some debate as to how the hose stream test is applied to glazing systems.
FACT: The hose stream test is not required for fire-rated constructions of less than one hour. NFPA 251, Standard Methods of Fire Tests of Building Constructions and Materials, specifically makes an exception for constructions rated less than one hour.
Fire fighters along with code officials have stated their favor of a product like SuperLite I-XL, which does not pass hose stream, because it is quick and safe to remove in the event of a fire, allowing for access, smoke release and safe egress of occupants.
“In my opinion the hose stream test is inappropriate for all glazing installations. It may be appropriate for glazing in exterior walls where the protections of openings is required because the development of through openings, i.e. breaking of glass, could permit flame travel. But, inside a building where the glazing may be in a corridor wall, the hose stream (as spelled out in the test standard) is not realistic.” – John G. Degenkolb Fire Protection Engineer, Code Consultant
Consult the local Authority Having Jurisdiction (AHJ) to confirm whether the hose stream requirement is valid for your application.
Thermal shock occurs when glass is rapidly cooled and areas of the glass are exposed to contrasting temperatures. The expansion and contraction of the glass causes stress and will shatter the glass if it is not designed to withstand thermal shock. All SAFTI FIRST glazing withstands thermal shock.
These methods of fire tests are applicable to swinging door assemblies, including door frames with lights and panels, of various materials and types of construction for use in wall openings to retard the passage of fire.
Positive Pressure Fire Tests of Door Assemblies: UL 10C
The method does not provide an evaluation of a swinging door assembly when that assembly is part of a larger assembly (e.g. sliding fire door assembly), or when it is intended to be used as an elevator entrance.
Tests made in conformity with these test methods are intended to register performance during the test exposure; but such tests shall not be construed as determining suitability for use after exposure to fire.
It is the intent that tests made in conformity with these test methods allow for the development of data to enable regulatory bodies to determine the suitability of door assemblies for use in locations where fire resistance of a specified duration is required.
These methods are intended to evaluate the ability of a door assembly to remain in an opening during a predetermined test exposure.
The tests expose a specimen to a standard fire exposure controlled to achieve specified temperatures throughout a specified time period, followed by the application of a specified standard fire hose stream. The exposure, however, is not representative of all fire conditions, which vary with changes in the amount, nature, and distribution of fire loading, ventilation, compartment size and configuration, and heat sink characteristics of the compartment. It does, however, provide a relative measure of fire performance of door assemblies under these specified fire exposure conditions.
Any variation from the construction or conditions that are tested is capable of substantially changing the performance characteristics of the assembly.
The methods do not provide the following:
- Full information as to performance of all door assemblies in walls constructed of materials other than those tested.
- Evaluation of the degree by which the door assembly contributes to the risk of fire by generation of smoke, toxic gases, or other products of combustion.
- A temperature limit on the unexposed side of the door assembly.
- A limit on the number of openings allowed in glazed areas or of the number and size of lateral openings between the door and frame.
- Measurement of the degree of control or limitation of the passage of smoke or products of combustion through the door assembly. Note: See limitations for the passage of smoke detailed in the Recommended Practice for the Installation of Smoke-Control Door Assemblies, NFPA 105.
A product that contains features, characteristics, components, materials, or systems new or different from those covered by the requirements in this standard, and that involves a risk of fire or of electric shock or injury to persons shall be evaluated using appropriate additional component and end-product requirements to maintain the level of safety as originally anticipated by the intent of this standard.
A product whose features, characteristics, components, materials, or systems conflict with specific requirements or provisions of this standard does not comply with this standard. Revision of requirements shall be proposed and adopted in conformance with the methods employed for development, revision, and implementation of this standard.