Fire rated glass speaks to what is fire rated glass and why fire rated glass.
It is used for fire doors, fire windows and fire resistant rated walls, must maintain its integrity as a barrier to the passage of smoke and flames even after it has been exposed to heat for a period of time. Some tempered or laminated glass products can achieve test ratings of up to 20 minutes of fire resistance.
Wired glass is produced by rolling a mesh of small wires into a sheet of hot glass. Hen wired glass breaks from thermal stress, the wires hold the sheets of glass in place so that the glass continues to act as a fire barrier. It carries a fire resistant rating of 45 minutes.
Optical quality ceramic is more stable against thermal breakage than any type of glass. It looks and feels like glass and can achieve fire resistance ratings changing from 20 minutes to 3 hours.
Two other fire rated glass types are fire retardant filled double glazing and intumescent interlayer laminated glazing.
Fire retardant filled double glazing consists of a clear, heat absorbing polymer gel contained between two sheets of tempered glass.
Intumescent Interlayer laminated glazing is made of thin layers of transparent intumescent material sandwiched between multiple layers of annealed glass.
When either glass type is heated by fire, the gel or intumescent interlayers react to form opaque, insulating layers. As a result these products not only resist the passage of flame and smoke, but they also limit the rise in surface temperature of the glass on the side opposite the fire and prevent the transfer of radiant heat through the glass.
These added protective properties make these glass types suitable for use in larger sizes and in a broader range of applications than other types of fire rated product. Fire resistant ratings up to 2 hours can be achieved.
According to the International Building Code this glass must meet the fire endurance requirements of one of three regulations, NFPA 252, NFPA 257 or ASTM E119, depending on whether the glass is part of a fire door, fire window or fire rated wall assembly.
Fire rated glass tested for use in doors and windows is limited in the maximum size of individual lights permitted. However, glass products that can pass more stringent requirements of ASTM E119 for wall assemblies, including fire retardant filled double glazing and intumescent interlayer laminated glazing, have no such size limits and can be used as full substitutes for fire resistant rated wall construction. Also those that are suitable only for use in fire doors and windows, the terms glass fire walls or fire resistive glazing may be applied to the former and fire protective glazing to the latter.
Due to its frequent use in doors and other hazardous locations, fire rated glass must often meet the impact resistance and breakage safety requirements of safety glazing. To meet these requirements, optical quality ceramic is either laminated or film faced to protect it from shattering dangerously when used in such locations.
Ordinary annealed wire glass does not meet safety glazing requirements. While historically its use was permitted in fire doors and windows to a lack of suitable alternatives, this is no longer the case. Where wired glass is now used in hazardous locations, it is also film faced or laminated.
Fire retardant filled glazing and intumescent laminated glazing are both capable of meeting safety glazing requirements.