To know if glass is fire safe, look for specific markings or labels on the glass itself or its frame that indicate it has been tested and certified to meet fire resistance standards by recognized testing laboratories.
Fire-rated glass is specially manufactured and tested to withstand high temperatures and prevent the spread of fire and smoke for a specified period. Standard glass is not fire-safe and will typically break quickly when exposed to the heat of a fire. The key to identifying fire-safe glass is understanding the certifications and markings it carries.
Identifying Fire-Rated Glass Markings
Reputable fire-rated glass products will have permanent markings etched into the glass or labels applied by the manufacturer or testing agency. These markings indicate the level of fire resistance and the standards the product has been tested against.
According to the provided reference:
- "Standard oh" indicates that a product has been tested to UL 9 or NFPA 257. These standards relate to fire tests of window assemblies and door assemblies, often for fire protected openings with hose stream testing.
- "d" identifies a product that has been tested to NFPA 252 or UL 10c. These standards are for fire tests of door assemblies, including positive pressure tests, and also involve hose stream testing.
These markings signify that the glass (or the assembly it's part of) has passed rigorous fire resistance tests conducted by organizations like Underwriters Laboratories (UL) or tested according to standards developed by the National Fire Protection Association (NFPA).
Common Markings and Standards
Beyond the specific examples from the reference, other markings and standards you might see include:
- Hour Ratings: Often, the marking will include a duration (e.g., 20 minutes, 45 minutes, 60 minutes, 90 minutes, 120 minutes). This indicates how long the glass is certified to resist fire under test conditions.
- "W" or "Hose Stream": Signifies the product passed the hose stream test, which assesses its ability to withstand the impact and cooling effect of water from a fire hose after being exposed to fire. The "oh" and "d" markings mentioned in the reference imply this testing.
- Certification Marks: Look for logos or names of testing laboratories like UL (Underwriters Laboratories), Intertek (Warnock Hersey), or FM Approvals. These marks confirm the product has been certified by a third party.
- Classification: Markings may also indicate whether the glass is fire-protection rated (primarily compartmentalizing fire and smoke, often without significant radiant heat blockage) or fire-resistive rated (blocking radiant heat transfer and offering higher overall performance).
Where to Find the Markings
Check the corners or edges of the glass pane itself. Markings are typically etched into the glass surface and may be small. If the glass is part of a door or window assembly, check the frame or any attached labels.
In summary:
To determine if glass is fire safe, look for etched markings or labels that reference testing standards like UL 9, NFPA 257, NFPA 252, or UL 10c, often accompanied by a time rating (e.g., 45 min) and a certification mark from a recognized laboratory. The presence of markings like "oh" or "d" specifically indicates testing to the standards mentioned in the reference.
