To earn a fire protection rating, glazing must pass the testing standards referenced in the applicable building code.
There are several types of tests. Sometimes passing all of them is required, sometimes the product only needs to pass a few of them.
These tests conducted by independent testing facilities, such as Underwriters Laboratories. Passing these tests allows the manufacturer to permanent label the glass with a certification from the testing lab. This helps building inspectors and building owners have confidence that the correct product was installed in the building.
Some of the test standards include: ASTM E-119, ASTM E2074, ASTM E2010, UL 263, UL 9, UL 10B, UL 10C, CSFM 43.7, NFPA 80, NFPA 251, NFPA 252, NFPA 257, UBC 43.2, UBC 43.4, UBC 7-2, UBC 7-4, CAN4 S-104, CAN4 S-106.
In general, for fire testing, the glass and framing are placed in a furnace and burned. The temperature inside the furnace is controlled following a standard time-temperature curve specified the test standard. At five minutes, the temperature in the furnace reaches 1,000° F (583° C). At 30 minutes it rises to 1,550° F (843° C). After one-and-a-half hours it approaches 1,800° F (980° C).
For a given fire rating, the glass and framing must meet several performance criteria specified the test standard at the conclusion of the fire test. These include:
“The window assembly shall remain in the wall in which it is installed for the duration of the fire test”
“No flaming shall occur on the unexposed surface of the assembly”
“There shall be no separation of the glazing material edges from the glazing frame”
“There shall be no openings in the window assembly”
Additional performance criteria address limitations on the movement of operable components from their closed positions and limitations on the movement of the overall assembly relative to the wall.
Hose Stream Test
Most fire tests in North America include a hose stream test at the conclusion of the fire test. Within two minutes of completion of the fire test, the hot glass and framing is subjected to a hose stream test. The side of the assembly exposed to the heat of the furnace is sprayed with water from a fire hose at pressures and durations specified in the test standard.
The purpose of this test is to provide “a method for evaluating the integrity of constructions and assemblies and for eliminating inadequate materials or constructions.” (NFPA 257, B.11.4) The standards further state “the cooling, impact, and erosion effects of the hose stream provide important tests of the integrity of the specimen being evaluated.”
To successfully pass the hose stream test, the glass and framing must remain intact and not separate from the frame, within limits specified of the test standard.
Most fire-rated glass is located in areas subject to human traffic and hence are required, under the relevant building code, to provide some measure of impact-safety.
The test standards used to assess impact safety include ANSI Z97.1 and CPSC 16CFR1201.
The test generally involves smashing a series of large panels of glass with a heavy impactor to see if and how they break. In general laminated glass that passes the test essentially prevents the impactor from passing through the glass. Tempered glass on the other hand can be broken and allows the impactor to pass through, but the shards of broken glass are required to be small. In this sense different materials can pass the impact-safety test with different strategies. The goal is to prove that the glass is safe and wont cause significant ‘cutting and piercing’ injuries when impacted. This is not to say that a human can penetrate the glass and fall through it. This means that laminated glass should be used where retention is an issue, such as on mezzanines.
Fire-rated glass can also be tested against additional test standards such as security standards from UL 752 or NIJ 0108.01 or EN 1063.
These standards generally involve launching a series of projectiles at the glass or otherwise attacking it mechanically. These test standards have a range of difficulties (eg. UL 752 level 1 is easier to meet than level 8).
Combining The Testing
Should the application require more than one of these tests standards be met, it is important that all standards are met by the same configuration.
In other words it is critical that the final product passes the original fire test. One cannot simple glue additional layers to fire-rated glass without retesting for fire. The process of adding new materials to a construction may cause it to fail one of the other tests. This is particular true for fire tests. Adding additional layers of plastic or polycarbonate generally will increase the flammability of the product and would likely cause it to fail a fire test. You must ensure that the finished product passes all the tests needed.