Thursday, August 28, 2014

Fire Protection... With Fire Resistant Assemblies

There are three components to fire protection: active fire protection, passive fire protection, and fire prevention.  Fire prevention consists of education efforts such as decreasing the number of ignition sources, while active fire protection consists of detection and suppression, such as automatic sprinkler systems, and passive fire protection – the focus of this post - is concerned with preventing or slowing the spread of a fire. Passive fire protection is measured with the use of a Fire Resistance rating.

Passive fire protection includes compartmentalizing the building by using fire-resistance rated (or fire – rated) walls, roofs and floors. By creating smaller compartments, such as rooms or floors, you can prevent or slow the spread of fire from one area to the next.  This compartmentalization allows individuals more time to escape, which illustrates the definition of a Fire Resistance Rating: simply put - the time, in hours, that a material or construction can withstand fire exposure. The higher the rating, the more time the occupants have to safely evacuate the structure. This is such an important factor that modifying a tested and rated assembly is not to be undertaken without consulting the proper personnel. It often requires further testing to ensure the established rating will be met by the modified assembly.
verticalfirefurnaceIn the United States, a representative sample of the assembly is sent to an accredited (for more information on accredited labs, read What Does It Mean for a Testing Agency to Be Accredited) lab. Using accepted standards such as ASTM E119 or ANSI/UL 263, the lab exposes the sample to a fire for a specified amount of time, such as one, two, or three hours. After exposure, a hose stream (similar to a fire truck hose) blasts the assembly. An assembly that remains in – place or maintains its load after the hose stream has been applied achieves a fire-rating. The rating applies to the assembly as a whole, not the individual components. This is why modifying fire resistant assemblies is not such an easy task. If you change any one of the components, or the layout, the rating can decrease.
A good place to start asking about modifying your fire rated assembly is your testing or certification agency.  They can consult the technical documents such as the testing or listing report that detail the assembly as tested and can provide guidance on what modifications are acceptable without retesting. If you need modifications beyond what is listed or recommended, you may require additional testing to establish a fire resistance rating. The decision to accept a modification is still dependent on the authority having jurisdiction.
Whether your product will be used in manufacturing, motor vehicles, RV’s or housing, NTA can provide the fire testing you need.Contact us today to learn more.

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