Kristin Bigda

Fire-protection rating and Fire-resistance rating, not the same thing.

Blog Post created by Kristin Bigda Employee on Jun 19, 2015

The terms "fire protection rated/rating" and "fire resistance rated/rating" are used throughout NFPA codes and standards and are often used interchangeable in discussion and in writing.  However, these two terms are exactly that two different terms, with two different meanings, and two different applications.  It is important to understand the difference in the two to be able to use them properly and gain a better understanding of Code requirements where fire protection ratings or fire resistance ratings may be required.

 

Fire Protection Rating. The designation indicating the duration of the fire test exposure to which a fire door assembly or fire window assembly was exposed and for which it met all the acceptance criteria as determined in accordance with NFPA 252, Standard Methods of Fire Tests of Door Assemblies, or NFPA 257, Standard on Fire Test for Window and Glass Block Assemblies, respectively.

 

Fire Resistance Rating. The time, in minutes or hours, that materials or assemblies have withstood a fire exposure as determined by the tests, or methods based on tests, prescribed by this Code.

 

  Fire barriers have fire resistance ratings, and opening protectives, such as fire doors or fire windows, have fire protection ratings. Where a product, such as a glazing material, has been tested to the appropriate test standards, and passed the necessary test criteria, it can be given a fire resistance rating and may be used in the same installations as a fire barrier or assembly requiring a fire resistance rating.

  The test procedures on which the ratings are based, that is, NFPA 251/ASTM E 119/ANSI/UL 263 for fire barriers and NFPA 252/ANSI/UL 10B/ANSI/UL 10C for fire doors, are different.  The acceptance criteria for fire protection–rated assemblies, such as fire doors, differ from those for fire resistance–rated construction, such as a wall or floor/ceiling assembly. The limitation of temperature rise through the fire door is not normally a measure of acceptance, although it is a measure of acceptance for a fire resistance–rated assembly such as a wall. In addition, during the course of the fire test, fire doors will expand on the exposed side and, as a result, will warp — sometimes expanding through the door opening at the top of the door. This expansion and warping can result in some flaming through the top of the door openings. The test standards recognize this phenomenon, and a certain amount of such flaming is permitted under the acceptance criteria. This does not adversely affect safety, given that fire protection–rated assemblies are intended to protect relatively small openings in larger fire resistance–rated barriers. 

 

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