UL Ratings Defined:
"F" Rating -The "F" Rating defines the amount of time before flame pokes through
openings to the unexposed side of the test assembly. Most Contractors are familiar with
the Fire Rating of a wall, floor or door being stated as "1 hour" or "2 hour".
"T" Rating -The "T" Rating defines the amount of time for the surface of the penetrating
item on the non-fire side of the test assembly to rise 250F plus ambient temperature.
"L" Rating -The "L"Rating measures the amount of air that moves through an opening in
cubic feet per minute per square foot of opening area, at ambient temperatures and 400F.
The two temperature levels simulate cold and hot smoke moving in a building. Many
firestop systems have L Ratings of less than one.
"W" Rating - The "W" Rating measures resistance of a firestop product to standing
water in buildings. Developed to address concerns by building owners about the ability of
a firestop system to resist the passage of water through floor assemblies, the W rating
development offers a new quantifiable characteristic for a firestop system. The test
protocol simulates water on a firestop system for 72 hours, under a 3' head of water.
