Hilti EDucation
What is a W-Rating?
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CFS-S SIL SL Firestop Silicone Sealant
The W-rating refers to a firestop system’s
ability to resist water passage through a floor
assembly. In August of 2004, UL established
a procedure to quantifiably measure a firestop
product’s water resistance in buildings. To
qualify as a Class 1 W-rated system, the
firestop assembly must withstand a 3-ft head
of water for 72 hours with no leakage. This new
optional W-rating for water resistance joins
UL’s other optional measure, the L-rating for air
leakage, and the two required measures, F and
T-ratings.
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CP 606 Flexible Firestop Sealant
•
CP 618 Firestop Putty Stick
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CP 620 Fire Foam
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CP 643N/644 Firestop Collar
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CP 648-E/S Firestop Wrap Strip
•
CP 680-M/P/PX Cast-In Firestop
Device
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CP 681 Tub Box Kit
•
FS-ONE MAX High Performance
Intumescent Firestop Sealant
The F-rating establishes the minimum amount
of time, under specified conditions, that a firerated assembly must withstand fire penetration
and the T-rating expresses the amount of
time that the firestop system will prevent the
temperature of the non-flame side of the
assembly from rising 325° above the ambient
temperature.
These products were subjected to the
standard 3-ft water column pressure test
for 72 hours* followed by a fire and hose
stream test in accordance with UL 1479.
While firestop systems are installed as
a passive fire containment mechanism,
sprinkler systems serve as active fire
containment. Once triggered, sprinkler
systems reduce the heat source by
directly cooling the fire’s flames as well as
dampening the fuel source by moistening
the flammable materials feeding the fire.
However, in the process of containing the
fire the water source often does a great
deal of damage to the remaining building
structure by subsequently flowing through
penetrations to the floors below. Hilti has
approached this problem by developing the
following line of products and systems that
have successfully been tested to the
Class 1 W-rating requirements:
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Bare metallic pipes, conduits or tubing
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Cable bundles
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Insulated metallic pipes / tubing
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Multiple or mixed penetrants
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Non-metallic pipes, conduits or tubing
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Sheet metal ducts
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CFS-DID Drop-In Device
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CFS-S SIL GG Firestop Silicone Sealant
The Class 1 W-rating is listed on a variety of
Hilti firestop systems covering the following
penetrating material types:
While the W-rating is not mandated by
code requirements, they are often noted by
architects and engineers in specifications
and requested by building owners who
understand the importance of protecting
their properties from water damage. Protect
your multi-story project by adding W-rated
products and firestop systems to your
designs today!
*While UL claims this test procedure helps in determining the
water resistance of firestop systems during the construction
phase it is important to realize that products tested to these
requirements are done so in a fully-cured state. Products
exposed to water prior to curing may not restrict water passage.
06/16 DBS
Resisting Water Passage
Hilti. Outperform. Outlast.
Hilti, Inc. (U.S.) 1-800-879-8000 www.us.hilti.com • Hilti (Canada) Corp. 1-800-363-4458 www.hilti.ca
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