Product Technical Guides : US-EN Firestop Systems Guide For Specifiers | Page 688

How to estimate amount of Firestop needed for pipe penetrations*
Single pipe, circular opening Single pipe, rectangular opening For multiple pipes in an opening
Use the Estimation Chart (Table 3)
found on page 685. Find the pipe size
across the top of the table and match
it with the hole diameter found along
the side of the chart. The value from
the table represents the volume of
annular space to be filled per side, per
penetration, based on a 1/2" depth of
firestop. 1. C
 alculate the area of the pipe. For
schedule 40 steel pipe, use the
Calculation Chart For Pipe Areas
(Table 1) found on page 685. Find
the pipe size that is used and note
the Area located in the far right
column OR calculate the total cross-
sectional area of the penetration
using the following formula (note: all
values should be in units of inches): Use the methods stated previously, but
add all of the penetration areas (A p )
together before subtracting from the
total area of the opening (A o ).
A P = (r P2 ) x 3.14
A P = total area of penetrating pipe
 utside radius of
r P = o
penetrating pipe = outside diameter

_______________

2
2. Calculate the area of the opening (all
values in units of inches):
A o = area of opening
Rectangular opening: A o = length x width
Circular Opening: A o = (r P2 ) x 3.14
3. Subtract the area of the penetrating pipe
from the area of the opening and multiply
by the depth of the firestop required:
Total firestop required = (A o - A P ) x F D
F D = firestop depth (in inches)
Total volume of firestop required per
penetration. For wall systems requiring
firestopping on both sides, multiply by
2.
Sample Problem
APPLICATION: 3-hour fire rated concrete floor. Opening size is 8" diameter I.D. circular opening with nominal 6" dia. steel pipe. Use
UL System C-AJ-1226 (1/4" depth FS-ONE MAX)
A o = 8" diameter 50.24 in 2
diameter - ________
34.19 in 2
A P = 6"

16.05 in 2 x 0.25" = 4.0 in 3 of FS-ONE MAX
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