Greenheck Support Mullions User Manual
D
Document number 462105
®
FABRICATION AND FIELD
INSTALLATION INSTRUCTIONS
Support Mullions for use in Oversize Openings
These installation instructions apply to the fabrication and construction of generic support mullions. Support mullions
are necessary whenever static fire dampers are installed into a vertical opening that is larger than the largest UL rated
size for that damper. The mullions allow construction of a fire barrier that is larger than the maximum available size.
The opening must not exceed 120 in. (3048mm) high, but can be any width provided a vertical support mullion is used a
maximum of every 120 inches (3048mm).
To properly use support mullions they must be fabricated and installed according to the following instructions.
Application
Generic steel mullions can be used to separate vertically
mounted galvanized steel fire dampers in wall openings
larger than the UL permitted multiple damper assembly
size. Mullions can either be used vertically, horizontally or
both to split up a vertical wall opening requiring use of a
damper having a 1
mullion span is 120 in. (3048mm) plus expansion allowance
when used either horizontally or vertically.
Sleeves are to be around each damper assembly. Mullions
are not intended to be in the airstream, (i.e. exposed to
flow) or to be a part of the ductwork.
1
/2 hour fire resistance rating. Maximum
Wall Opening
Steel mullions are intended for use in a concrete block or
solid concrete wall.
Hollow concrete blocks are to be filled with concrete
(minimum 3500 psi) to permit proper mullion anchoring.
Wall thickness is to be 7 in. (178mm) minimum, 12 in.
(305mm) maximum.
Retaining Angles (Typical)
Sleeve (Typical)
Wall Mullion Cap
B-B (Typical)
Mullion Assembly
A-A (Typical)
Horz. to Vert.
Mullion Cap
C-C (Typical)
G
G
G
E
G
F
E
F
SPECIAL NOTE: Support
mullions may only be used
D
with static-rated fire damper
assemblies; they cannot be used
to install combination fire-smoke
dampers in wall openings that
exceed the maximum UL-approved
size for the fire-smoke damper
model being installed.
Support mullion assemblies consist of three basic parts:
Formed Section View (2 req’d)
the wall mullion cap, the horizontal to vertical mullion cap
and the mullion sections. Determine the quantity of each
piece required to complete the installation.
Dimensional Information shown in inches (mm).
Table 1
Opening Width/Height D H
12 (305) 11½ (292) 3¼ (83)
24 (610) 23½ (597) 3 3/8 (86)
36 (914) 33 3/8 (847) 3½ (89)
48 (1219) 47¼ (1200) 3 5/8 (92)
60 (1524) 59 1/8 (1501) 3¾ (95)
72 (1829) 71 (1803) 3 7/8 (98)
84 (2134) 82 7/8 (2105) 4 (102)
96 (2438) 94¾ (2406) 4 1/8 (105)
108 (2743) 106¾ (2711) 4 ¼ (108)
120 (3048) 118¾ (3016) 4 3/8 (111)
E = Wall Thickness - 1/2 in. (13mm)
F = Wall Thickness +
1
/4 in. (6mm)
Fabrication of Wall Mullion Caps
Wall mullion caps must be constructed from 12 ga. steel
with a minimum yield strength of 42,000 psi.
1. Fabricate the formed section as shown to right.
2. Shear the cap end plate to required dimensions.
3. Weld the cap end plates to the formed section with
1/8 in. (3mm) fillet welds completely around the top
edges of the formed section.
4. Drill and countersink 8 holes ( 4 on each side) for
¼-20 flat head machine screws.
Fabrication of Mullion Sections
Mullions must be constructed from 16 ga. (1.5mm) steel
with a minimum yield strength of 42,000 psi.
Important: The “D” dimension shown has been calculated
to include the necessary clearances required for thermal
expansion in the mullions. The values can be found using
the wall opening dimensions and tables on this page.
1. Form two identical pieces of mullion section as
shown.
2. Connect the two mullion sections together. Use 3/16
in (4.7mm) steel blind rivets of 3/4 in. (19mm) long
intermittent welds 12 in. (305mm) on center and a 6
in. (152mm) maximum from both ends.
Important: Both sides of the mullion piece should be
fastened using the method described above.
8
33/
7
8
/
3/16 in. typical
rivet location
2 2C-4
C= Wall Thickness
2
31/
D
3/16 in. blind rivet (stl) or 3/4 in.
long intermittent welds 12 in. on
center, 6 in. maximum from both
ends, both sides of assembly.
3
4
/
Assembled View
Detail A-A
Mullion Assembly
All dimensions shown are in inches.
13
2 2
16
/
1
H
H
Formed Section
End View
Weld
E/8
E/4
Detail B-B
E/4
E
E/4
E/8
4
31/
Cap End Plate
(2 req’d)
Wall Mullion Cap
Assembled View
1
/4
3
H
Wall Mullion Cap
All dimensions shown are in inches.
Fabrication of Horizontal to Vertical
Mullion Caps
Horizontal to vertical mullion caps must be constructed
from 12 ga. (2.7mm) steel with a minimum yield strength of
42,000 psi.
Important: The H, E and F dimensions shown have been
calculated to provide the correct performance. The values
can be found by using the wall opening dimensions and
Table 1.
1. Form the horizontal mullion channel as shown.
3
2. Drill 12,
mullion channel using the dimensions shown.
3. Form the center channel as shown.
/16 in. (4.7mm) dia. holes into the horizontal
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