Page 50 IM-738
Adjustment of Seismic Restraints
Spring mounted supply air and return air fans may be ordered
with factory installed seismic restraints. The system consists
of four snubbers, one located next to each spring isolator.
These snubbers will allow free movement of the fan assem-
blies during normal operation because normal operation will
not cause fan movements that exceed .25" (6 mm). However,
they will restrain the fan assembly and limit movement to
.25" (6 mm) in any direction if an abnormal condition were
to occur.
The position the fan will assume during normal operation
will be determined by actual job site airflow and static pres-
sure. Therefore, for proper operation the seismic restraints
must be field adjusted as part of the normal "Check, Test and
Start" procedure. When the fan is operating in a normal man-
ner there should be no contact between the snubber restrainer
angle and the snubber neoprene bumper. However, in a "seis-
mic event," the snubber will limit movement of the spring
mounted fan assembly to .25" (6 mm) in any direction,
thereby preventing the fan from being tossed about and dam-
aged, or causing damage.
When a seismic restraint is properly adjusted and the fan is
operating normally, the neoprene center bumper will be cen-
tered within the 2" (51 mm) diameter hole in the restrainer
angle, and the restrainer angle will be centered vertically
between the flanges of the neoprene center bumper. This
results in .25" (6 mm) clearance in all directions. When the
fan is turned off the restrainer angle may come to rest on the
neoprene center bumper.
The seismic restraint is adjustable in all directions. Vertical
slots in the restrainer angle and horizontal slots in the blower
base allow the restrainer angle to be adjusted up and down
and back and forth. The neoprene center bumper is mounted
on a slotted hole allowing its adjustment in and out.
Removing the neoprene center bumper bolt allows removal,
disassembly, and replacement of the neoprene components.
Figure 64. Cross Section of Seismic Restraint
F a n B a s e C h a n n e l
S n u b b e r R e s t r a i n e r A n g l e
A d j u s t U p o r D o w n
o r B a c k a n d F o r t h
S n u b b e r N e o p r e n e
B u m b e r
. 2 5 " ( 6 m m ) G a p
( F a n R u n n i n g )
d j u s t I n a n d O u t
S n u b b e r N e o p r e n e
B u m b e r
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