TABLE 1A
Vibration Isolator Types and Minimum Static Deflection
(MSD, inches) for 4-8 inch slab on grade and column supported.
Column
Slab on earth
31-40 feet
41-50 feet
Spacing
and 0-30 feet
Equipment
Type
MSD
Type
MSD
Type
MSD
_________
(Note (1))
(Note (1))
(Note (1))
Up to 1000
NM
0.35
NM
0.35
S
3.5
lbs.
Over 1000 lbs.
SV
1.0
SV
1.0
SV
1.0
NOTES: (1)
Equipment Vibration Isolation Schedule Designations
(Hyphenated designations are combinations of the following:)
B
- Welded structural steel bases.
H
- Spring isolators (suspended equipment and piping). Where
required, provide with adjustable preloading devices.
HR - Thrust restraints
I
- Concrete inertia bases with steel forms.
NM - Neoprene mounts.
NP - Neoprene pads.
R
- Structural steel rail for equipment mounts.
S
- Freestanding spring isolators (floor-mounted equipment).
SV - Freestanding spring isolators (floor-mounted equipment).
SX - Freestanding spring isolators with adjustable cushioned
vertical stops and cushioned horizontal stops
(floor-mounted equipment). Protected spring isolators SX
may be substituted wherever S or SV is specified and
shall meet all requirements.
(2)
Fans
a.
When fan motors are 75 hp or larger, use the deflection
requirements for the next wider column spacing. Except
for building slab on grade a minimum of 2.5 inches should
be used unless larger deflections are specified in the
centrifugal blower table.
b.
Provide sway brace isolators for tubular centrifugal and
axial fans when the fan pressure exceeds 4 inches water
column.
c.
Provide inertia bases for all fans in lieu of structural
steel bases or rails specified above when the fan pressure
exceeds 4 inches water column.
SECTION 15070N
Page 16
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