TM 5-805-4/AFJMAN 32-1090
tions from this assembly to other equipment
turbine is used to drive reciprocating-compressor
should contain flexible connections (see para B-5b).
refrigeration equipment or reciprocating-type gas
d. Rotary-screw-compressor refrigeration equip
compressors.
ment. The recommended vibration isolation for
this equipment are given in table 8-4.
system, vibration isolation should be provided in
e. Centrifugal-compressor refrigeration equipment.
accordance with recommendations given for either
The recommended vibration isolation for this equip-
the main power drive unit or the driven unit,
ment, including the drive unit and the condenser
whichever imposes the more stringent isolation
and chiller tanks, are given in table 8-5.
conditions.
f. Absorption-type refrigeration equipment. The
recommended vibration isolation for this equip-
tion for indoor transformers are given in table
ment are given in table 8-6.
8-12. In addition, power leads to and from the
g. Boilers. The recommended vibration isolation
transformers should be as flexible as possible. In
for boilers are given in table 8-7. These apply for
outdoor locations, earthborne vibration to nearby
boilers with integrally attached blowers. Table 8-2
neighbors is usually not a problem, so no vibration
should be followed for the support of blowers that
isolation is suggested. If vibration should become a
are not directly mounted on the boiler. A flexible
problem, the transformer could be installed on
connection or a thermal expansion joint should be
neoprene or compressed glass fiber pads having
installed in the exhaust breaching between the
1/4-inch static deflection.
boiler and the exhaust stack.
n. Air compressors. Recommended mounting for
h. Steam values. Steam valves are usually sup-
centrifugal type air compressors of less than 10 hp
ported entirely on their pipes; paragraph 8-5a
are the same as those given for motor-pump units
should be applied to the resilient support of steam
in table 8-10. The same recommendations would
piping, including steam valves.
apply for small (under 10 hp) reciprocating type
i. Cooling towers. The recommended vibration
air compressors. For reciprocating type air com-
isolation for propeller-type cooling towers are
pressors (with more than two cylinders) in the 10
given in table 8-8. Additional for the installation
to 50 hp range, the recommendations given in
are given in paragraph 8-3f, which describes the
table 8-3 apply for the particular conditions. For
Type V mounting assembly. The recommended
10 to 100 hp, one or two cylinder, reciprocating
vibration isolation for centrifugal-fan cooling tow-
type air compressors, the recommendations of ta-
ers are given in table 8-9.
ble 8-13 apply. This equipment is a potentially
j. Motor-pump assemblies. Recommended vibra-
serious source of low frequency vibration in a
tion isolation for motor-pump units are given in
building if it is not isolated. In fact, the compres-
table 8-10. Electrical connections to the motors
sor should not be located in certain parts of the
should be made with long "floppy" lengths of
building, even if it is vibration isolated. The
flexible armored cable, and piping should be resil-
forbidden locations are indicated in table 8-13.
iently supported. For most situations, a good isola-
When these compressors are used, all piping
tion mounting of the piping will overcome the
should contain flexible connections (para 8-5b),
need for flexible connections in the pipe. An
and the electrical connections should be made with
important function of the concrete inertia block
flexible armored cable.
(Type II mounting) is its stabilizing effect against
o. Natural-gas and liquid-fuel engines, recipro-
undue bouncing of the pump assembly at the
cating and turbine. Vibration isolation of these
instant of starting. This gives better long-time
engines is discussed in detail in TM 5-805-g.
protection to the associated piping. These same
8-5. Vibration Isolation-Miscellaneous.
recommendations may be applied to other motor-
driven rotary devices such as centrifugal-type air
a. Resilient pipe supports. all piping in the MER
compressors and motor-generator sets in the power
that is connected to vibrating equipment should be
range up to a few hundred horsepower.
supported from resilient ceiling hangers or from
k. Steam turbines. Table 8-11 provides a set of
floor-mounted resilient supports.
general isolation recommendations for steam-
(1) As a general rule, the first three pipe
turbine-driven rotary equipment, such as gears,
supports nearest the vibrating equipment should
have a static deflection of at least one-half the
generators, or centrifugal-type gas compressors.
static deflection of the mounting system used with
The material given in table 8-5 applies when a
s t e a m turbine is used to drive centrifugal-
that equipment. Beyond the third pipe support, the
static deflection can be reduced to 1/4 inch or 1/2
compressor refrigeration equipment. The recom-
inch for the remainder of the pipe run in the MER.
mendations given in table 8-3 apply when a steam
8-10
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