This document discusses various methods for noise reduction from mechanical equipment. It describes using rubber mounts, vibration isolation, and insulation to reduce noise from pumps, generators, ducts, and other machinery. Specific guidelines are provided for vibration isolation of pumps based on horsepower and beam spans. Characteristics of duct systems that influence noise propagation are explained. Different isolation techniques are outlined for controlling noise within air conditioning ducts and from pumps and generators.

1. ACOUSTICS – UNIT 7
NOISE REDUCTION FROM MECHANICAL EQUIPMENTS ,
RUBBER MOUNTS , VIBRATION ISOLATION GUIDELINES ,
CHARECTERISTICS OF DUCT SYSTEM , NOISE IN AC
DUCTS , VIBRATION ISOLATION OF PUMPS AND
GENERATORS
Submitted by
G . Pranay ram
B.Arch, iii/v , sem-2
A N U – C A P

2. NOISE REDUCTION FROM MECHNICAL
EQUIPMENTS
• To adequately define the noise problem and set a good basis for the control strategy, the
following factors should be considered: 1. type of noise 2.noise levels and temporal pattern
3.frequency distribution 4.noise sources (location, power, directivity) 5.noise propagation
pathways, through air or through structure 6.room acoustics (reverberation).
• The need for control or otherwise in a particular situation is determined by evaluating noise
levels at noisy locations in a facility where personnel spend time. If the amount of time
spent in noisy locations by individual workers is only a fraction of their working day, then
local regulations may allow slightly higher noise levels to exist

3. • There are different types of methods to control the noise which is caused due to
mechanical equipment.
• Method – 1 : By surrounding the machine or motor equipment with such material
like insulator clothed hood.[ noise reduction barriers ]
• Method – 2 : Providing the sound diffusion rubber insulation wall like substance
which acts as a barrier between the equipment and the receptors , and by also
providing a thick layers of carpets which have a uneven surface grids on it.

4. NOISE REDUCTION OF MECHANICAL EQUIPMENT
DIAGRAM

5. RUBBER MOUNTS
• Elastomeric vibration mounts, vibration dampers and isolators are all the
same thing. But why are they used?
• If you have ever been near a large machine such as a pump, compressor or
industrial engine you have probably noticed that it produced powerful
vibrations.
• These vibrations cause damage to equipment, prematurely wear out
machines and create unsafe working conditions. Eventually this affects
product quality and can even bring plant production to a stop.

6. • To protect your machinery, workers and profit margin, vibration isolation
mounts are necessary. These devices reduce the amplitude and frequency of
the vibrational waves created by heavy duty machinery.
• A properly sized and installed vibration mount will significantly reduce the
vibration, shock and noise created by the machine, this is because the mount
creates a resilient connection to the machine and transfers the energy from
the machine onto the mount which dampens the vibrations and shocks.
• Vibration damping mounts are commonly made with an elastomer such as
natural rubber which is then bonded to metal. This rubber bonded to metal
vibration mount is then attached to a machine such as a generator and lowers
the natural frequency of the machine below the disturbing frequency, all
without affecting the performance of the machine.

7. • For the reduction of different types of vibrations in industrial equipment's
there are different types of Rubber Mounts.
• They are ,
1. Marine engine mounts
2. Cylindrical mounts
3. Stationary machine mounts
4. Cone and shear mounts
5. Center bonded mounts
6. Electrical panel mounts

8. VIBRATION ISOLATION GUIDELINES
• If the floor is above grade, then SyncroFlo recommends that the skid be a
concrete filled inertia bases with spring isolators for pumps over 7 ½
horsepower. Primary and secondary pump systems should then be isolated
separately. Vibration isolators should be different sized depending on the
span of the beams. See the table below.
• For rigidity, the standard industry practice is to design the inertia base to be
1/10 the longest span between isolators and at least 6” for up to 30 HP, 8”
for up to 75 HP, or 12” if 100 HP or greater.

9. “
”
GUIDELINES TABULAR FORM
CC=Close-Coupled Pump & Motor.
FC=Flex-Coupled Pump & Motor.

10. CHARECTERISTICS OF DUCT SYSTEM
• Ducts vary in their ability to transport signals, weak ducts may only
propagate up to 144Mhz while strong ducts may sometimes propagate
10GHz signals.
• As ducts become stronger and transport higher frequencies the lower
frequencies seem to become weaker.
• Propagation distances of over 2000km have been observed on all amateur
bands from 144MHz to 10GHz

11. • Elevated ducts interact with microwave signals by refraction through the duct
and/or propagation along the duct.
• The surface ducts can be extreme and form a highly microwave reflective
layer close to the ground.
• Surface ducts can propagate signals along the ground until they reach an
obstruction.
• Surface ducts break up due to heating of the ground after sunrise.
• The k-factor fading or sub-refraction does not happen at all except in or very
close to a duct. The k-factor of the gross atmosphere is 4/3 at all times. All
of the effects attributed to k-factor fading can be more correctly explained
by the effects of surface ducts.

12. NOISE IN AC DUCTS
• Generally from the ducts of the AC inlets the noise will also enter from it ,
which is caused due to the vibration of the motors which work in the Air
Conditioner.
• Air Duct Noise Reduction. Noise from air ducts---the tubes made of sheet
metal that carry warm and cool air to vents---can be a big distraction. If you
are trying to sleep, work, watch TV or even carry on a conversation and the
noise is interfering, it's time to implement a buffering strategy

13. AC DUCT
DIAGRAMS

14. • They can be controlled by the using the following materials.
• Insulating Air Ducts : Since air ducts will make noise no matter how well the
HVAC system is designed, properly insulating them is the best strategy to
reduce this noise. It also increases the energy efficiency of your heating or
cooling system. In an existing home, you can usually access air ducts through
attic or crawl spaces or the basement.
• Air Duct Silencers : Since ducts act as 'sound tubes' that amplify the sound
of the fans and blowers around the house, consider installing air duct silencers.
A variety of these products are on the market. They can easily be installed in
existing systems. Sound absorbing materials are placed on the inside of the
duct and can eliminate some of the sound that external insulation cannot.

15. DIAGRAMS SHOWING HOW THE NOISE IS
CAUSED IN AN AC DUCT

16. VIBRATION ISOLATION OF PUMPS AND
GENERATORS
• Generally due to the activities of the motors in pumps and generators the
vibrations are caused
• For the reduction or the control of that vibrations there are different types
of tools and equipment which can reduce them.
• They are 1. Spring Isolators, 2. Fiberglass and Neoprene Isolators, 3.
Isolation Hangers, Flex Connectors and Thrust Restraints, 4. Isolation Bases,
5. Sound and Vibration Isolation Curb.

17. • 1. Spring Isolators
• 2. Fiberglass and
Neoprene Isolators
• 3. Isolation Hangers, Flex
Connectors and Thrust
Restraints
• 4. Isolation Bases
• 5. Sound and Vibration
Isolation Curb

18. DIAGRAMS SHOWING HOW THE TOOLS ARE REDUCING
THE VIBRATIONS

19. REFERENCES
• http://www.kineticsnoise.com/
• http://www.siebeinacoustic.com/
• http://www.avproductsinc.com/
• http://www.syncroflo.com/
• http://www.df5ai.net/
• http://www.geeksonhome.com/
• http://kineticsnoise.com/

20. THANK YOU