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STRUCTURAL ACOUSTIC INSULATION OF URBAN SUPERMARKETS.

Vibration isolation of urban supermarkets

 

Supermarkets are a source of perturbance in buildings. Proximity shop or urban supermarkets with wider opening hours during the week provide flexibility to consumers. People talking, castor wheels, HVAC, Compressors, forklifts introducing incoming goods, hydraulic load lifts, loudspeaker announcements.., make supermarkets often an unwanted neighbour. Constructing a supermarket on an existing building can become a challenge if acoustic insulation measures have not been taken in account.

In order to avoid noise complaints, AMC MECANOCAUCHO’s technical department has been assisting acoustic engineers, contractors and acoustic installation specialists for more than 20 years in Europe. On this article a summary of past experiences will be presented as a guidance. This article’s goal is to show different possible solutions per area of the Supermarket and expected acoustic results. Nevertheless AMC-MECANOCAUCHO always recommends dealing with an acoustic consultant, who will be able carry out an individualized study, providing corrective measures based on the technical complexities of work.

On the following link a worldwide list of acoustic consultant associations can be obtained. You can also contact us if you want to get in touch with an specialized acoustic consultant that will have experience treating cases like yours.

Media, internet forums, lawyers or even legal disputes show how Supermarkets face noise problems. No matter the country or if it is an apartment house or a Hotel. Some example are shown below:

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If we take in consideration, Hotel buildings, the demand for acoustic insulation and vibrations is increasingly high. A recent analysis of online guest reviews done by ReviewPro reveals that noise is the number one most common complaint by consumers in all but one city. The reviews came from 5,683 hotels in 20 key tourist destinations.

In newly built constructions or in renovation projects, AMC Mecanocaucho provides products that can solve this noise disturbance. In a Supermarket there are plenty of sources of noise, for example:

  • Incoming goods areas/ramps where transfer of goods from the lorry are done from forklifts to pallet trucks . This transfer of goods can generate noise levels of 80 to 85dB A around 30 mins per Lorry. Starting early in the morning (6:00 AM).

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“Incoming material areas can generate noise levels of 80 to 85dB A around 30 mins per Lorry. Starting early in the morning normally 3 lorries are usual for busy supermarkets.”

  • Compressors and cooling equipment machinery depending on the temperature of the supermarket automatically switch on periodically (in some cases every 5 minutes) during 10 minutes. They can raise the noise levels from 45 to 55-60dB A. The change

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“Switch on/off may cause sudden changes in noise levels from 45 to 55-60dB A. Depending on the temperature, these changes can be very frequent during 24h”

  • Service lifts generate structural noise/vibration and if they do not have a proper acoustic insulation, they transmit noise to the adjacent buildings. Addressing the vibration problems and providing a correct acoustic insulation will save claims.

Video 1: Demo of service lift noise

Supermarket service lifts are a major source of complaints. Addressing the vibration problems and providing a correct acoustic insulation will save noise claims.

  • Emergency generator sets also generate structural noise/vibration and if they do not have a proper acoustic insulation, they transmit noise to the adjacent buildings. Addressing the vibration problems and providing a correct acoustic insulation will save claims.

  • Castor wheels and human activity generate structural noise, they transmit noise to the adjacent buildings. Addressing the vibration problems and providing a correct acoustic insulation will save claims.

AMC-Mecanocaucho, has a technical department and a range of products that can meet the highest demands in terms of acoustic insulation. It has a wide range of soundproofing solutions for the different noise and vibration sources discussed above. The integration of elastic suspensions can reduce the transmitted noise by more than 20 dB, transforming an annoying room into one with complete acoustic insulation.

BOX IN BOX CONCEPT AND MACHINE ISOLATION.

Box-in-box is a construction technique that allows a space within a space to be insulated against unwanted extraneous noise and vibration. Such extraneous noise may be airborne (travelling through the air) or they may be structure-borne – travelling through the ground and building structure. Noise is an audible vibration, therefore machinery or equipment that vibrate can generate noise disturbance, therefore should have also an acoustic insulation.

“Noise is an audible vibration”

Discover how “Silent Supermarket” achieves a correct structural acoustic insulation .

This is principle of this soundproofing technique consists on decoupling the floor, walls and ceiling products to correct the airborne and structure borne noise transmission. This is often achieved with elastic anti vibration mounts supporting the suspended ceiling; called acoustic hangers, walls anti vibration mounts, called acoustic wall ties or floors, called floating floor anti vibration mounts. Noise absorption and mineral wool based acoustic insulation materials are often used on the air gaps, they provide thermal and reduce the reverberation inside the air gaps.

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“The strategy of decoupling rigid structures, achieves successful acoustic insulation results.”

Visual demo of decoupling.

There are plenty of sources of structural noise in Supermarkets, and many possible mounts/systems according to the budget and level of soundproofing required.

Since the structure of the building plays a key role, the soundproofing solutions may not be “plug and play”. Supermakets have their own natural frequencies and vibration shapes. AMC MECANOCAUCHO strongly advices to contact a professional acoustic consultants. On the following link a worldwide list of acoustic consultant associations. You can also contact if you want to get in touch with specialized acoustic consultant that will have experience treating cases like yours. AMC-MECANOCAUCHO visits acoustic consultants and develops its products jointly with the advice of many of them across the world.

AMC ENGINEERING services for acoustic consultants.

In order to reduce the structural transmission of noise, elastic elements are used. The elasticity of the anti vibration mount plays a major role on the transmission of structural noise.

There are several elastic materials that can be used, such as springs, rubber, Sylomer® or even combination between them. The parameter that is used to define how elastic is a material is called stiffness (k). This parameter defines the force over displacement (N/mm or Lb/in).

Buildings complex structures and simplifications do not always work, but it can be said that the higher the stiffness of the anti vibration mounts, (acoustic hangers, wall ties or floor anti vibration mounts) the higher the natural frequency. The higher the natural frequency, the most likely is to interfere with the disturbing frequency created by machines or human activity. This leads us to lower vibration/acoustic insulation, therefore hard materials are not the best materials when soundproofing premises.

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“The higher the stiffness of the anti vibration mount, the higher its natural frequency. Stiff materials, are not the best materials when soundproofing premises.”

Doing a simplification, it can be said that the softer the anti vibration mounts are, the higher the acoustic insulation / lower structure borne noise.

Special care must be taken to coil springs. Even if they may have low stiffness, high frequencies can go through the spring and create resonances that can be audible if the spring is not surrounded with elastomeric materials.

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“The lower the natural frequency is, the wider is the spectra of frequencies that will be isolated”

VIBRATION ISOLATION AREAS WITHIN SUPERMARKETS.

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1. Incoming goods area.

2. HVAC , Cooling compressors and machinery in general.

3. Ducts, piping lower.

4. Ground parking doors.

5. Ceilings and Walls

6. Shopping cart & human activity noise.

7. Service Lifts

8. Loudspeaker isolation.

9. Electric transformers.

1.- Incoming goods area.

This is a major concern area. Trucks have to be offloaded and goods have to be transferred to pallet trucks and then to the shelves.

Since the goods must be before the opening hours of the supermarket this can start early in the morning, when neighbours are still sleeping.

An offload of a truck can have 30 minutes of duration. Busy supermarkets can have easily 3 trucks to offload every morning.

The pallet trucks are an important source of structural noise and vibrations that are transmitted to the adjacent rooms, creating bothersome noise for their residents.

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If we want that the dreams of neighbours are not turned into a nightmares, floor decoupling of goods-in area is a necessary measure. Suspending elastically the floors is one of the most effective measures to reduce the noise transmission. The noise generated on a floor can travel through rigid structures and can be audible on multiple floors across the building.

AMC Mecanocaucho offers a wide acoustic insulation solution that largely attenuates structure-borne noise and vibrations. The solution lies in installing an anti vibration mount under to the good in area such as Sylomer®/ Sylodyn® Springs or rubber based materials.

This treatment is very simple to apply. The system involves fitting an elastic sheet under a lost formwork, covering the entire surface onto which the goods in area will subsequently be installed. It is essential to fit the elastic suspension to both the floor and the walls of the area to ensure complete elastic separation and prevent acoustic bridges from occurring. Below images show the process.

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Solutions with punctual bearings allow lower cost solutions, the tradeoff is the additional installation process.

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Floor based on point bearings such as floor blocks, these systems can prevent the transmission with improvements of up to 31 dBs in impact noise. The construction principle admits both concrete and dry floors based on boards.

Nevertheless there are a wide variety of floating floor anti vibration mounts. The parameters for the selection will depend on the requirement for acoustic insulation, available space, requirement of levelling in case that the Supermarket must be renovated, requirement to insert cables beneath the floor (technical floor) and of course cost of the system. In order to have a clear view of all the possibilities below there is an overview of the different floating floor anti vibration mounts available.

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Fzh Spring+Sylomer®

Fzh+Sylomer®

Vibrabsorber+Sylomer®

Granab®

AFB Sylomer®

Sylomer® Pad

BF floor bearings

Tabiabsorber

Natural frequency Hz

3,5-8Hz

8-14Hz

3,5-8Hz

9-25Hz

8-14Hz

10-15Hz

12-20Hz

18-30Hz

For concrete or dry construction?

Concrete

Concrete

Dry

Both

Both

Both

Both

Both

Minimum espace requirement.

15mm (5/8’’)

15mm (5/8’’)

100mm (4’’)

30mm (1.1/5’’)

50mm (2’’)

12mm(1/2’’)

28mm(1,1/10’’)

5mm, (1/5’’)

Levelling capability?

Yes

Yes

No

Yes

No

No

No

No

Technical floor?

No

No

No

Yes

No

No

No

No

Cost

Premium

Mid

Mid

Mid

Low

Low

Top Low

Top Low

Data sheet

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2.- Frozen food cooling compressors, HVAC , dairy products freezers and piping.

Eccentric vibrating machinery provide installation challenges in buildings. The vibration levels disturb adjacent neighbours causing noise complains.

In order to reduce the level of vibration on the machinery it is advisable to install the machine with anti vibration mounts that provide a sufficiently low natural frequency. The lower the vibration level on the slab, the lower vibration and audible noise will be transmitted to the adjacent rooms. This allows a high degree of vibration isolation.

HVAC, and frozen area compressors are extremely necessary in supermarkets. They keep frozen food at the necessary temperature even in hot climate. The warmer the climate is, the greater the power that is required. This often requires more compressors. This increases the vibration amplitude-severity.

Therefore, in order to achieve a successful soundproofing, anti vibration mounts that have low stiffness, will help transmit less vibration to slab. False myths among contractors, let them think the way to resolve structural noise problem was making thicker slabs. The thicker is an slab, the higher the natural frequency.

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This measure does not avoid the transmission of structural noise. Decoupling it is the way to go. Therefore reducing the stiffness can allow us obtain satisfactory results. On the image below a reduction of 98% Vibration was achieved. By adding elasticity to the suspended element.

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The lower the vibration level on the slab, the lower vibration and audible noise will be transmitted to the below room. Spring anti vibration mounts that incorporate a soundproofing material like Sylomer® underneath and have lateral buffers against wind are effective for achieving good results. More info on this link: Vibrabsorber+Sylomer® antiseismic.

“Spring anti vibrationmounts that incorporate a soundproofing material like Sylomer® underneath and have lateral buffers against wind are effective for achieving good results. More info on this link: Vibrabsorber+Sylomer® antiseismic.”

AMC-MECANOCAUCHO has developed an online tool that allows engineers to make their own calculation. This calculation software calculates the vibration isolation efficiency requiring simple information as:

1. Total load.

2. Centre of gravity position.

3. Position of anti vibration mounts

4. Disturbing frequency

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Online calculation software

Ask for user and password on this link

In case that the load is evenly distributed across all mounting points, AMC-MECANOCAUCHO has developed a mobile app called Vibration Isolator pro that allows engineers to make their own calculations. This app provides calculates the vibration isolation efficiency requiring simple information as:

  1. Total load.

  2. Disturbing frequency

  3. % of vibration isolation required.

“The app that allows you to select the vibration isolator that you need”

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Not all the machinery requires high specification Spring anti vibration mounts or vibration isolators, small machinery, dairy product freezers, small compressors can be isolated on a cost effective way using a soundproofing material called Sylomer®. This soundproofing material comes in different colours according to the load capacity. There are products that use this elastic material in form of machine feet, they are called TSR+Sylomer®.

They provide a natural frequency of around 10Hz. So they are convenient for those machines where the peak measured on the Vibration Isolator pro app, give as a peak of 30Hz or higher.

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3.- Ducts and piping.

Ducts, especially when they are metallic, they are likely to cause vibrations and noise. This vibration can travel through rigid fixation studs to upper floors causing a disturbing noise. It is advisable that ducts get decoupled. Acoustic hangers depending on their stiffness these anti vibration mounts can provide a higher or lower acoustic insulation.

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Ducts isolated on acoustic hangers can provide a correct structural and acoustic insulation depending on their natural frequency.

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In order to select the correct pipe anti vibration mount, we need to know the load per point and the disturbing frequency. The disturbing frequency is measured in Hz. Acoustic consultants are equipped with vibration measurement equipment, they would be able to give you correct advice.

In case that an acoustic consultant cannot be contacted, a possible way of knowing the frequency is using the Vibration isolator pro app or the compatible VIP accelerometer that is available for a price of 300€.

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Watch VIP accelerometer in action

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Should you be interested in this topic do not hesitate to contact our applications engineers. They will be able to help and give you input. Contact form AMC-MECANOCAUCHO® Applications engineers.

4.- Parking/Garage doors.

It can be annoying to have a garage door that rattles, squeaks, and shrieks as it opens and closes. Some Supermarkets guests claim they can hear and feel their garage door opening in every room. Garage doors create vibrations during opening and closing. This results in loud and distracting noises. It might not be a problem during the day, but if you are trying to sleep, it can be disruptive.

Reduce the vibrations, and you will reduce the noise level. The first steps should be to do a maintenance first on the rollers, replace them if they are worn out change and lubricate them. This will help the soundproofing.

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Reduce the vibrations, and you will reduce the noise level

Your garage door may also be noisy because the acoustic insulation strip on the bottom of the door is worn out or missing. With a missing insulation strip, you will feel cold and wet coming into your garage and hear a loud banging noise when the door is closed. You can easily replace this acoustic insulation strip by removing the old one and purchasing a roll soundproofing material such as Sylomer®. Slide-out the old and worn strip and slide the new Sylomer® through the tracks in the door.

If after the noise is still there, we may need use anti vibration mounts under the engine or decouple the frame of the door with anti vibration mounts.

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If maintenance operations do not reduce the noise, decoupling of engine and frame may address the problem.

5.- Ceilings and walls.

Following the box in box concept, the walls and ceilings must also be decoupled if we want to have a correct soundproofing of the room.

Using or not a suspended ceiling with acoustic hangers can provide provide important gains in airborne and impact noise. If we follow the below structure, the difference in impact noise is 31 dB and 20dB for airborne noise

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“Using or not using a suspended ceiling with acoustic hangers can represent a difference of 31dB in impact noise and 20dB in airborne noise”.

The concept is very similar to the floating floor anti vibration mounts, there is a wide variety of systems The parameters for the selection will depend on the requirement for acoustic insulation, available space and of course cost of the system. In order to have a clear view of all the possibilities below there is an overview of the different floating floor anti vibration mounts available.

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SRS+Sylomer®

Springtec+Sylomer®

SRB

VT High deflection

VT

Springtec

Akustik+Sylomer®

Akustik

Natural frequency Hz

4-8Hz

4-8Hz

4-8Hz

2-6Hz

4-8Hz

4-8Hz

7-13Hz

11-15Hz

Filter to high frequencies

High

High

Med

Low

Low

Med

High

Med

Minimum espace requirement.

150mm (5,9’’)

112mm (4,4’’)

150mm (5,9’’)

220mm (8,66’’)

120mm (4,72’’)

86mm(3,38’’’)

47mm(1,85’’)

47mm(1,85’’)

Load Range

25-150Kg

(55-330lbs)

2-60Kg

(4-130lbs)

25-150Kg

(55-330lbs)

25-446Kg

(55-983lbs

25-750Kg

(55-1650lbs)

2-60Kg

(4-130lbs)

5-150Kg

(11-330lbs)

15-150Kg

(33-330lbs)

Cost

Premium

Premium

Medium

Premium

Medium

Med

Low

Top Low

Data sheet

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More information on the use of acoustic hangers, considerations for a correct selection and benefits in acoustic insulation click here.

AMC-MECANOCAUCHO has developed a mobile app called Acoustic hanger pro that allows engineers to make their own calculation and selection of the acoustic hanger or floor mount. This calculation software provides calculations of vibration isolation efficiency requiring simple information as:

  1. Distance between hangers/floor anti vibration mounts.

  2. Natural frequency required.

  3. Position of hangers/floor anti vibration mounts.

“The app that allows you to select the acoustic hanger or floor mount that you need”

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Following the box in box construction principle where floors and ceilings are decoupled, we must not forget about the walls. The structural noise travels also through walls, having an elastic wall tie avoids the transmission of vibrations through the wall.

“Structural noise also travels through the walls”

“Having an elastic wall tie avoids the transmission of vibrations through the wall.”

6.- Shopping carts and Human activity noise.

Although the wheel technology can be advanced for the shopping carts, wear of the carts and stocking areas of the carts are the areas where they generate noise problems.

Priority should be given to the areas of deposit and as the shocks exerced to the carts generate a disruptive noise that can travel through structures if they are not decoupled. It is highly recommended to support elastically these areas.

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Deposit of carts is a hot spot for noise in majority of urban supermarkets.

Entrances of supermarket often contain this area of deposit and generally there is a ramp to access to the supermarket ground. This irregularity on the ground generates often impacts on the wheels that irradiate noise to the building. It is convenient to install a decoupling layer of elastic material. Good results have been obtained with 25mm /1 inch of Sylomer® SR-11.

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Floating floors using Sylomer® SR-11 in have shown good results for decoupling shopping cart deposit areas.

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Ride irregularities provoked by small sized tiles provoke impact on the wheels that make structure and airborne noise within the supermarket. The smaller the tiles are, the higher is the amount of impacts that receive the wheels. This accelerates the wear of the tires, which subsequently generate higher noise.

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Small size tiles accelerate wear of the castor wheels and provoque louder environments.

7.- Service lift acoustic insulation.

Service lifts in Supermarkets present the potential for intrusive noise and vibration to the dwelling units. The adverse noise and vibration can result from the lift equipment located in the machine rooms or the shafts. The impacts can be significant issues related to the acoustic insulation, sleeping conditions of the neighbours. In fact, noisy lifts are one of the most important sources of complains in Supermarkets.

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There are often challenges to identify the transmission path (airborne vs. structure borne) and how the transmission paths can be mitigated to reduce the noise and vibration. Issues relating to the reliability and safety of the elevator operation can introduce difficulties and conflicts with implementing vibration isolators.

From a structural noise point of view the following areas should be addressed:

A.- Engine.

B.- Interaction of Rails and lift cabin guide.

C.- Fastening of the rails to the Building.

D.- Decoupling electrical current noise generation

E.- Hydraulic pipes should be decoupled.

From an airborne noise point of view the following areas should be addressed:

A.-Lift doors

B.-Door enunciators.

C.-Lubrification of mechanical components.

D.-Machinery encapsulated with Akustikabsorber® material, helps to reduce noise emissions.

The below cross section can show the type of soundproofing solutions that lead to noise and vibration mitigation.

Supermarket service lifts are a major source of complaints.

Demo video of a service lift

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Should you be interested in this topic do not hesitate to contact our applications engineers. They will be able to help and give you input. Contact form AMC-MECANOCAUCHO® Applications engineers.

8.- Loudspeaker isolation.

A cost effective way to reduce the structural noise of a loudspeaker is by decoupling through elastic elements such an acoustic hanger. This way the vibrations remain on the loudspeaker and do not travel to the structure as ground borne noise. Acoustic hangers that provide an isolation to low frequencies (Spring) and high frequencies (Sylomer®) provide good results avoiding that neigbours hear announcements of the supermarket through the structure of the building. An example of this product is the ST+Sylomer® acoustic hanger specially designed for suspension of loudspeakers.

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ST+Sylomer® acoustic hanger specially designed for suspension of loudspeakers.

AMC-MECANOCAUCHO has developed a mobile app called Vibration Isolator pro that allows an easy selection of the acoustic hanger for the loudspeaker. This app provides calculates the vibration isolation efficiency requiring simple information as:

  1. Total load.

  2. Disturbing frequency (using the mobile phone accelerometers)

  3. % of vibration isolation required.

“The app that allows you to select the vibration isolator that you need”

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9.- Electric Transformers.

Supermarkets require high electric power for their operations. The main cause of transformer noise is the Magnetostriction Effect. The alternation current that flows through an electrical transformer's coils has a magnetic effect on its iron core. It causes the core to expand and contract, resulting in a humming sound. Due to this reason transformers are another source of noise that causes claims in Supermarkets.

The alternation current that flows through an electrical transformer's coils has a magnetic effect on its iron core. It causes the core to expand and contract, resulting in a humming sound.

Demo video of an electric transformer

In order to reduce the level of vibration transformer it is advisable to install them with anti vibration mounts that provide a sufficiently low natural frequency. The lower the vibration level on the slab, the lower vibration and audible noise will be transmitted to the adjacent rooms. This allows a high degree of vibration isolation.

Therefore, in order to achieve a successful soundproofing, anti vibration mounts that have low stiffness, will help transmit less vibration to slab. False myths among contractors, let them think the way to resolve structural noise problem was making thicker slabs. The thicker is a slab, the higher the natural frequency.

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This measure does not avoid the transmission of structural noise. Decoupling it is the way to go. Therefore reducing the stiffness can allow us obtain satisfactory results. On the image below a reduction of 98% Vibration was achieved. By adding elasticity to the suspended element.

AMC-MECANOCAUCHO has developed an online tool that allows engineers to make their own calculation. This calculation software calculates the vibration isolation efficiency requiring simple information as:

1. Total load.

2. Centre of gravity position.

3. Position of anti vibration mounts.

4. Disturbing frequency (Normally 50-60Hz).

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Online calculation software

Ask for user and password on this link.

Depending on the requirement of isolation several AMC-MECANOCAUCHO has several alternatives.

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AMC-MECANOCAUCHO Transformer mounts

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Vibrabsorber+Sylomer ® mounts

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TSR+Sylomer® pads

This is an overview of the different acoustic insulation / soundproofing solutions that AMC-MECANOCAUCHO has been working over the 50 years of presence on the building acoustics sector.

Do you have questions? A particular case that you would like to solve? You can contact us by clicking on this link.