Anti-vibration pads are instruments that help reduce the noise that comes from an air condition unit. It also makes a good cushion for the vibrations that is created from the unit. Often, the rooftop-mounted air conditioners are the ones that create structural vibration and noise in a house or in a building. With the help of an anti vibration pad installed in the air condition, it can help reduce the transfer of vibration from the units to the walls floors & ceilings inside a structure. This sturdy cushion like pads fit directly under each of the four air conditioner feet for a quieter environment.

Follow the steps given below that guides you to dampen the sounds & vibration by installing anti-vibration pads under the air conditioner.

• Your first step is to turn off the circuit breaker at the main electrical panel & make sure that the power is cut off from the air condition. It is always safer to work around electrical appliances with the power off, to prevent any kind of accidental electrical shocks.

• Now, tilt the air conditioner slightly to the side & clean away any debris from under the lifted air conditioner feet with a rag or a hand brush. Dirt & debris makes a poor base for the anti-vibration pads causing the air conditioner to sit out on an uneven level.

• Now slowly place the anti vibration pads under each of the lifted foot of an air conditioner

• Check, whether the anti vibration pads that are placed, are in the right position & centered perfectly under the air condition.

• Turn on the power back on to the air conditioner& allow the system to work normally.  Observe the air conditioner to see if the anti vibration pads are effective & restricts less vibration and noise.

How to select an isolator

• Determine the type of machine and the load of the unit that requires isolation.
• Determine the lowest critical frequency of the system like the RPM of the motor, rate at which a cylinder strokes, output speed of a speed reducer etc.
• Select an appropriate isolator by using the information charts that comes with each product. An appropriate isolator will create a system natural frequencies to at least one-third lower than the current frequency.
• Select the isolator that meets all the technical and physical requirements of your system.
• Before selecting isolation equipment consult an expert since a bad design can worsen the condition and affect the vibration damping.

Types of isolators

Rubber isolators are available in pad and molded configurations. While rubber isolation pads are used in single or multiple layers, the molded rubber isolators come in a range of 30 to 70 duro meter.  An isolator would be considered ineffective if the material in excess of 70 duro meters. Isolators are designed for a maximum deflection of up to 13 mm. These solid rubber pads provide high load capacities and deflection. These equipments are used as noise barriers under columns and for pipe supports. These pad work well when they are properly loaded and the mass load is evenly distributed on the entire pad surface.

Isolation hangers are another type of isolators made of rubber or spring or combination of both and used in suspended pipe and other equipments. Even though support rod angular misalignment is a concern in isolation hangers, but they offer sufficient rubber bushings to prevent the rod from touching the housing. These spring hangers incorporate means of pre compression to minimize movement of the isolated equipment or system. These equipments are used in piping systems and other suspended equipment.

Open spring isolators consist of top and bottom load plates with adjustable bolts for leveling equipment. Springs are designed with a horizontal stiffness of at least 80% of the vertical stiffness that assure stability.

Restrained spring isolators are designed in a way to limit vertical as well as horizontal movement. They restrict movement and are used in equipment with large variations in mass like in boilers, chillers. Cooling towers and also used in outdoor equipment, such as condensing units and cooling towers, to prevent excessive movement due to wind loads.

Benefits of the isolation

• Isolation equipments offer high vibration and shock isolation to machines and equipments.
• They also offer good structural safety
•  Vibration shock and noise isolators reduce the machine operator fatigue and offer a safe working environment for the workers.
• Installation of these isolators reduces the potential of otherwise required regular maintenance.
• Isolation equipments extend the tool and machinery life.

We carry an extensive line of mounting and isolation equipments that are designed to effectively manage the vibration, noise and shock that can lead to a mechanical failure. The key to isolating vibration is to reduce its transmission to equipment or its supporting structure.

The rubber in mount acts as a spring with its own natural frequency, and this frequency depends to an extent on the stiffness of the spring.

But why is rubber an ideal material in this type of scenario?

Well the answer to this question lies in the basic knowledge of both natural and synthetic rubbers. Rubber is a synthetic or natural material whose long, coiled, high-molecular weight chains have been cross-bridged by certain chemical ingredients to form a network. It is characterized by the ability to accept and recover from extreme deformation of 200 percent or more. The term elastomeric includes natural rubber and the many synthetic materials that possess rubber-like properties.

With specific properties of rubbers makes it a versatile and useful material in almost every applications. Natural rubber in particular is especially useful as a spring material because of its longevity, resilience, low cost, resistance to a wide range of temperatures, and ability to bond to metals. Natural rubber is used in many of isolation Mounts because of these characteristics. Rubber has the ability to reduce transmission of vibration and noise in any mechanical equipment. It is resistant to the heat and chemicals encountered from within equipments. Also resistant to liquids and has the ability to withstand any conditions for many years.

When it comes to steel spring mounts, there is a linear relationship between the force and the deflection. However, in rubber springs they can be designed to provide different stiffness in non-linear directions. Shear forces such as friction occur when two opposite sides of the material experience forces in opposite direction. Rubber is a material that can be stretched much more than steel and hence forms a better isolation material for spring mounts.

Apart from these the advantage of rubber over steel is its ease of handling and installation, energy storage capacity, and ability to convert some energy to heat when it is deflected. Heat doesn’t build up in rubber as much as in other materials like metals. Unlike steel, rubber has some inherent damping ability that makes it a perfect isolation damping material. All the points given above makes it clear as to why rubber is valuable vibration isolator. However, it is important to take other factors into consideration before selection since a wrong mount can lead to amplifying of vibration. Hence, it is advisable to consider vibration control strategies in the product design process and consulting with an expert when selecting materials and mounts.

In most of the industrial machines there is a natural occurrence of vibration that is useful in most of the cases. However, vibration can cause major mechanical problems if not maintained to a certain frequency level. High level of vibrations can cause a machine or electronic equipment to make lots of noise and can also cause a machine to break down and stop working altogether. This is mainly why vibration dampeners are important in all fields of engineering.

So without getting too technical, let’s us first understand what vibrations is. Basically, a vibration is a back-and-forth type movement. Basically, when a particular machine part or an equipment resonant with certain frequencies; that is, when these frequencies are vibrating.  This leads to the machine cause their part or item to move dramatically leading to damage.

Mechanical and electronic equipment undergoes resonant frequencies, and so it is the job of an engineer to ensure that the natural frequency of these equipments is not the same as its resonant frequency. For instance, if the machine produces unnecessary high frequency vibration, it becomes essential to use vibration dampener to absorb the energy being transferred to various parts of machine. This ensures any kind of damages or break downs of machine and machine equipment.

There are a couple of different ways to solve the vibration problems. One way is to build a vibration isolation system around the machine or another way is setting a vibration damper to absorb the energy.

Basically, a vibration dampener is usually a visco-elastic substance which has the properties of both a solid and a liquid. This kind of substance helps absorb some of the energy from vibration, turning some of it into heat energy and storing some of it until the pressure is off. If a product simply can’t be engineered to take all resonant frequencies into account, vibration dampener are equipments that can absorb some of the vibration energy, essentially making the frequency lower and reducing wear and tear on an engine or electronic part and even reducing the chances of a potential break down.

In an industry, every mechanical equipment that constitutes any sort of moving part in it is bound to cause some sort of vibrations. This is mainly because moving parts creates huge amount of friction that ultimately releases energy in the form of heat and noise vibrations. These vibrations may at times be harmless, causing nothing but annoyance. But at times these vibrations could pose a great threat as well. Vibrations may at times cause major problems especially for a machine with moving parts. When this happens, engineers have to bring in various vibration control techniques to take care of the problem. Given below are some of the major reasons why vibration control is vital for an efficient performance of machine.

One of the major worries of vibrations is that it can cause malfunctioning of the machine parts. Every part in a machine has a resonant frequency. When these parts come into contact with a vibration of high frequency, it automatically starts to oscillate dramatically. Even the slightest of vibration in the right frequency can cause huge amount of movements in a machine. When the parts start to hit resonant frequencies, it moves a lot, ultimately leading to damaging the machine and machine parts. Over a period of time, this can cause more wear and tear of the moving parts of the machine. This can also lead to a machines break down and wear quickly, or it might cause certain parts of the machine to wear out frequently.

Besides the above mentioned issues, the fact that huge amount of vibration can be very annoying.  In case of a machine to be in contact with human beings, it would pose a great threat. It becomes very uncomfortable and also annoying to listen to the vibrations for the people working around it. In any type of machine or given equipment, things are become more comfortable when a good engineer brings vibration control techniques into the picture

When you think about vibration control, you might think about acoustical systems. These basically are used in controlling vibration. This is a great way to control vibration, but it isn’t the only best way. Depending on the source of the vibration and the type of machine in usage, engineers have to decide from several options in hand. There are a number of isolation pad and equipments and even dampers that are commonly used as isolation equipment. These equipments are very useful in engineering machines, as it can control sound noise and various other types of vibration.

Anti vibration mounts are classic dampening instruments used in a range of industrial machinery to reduce the high frequency noise & vibration that comes from these various units.  ANDRE HVAC is a specialist in manufacture and supplying of anti-vibration mounts, vibration isolation and shock absorption products & much more. The full range of anti vibration mounts includes vibration isolators, spring based mounts, enclosed and open spring mounts, shock mounts, rubber & metal AV mounts, rubber springs etc.

Here are some of types of anti vibration mounts & their applications

• Rubber in shear mounts

ANDRE HVAC manufactures high quality double deflection rubber in shear mounts of load range of 30 lbs to 2200 lbs in different sizes.  These Rubbers in Shear Mounts are used to absorb vibration & noise of applications like Fans, Fan Coil units, Fan Motor assembly of Air Handling units, Pumps etc. Made from high grade of Neoprene, the material offers excellent durability & is a classic resistant to Water, Weather, Ozone & Oil resistance

• Spring mounts

AHI manufactures a range of  spring mounts of Housed spring mounts for 1″ deflection, 2″ deflection, 3″ deflection, Open type spring mounts for 1″ & 2″ deflection, Spring mounts for Inertia base, Rubber cup spring mounts, Restrained Spring mounts for 1″, 2″ & 3″ deflection & so on. These spring mounts are constructed from premium quality heavy duty steel springs or cast iron housing. The application of these spring mounts are typically in fan, Air handling units, Pump & generators etc. Also restrained type of Spring Mounts is used in Chiller & Cooling towers as well.

• Seismic mounts

Seismic mounts are instruments used for absorbing vibration & restraints seismic forces for air handling units, centrifugal fans, pumps, chillers etc. These instruments are designed to withstand seismic forces of approximately 2G even at maximum rated load

• Shock mounts

Shock mounts are instruments used in a wide variety of applications to prevent unwanted noise & vibration. Made of rubber bushings & compressed in synthetic rubber rings on bolts provides it the much needed isolation. Shock mount are usually used in micro phones, disc drives & various automobile engines to dampen the vibration & noise.

Today, in any given mechanical industry, the main objective is to reduce vibration emission caused from within the machine & vibration caused to the machine due to the external force.  This is very important & plays a critical role in the operation of plant and machinery. With advanced technology & instrument, there has been a constant improvement in machinery performance. This has led to an increase in the speeds and efficiency of machines. Hence, it is very essential for efficient control of vibrations transmission & reduction.

The basic principle of vibration isolation

The objective of using vibration isolation devices in a machine is, for the reduction of pulsating vibrations. The objective is to keep the motion & the flexibly mounted machine within permissible limits for operation. For a vibration insulator to work efficiently, select the one that has sufficient dampening capacity & the one that is made of premium quality material.

Impact insulation

The physical properties of impacts are their duration, direction, magnitude & the frequency. The object of impact insulation is to change the forcing frequency consisting of a high vibration into an impulse of longer duration accompanied by small residual forces. Different from the normal vibrations, the system is provided with vibration isolation in the natural frequency of the insulated system that is not in accordance to its number of strokes. Thus, the residual forces that are transferred via the insulators become increasingly less, while the natural vibration period lasts longer.

What is vibration?

Vibration can be defined as the motion generated by any mass or force acting on that mass. Vibrations are not always bad. But if vibration frequency exceeds the required limit it can cause serious damages & can destroy a machine as well. These issues can be resolved in many ways through vibration isolation equipments.

Why isolate the vibration in HVAC & other mechanical system?

In every industrial or commercial setup there are a number of machines that can cause unwanted vibration. Common examples are fans, motors, chillers, and many more machines that cause abnormal vibration during its operation. Apart from being a nuisance, there are other repercussions of uncontrolled vibration levels.

Abnormal vibration of machines or equipment during their normal operations may result in:

• Loosening of the machine parts like bolts and screws
• High frequency vibration can cause disruption of sensitive parts of machinery that could ultimately lead to halt of the whole working process.
• Eventual damage to the machine or equipment could lead to inefficient operation of equipments
• This could result in production loss & in turn loss to the business.

Reason for cause of Vibration in mechanical equipments

• Unbalance:

This is basically in reference to the rotating machineries. Due to uneven distribution of mass in a rotating machine it could contribute to the unbalance that leads to vibration. This is one of the most common reasons for vibrations in mechanical equipment.

• Misalignment:

Misalignment is another major cause of vibration, particularly in machines that are driven by motors or any other objects in motion.

• Bent Shaft: A rotating shaft that is bent also produces vibrating effect since it losses it rotation capability.
• Gears in the machine: The gears in the machine always tend to produce vibration, mainly due to their meshing. The major things that tend to cause excessive vibration in gears are Misalignment of the gear axis, Gear teeth running out of contact and Wear and tear of gear tooth.

• Bearings:

This is a major contributor for vibration. In most of the cases the initial problem starts in the bearings and shifts on to the rest of the machine. A bearing devoid of lubrication tends to wear out fast and fails quickly, but before noticed, it damages the remaining components in the machine and would seem as though the other components had an issue.

Vibration damping is an important part of machines and industrial equipment. When machines and equipments that consist of a lot of moving parts, they would obviously be creating friction and definitely cause noise and vibration that needs to be controlled. Excess vibrations can create unnecessary noise; break down of machine or machine parts.

There are two ways of controlling vibration. One is through the simple method of absorption,   process also known as vibration damping. The other way is by limiting the level of vibration and noise frequency in a machine through vibration isolation tool.  Over the years there have been equipments designed to absorb and damp vibration from a variety of machines. Here are some of the options that are still available today:

Springs: springs are vibration isolation equipment that helps isolate vibration in a system. They basically absorb energy in, making vibration easier to control. Before considering springs, understand the requirement of the machine as they have limited applications and may actually break down over time.

Rubber: Rubbers are the best and the most common form of isolator to any vibration equipments. They absorb the energy and isolate any kind of vibration. Rubber materials can damp vibration a bit, but works better as an isolation equipment tool.

Pads or sheets of flexible materials: Materials such as elastomers, rubber, cork, dense foam and laminate materials form a perfect isolation material that helps limit the transmission of vibration. These materials are often used under heavy machinery, in common household items, in vehicles and even in higher frequency audio systems. Theses pads and flexible sheets can also be used in order to damp the amount of vibration and energy in an entire system.

Molded and bonded rubber and elastomeric isolators and mounts

These are often used as machinery mounts and also in vehicles. They absorb shock and attenuate some vibration.

Wire rope isolators

These isolators are durable and can withstand extreme environments. They are often used in military applications.

Base isolators for seismic isolation: Base isolators are made of layers of neoprene and steel with a low horizontal stiffness and are used in lower the natural frequency of the building. These base isolators are also designed to preventing the transfer of energy from the ground to the building.

Vibration suppression is the method or practice of using damping, isolation or cancellation equipments to reduce or eliminate the level of vibrations that otherwise occur and result in kind of loss in terms of its performance or limit or shorten the life span of a system. Tackling the vibration suppression is the most challenging problems in case of any mechanical and electronic equipment.  Often there are two common ways in which the vibrations from a machine are eliminated either via vibration isolation equipments or via vibration damping method.

Damping

One of the most common approaches to vibration suppression is by adding a vibration damping system or equipment. Vibration damping dissipates some amount of the vibration energy by transforming it to heat. By selecting the right vibration damping material you can suppress or eliminate noise and vibration in industrial, electronics applications caused by vibration and damaging resonance.

In case of a lightly damped system when the forcing frequency nears the natural frequency the amplitude of the vibration can get extremely high. This phenomenon is known as resonance and this is what we are trying to suppress. If resonance occurs in a mechanical system it can be very harmful and damaging that ultimately leads to eventual failure of the system.

Isolation

Isolation is another method of limiting vibration in equipment. Often vibration isolation is an effective means of vibration suppression used in many mechanical types of equipment.  These isolation equipments are used when there is a need to limit the vibration transmission from a vibrating structure to a sensitive component, or maybe even in case of limitation of noise transmission from a noisy component to the rest of the system. Through vibration isolation you can isolate an object or a piece of equipment, from vibrations that may be a source of the damaging the entire machine. A vibration isolator takes mechanical vibration energy out of the system and protects the system from any potential damages by suppressing vibration.

By selecting a right damper or isolation equipment, with proper implemented isolation material lowers the natural frequency of a system to below the high frequency level and eliminate the potential resonance. When you keep these frequencies within control, it will largely reduce the potential for vibration. Vibration and noise can potentially cause failure and even breakdown of machine completely. Hence it is very essential to use a good vibration isolation material to suppress vibrations.