Spring hanger isolators protect the support structure from vibration damage

Today, the buildings and structures are designed not only with architectural excellence but also with a lot more factors in consideration like the seismic constraints and vibration dynamics. In general, the people have also become aware of the damage caused by the vibrations. The designers take care of these aspects or make recommendations for vibration protection when they design a new product. The industries buying new machinery and equipment also install the right kind of anti-vibration mounts and isolators before they install the machines. The HVAC systems, piping and ducting also need to be isolated from the structure to prevent damage due to vibrations. Keeping this in mind a few vibration damping product details have been brought out here.

Hanger vibration isolators: Wherever the equipment is suspended from the ceiling or the support structure the hanger vibration isolators are used. These pipe vibration isolators are very simple in design with a metallic rectangular plate bracket that is either stamped or welded. Adequate corrosion resistance is provided through powder coating. The pipe spring hangers further consist of a deflection spring element, a spring cap and an elastomer element. The hanger vibration isolators are designed in such a manner that they can take a support rod misalignment of almost 30 degrees thus making the installation very flexible. The spring deflections are also available from 25 mm to 100 mm with load capacities in the range of 15 to 1500 Kg. The typical applications are pipe supports and hangers, ducting support and hangers, in-line fans and cabinet fans etc.

HVAC hangers: For applications requiring the Heating Ventilation and Air Conditioning (HVAC) equipment to be suspended from the ceiling or structural members, HVAC hangers are used. The HVAC hangers are very similar to the hanger vibration isolators described above with the difference coming in the deflection and load capacities. In the HVAC equipment, the dynamic forces also come into play when we suspend the equipment containing the rotating parts. The entire ducting for the HVAC systems is suspended using the ducting support and hangers. The heavier parts like the air conditioning unit, AHU etc. can be directly mounted on the rooftop using the air conditioning anti-vibration mounts.

Generator vibration isolator: There are two types of vibrations that occur within a generator system. One is the torsional vibration generated due to the engine combustion forces while the other is the linear vibration which can be due to many reasons. To tackle these linear vibrations, the engine and the alternator of the generator set are isolated from the base frame by using elastomeric engine mount vibration isolators. A number of elastomeric bushings are used for mounting the other electronic equipment and enclosures on the frame. The generator vibration isolators reduce the transmission of vibrations to the other components as the mechanical energy is dissipated in the elastomeric element. The equipment vibration isolation pads interrupt the energy transmission path between the rotating equipment and its surrounding support structure. The load capacity of the elastomeric isolators is limited as compared to the spring isolators. However, they are well suited for dampening low weight equipment on the generator set. The strength of the elastomeric isolators lies in their shear loading resistance when loaded in the vertical direction. The elastomeric generator vibration isolators not only resist misalignment forces but also dampen the high-frequency vibrations effectively.

Rear spring shackles: Shackles are commonly used in everyday life and you can easily observe the rear spring shackles in almost all four wheel automobiles. The shackles hold the rear leaf springs in position and together with it provides the damping action in the rear suspension of the vehicle. A typical rear shackle with vibration isolation is a product with metal to rubber bonding. The metal part is powder quoted for corrosion resistance. The elastomer prevents the metal to metal contact and hence, acts as a vibration isolator. The rear spring shackle also comes in an extended version in case there is such a requirement.

Andre HVAC International Inc. is a solution provider when it comes to fulfilling the anti-vibration needs of the clients. The AHI product range is very large and suits the multiplicity of the anti-vibration requirements raised by the clients. Whether you want to mount your equipment on the floor or on the rooftop, a huge variety of anti-vibration mounts are available depending on the load and deflections. Similarly, there are a number of anti-vibration suspension products like the equipment isolation spring hangers that can protect the surrounding structures from the ill effects of vibrations generated from suspended equipment.

Seismic isolation is important for protection against nature’s fury

Earthquake engineering for the design of base isolation has emerged as one of the strongest tools for control of structural vibration. When the potentially dangerous earthquakes occur, it is the seismic mountings for the vibration isolation that come into play and protect the building or non-building structure from damage. The importance of the seismic isolation devices and seismic mounts is not understood by the people till they see the devastation with their own eyes. However, the awareness about the subject and the media coverage of natural disasters has made the people cautious about seismic isolators.

Seismic base isolator: The methodology used in the past was to add braced frames and shear walls to strengthen the structure from the impact of the earthquake. This action was increasing the rigidity of the structure making it vulnerable to the seismic impact. The

Seismic base isolator

Seismic base isolator

seismic base isolator is a workable approach that isolates the structure from the ground below, reducing the propagation of seismic shock into the structure. Besides reducing the structural damage, the seismic isolation results in the protection of the other equipment like computers, precision instruments, medical devices, and communication hardware from damage.

Seismic isolation for HVACs: The seismic restraint guidelines must be followed for the installation of suspended piping, ductwork, conduits and cable trays. While the seismic HVAC isolation separation mounts are to be used for the heavier equipment like air conditioners, chillers, and AHUs, the adequate use of hanging spring isolators is recommended for the piping and ducting. It is also recommended to use transverse and longitudinal braces for the suspended piping and ducts. The seismic isolator manufacturer is likely to guide you for the seismic mounting hardware.

Seismic mounts: The ordinary vibration mounts provide vibration isolation. However, this feature is combined with a multi-directional flexible restraint to prevent the movement of equipment under the seismic forces in a seismic isolator. Thus, the movement of the equipment relative to the supporting structure is restricted. However, there is a limit to the restraint capacity along any major axis and is capped at 12 mm. Similarly, the seismic brackets for packaged units are standardized steel brackets with rubber grommet washers to minimize the impact of the seismic shock forces at anchor locations.

Isolation hangers: The hanger springs are designed to reduce the vibration and noise

Isolation hangers

Isolation hangers

generated by the hanging equipment. The isolation hanger consists of a stamped bracket with a spring, cap and elastomer element. The springs have lateral spring stiffness almost equal to the vertical stiffness. The hanger spring also allows for a support rod misalignment through a 30-degree arc. The major applications for the isolation hangers are the isolation hanger duct and isolation hanger acoustic ceiling.

Among the seismic isolator manufacturers, Andre HVAC International Inc. has taken the lead in the product variety and availability of the seismic isolation units. Whether it is the seismic bracket or the HVAC vibration hangers you are likely to find the complete seismic solution at AHI.