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.


Spring hangers for your piping, HVAC, and ceiling requirements

Ceiling hangers can comprise of spring elements, rubber elements or a combination of both. The use of spring hangers is recommended for locations subjected to impact and very low frequency noise. The hanger springs can provide lower natural frequencies than the designs that have rubber elements alone. When the two are combined the resulting anti-vibration hanger provides acoustic isolation across a wide frequency range.

The spring ceiling hanger consists of a metal bracket, spring with metal cup, and an elastomer element. The anti-vibration hanger can be suspended from a threaded rod that is properly anchored or can be attached directly to a metal or concrete deck. Normally the hanger springs are rated for a one inch Spring hangers for your piping, HVAC, and ceiling requirementsdeflection. The neoprene elastomer element is resilient enough to support one or more layers of the gypsum board that goes into the false ceiling. The spacer bracket which is a part of the spring ceiling hanger holds the vibration hanger rigidly till the gypsum board weight compresses the spring into position.

The metallic spring brackets that house the spring coil and the elastomeric element and made from metal strip bent into a near rectangular shape. They are protected from corrosion by the process of galvanizing or powder coating. Since the spring ceiling hangers are hidden from view, adequate corrosion protection is provided.

The high rise buildings also house the HVAC equipment, piping and ducting. While the HVAC equipment is mounted on the top of the buildings, the piping and ducting crisscrosses the various floors in the building. The designers try to hide the ductwork and piping between the concrete and gypsum ceilings. The problem that can arise is the vibrations carried by these HVAC ducts which can get transmitted to the supporting structures. This can create serious noise problems in the work areas inside the building. The solution lies in the use of HVAC hangers which can isolate the suspended piping or duct from the supporting structure. The deflection of the spring element combined with the resilience of the elastomeric element provides an effective dampening of vibrations.

The pipelines used in the industry, commercial and residential buildings are sometimes used to transport fluids at high temperatures. Since most of these pipes are metallic, they are prone to thermal expansion. If the rigid supports are provided, the pipes tend to deform when they carry the hot fluid. This can cause damage to the installed pipes. To take care of the thermal expansion and return to shape when the fluid temperature becomes normal, the use of pipe spring hangers is recommended. The spring element in the piping spring hangers can get stretched out or get compressed under the thermal movement of the pipe. The hangers provide for free displacement of the pipe in the vertical direction.

Andre HVAC International Inc. has been in the field of anti-vibration hangers and mounts for a good thirteen years now. They not only have the expertise in the field of pipe, ceiling, and HVAC hangers but also have a wide variety of the spring hangers in their manufacturing range.