Vicoda-Lisega Anti-vibration mounts

Spring anti-vibration mounts are used to isolate mechanical vibration in power plants on equipment such as turbines, pumps, blowers, coal mills, etc., or large machines such as presses, forging hammers, crushers and the like.

Lisega now offers these elements widely used in industry and construction. It is important to clarify that in mechanical vibrations there are two types of solutions, passive and active. Within the passive ones, Vicoda offers three types of solutions, one is to isolate, another is to dampen and the most sophisticated is to absorb.

Isolation is a passive method of vibration control, it is based on cutting the transmission of energy from the vibration source (exciter) to the oscillating system. Thanks to the reduction of energy transmission, the oscillating system will vibrate with a lower amplitude than the non-isolated system.

Damping is another passive method that consists of removing, by means of a damping element, the energy of an oscillating system. Unlike isolation, this procedure starts by transferring energy from the exciter to the oscillating system. Part of this vibrational energy is transformed within the damping element into another form of energy.

Absorbing can be a passive or active method, which consists of having a second oscillating system that is coupled to the original system. If an absorber is chosen with the right characteristics, i.e. with the right mass, damping parameter and elastic properties, it will be able to absorb oscillatory energy from the original system. The absorber will oscillate and the vibration of the original system will be significantly reduced.

Why Vicoda?

Springs are the essential elements of a Vicoda anti-vibration base, but the firm has now been acquired and incorporated into Lisega, a world leader in pipe support systems. This means that Vicoda benefits from more than 50 years of experience in the design and manufacture of spring-based variable and constant load mounts.

The stiffness of conventional coil springs suffers over time, particularly if exposed to high loads and high temperatures (relaxation). To counteract the negative effects of this common phenomenon, Vicoda uses pre-relaxed springs, which guarantee constant functionability throughout the service life of the anti-vibration base.

Spring mounts; small vibration isolators

VICODA® spring mounts are an excellent solution to isolate the vibration induced by the equipment or the source of the vibration. By isolating, they do not allow energy to be transmitted from the vibration source (exciter) to the oscillating system, which can be the floor or civil and/or mechanical structures connected to the system.

These bases cover low frequencies between 2.5 and 5 Hz. All spring anti-vibration mounts can be additionally equipped with viscoelastic dampers to not only isolate but also damp mechanical vibration.

VICODA® spring mounts are designed as follows:

• Each series has the same installation height.
• Large load range between 90 and 72, 200N (9 and 7362 kgf).
• Frequencies of 2.5Hz.
• Pressure and shape locking height adjustment (also available in optional stainless steel).
• High quality corrosion protection (CDP coated springs).
• CRD type damping using the same dimensions (optional).
• Structural noise damping (optional).
• Lifting device (optional).

Application Fields

VICODA® spring anti-vibration mounts are suitable for use in a variety of applications. They provide the best solution for vibration and structure-borne noise isolation, for example in:

• Fans or Ventilation systems.
• Air conditioning systems.
• Pumps or pumping systems.
• Electronic equipment.
• Measuring equipment.
• Small and medium power presses.

Available models

Required Information for correct selection

To calculate the dimensions, number of vibration isolation mounts and type, the following information is required:

• Type of system / equipment requiring vibration isolated installation.
• Total weight of the system / equipment or individual weight of components in kN.
• Drawing of the equipment base.
• Center of gravity of the system / equipment or individual centers of gravity of the components (If not available, we will assume a central center of gravity).
• Excitation frequency or rotational speed in Hz or rotations / min.
• Desired insulation efficiency.
• Indoor or outdoor installation.

Applications

Spring anti-vibration mounts for concrete foundations, isolators and/or dampers

Spring anti-vibration mounts are the products commonly used to decouple and isolate an oscillating system from the vibration source. Mounted between the source and the system, they minimize the transmission of energy from the source to the system.

VICODA® spring anti-vibration mounts are effectively used for vibration isolation of heavy machinery bedplates, such as presses or hammers, in power plants, coal mills, diesel power units, turbine systems, feedwater pumps, condensers, etc. They provide support for static loads and reduce the transmission of dynamic loads to the foundation.

VICODA® spring anti-vibration mounts generally consist of three main parts: an upper and lower housing, coil springs and a viscoelastic damper. The frequency covered by the anti-vibration mounts is between 2 and 7 Hz.

Design

VICODA® spring anti-vibration mounts are used effectively to isolate vibration in concrete foundations supporting rotating equipment such as turbines, feedwater pumps, etc. They provide support of static loads and reduce the transmission of dynamic loads to the foundation.

An important feature of these anti-vibration bases is that they can be locked at a predetermined load (preload). The preloaded spring elements are installed in an enclosed location (thus they would work as rigid supports); at the end of the installation, which may be the installation of heavy machinery, the spring elements will be activated by unlocking them. Thereafter the devices act as vibration control elements.

Product range

The VICODA® product portfolio covers most of the typical base isolation applications in power plants as well as for mounting capacitors. By combining a set of VICODA® spring anti-vibration mounts in one application, an optimal configuration can be achieved.

VICODA® spring elements can come with or without additional damping elements. The capacity for bases without damping element is 126 kN (12,848 kgf) up to 2096 kN (213,732 kgf) and with damping loads up to 1300 kN (132,563 kgf).

Fields of application

• Turbine / turbine foundation.
• Coal mill foundations.
• Fan / blower foundations.
• Condenser foundations.

Parameters and construction

The basic parameters necessary for the definition of a foundation isolation solution with spring anti-vibration foundations are:

• Load [kN], determined by the weight of the supported machine and the load distribution.
• Natural frequency of the foundation.
• The main excitation frequencies [Hz] of the vibrating source.
• Operating temperatures [°C] in case of damping elements.
• Installation dimensions [mm] and geometrical limitations.

The installation of machines with vibration isolation greatly reduces the transmission of dynamic loads between the machine and the base. Source isolation reduces vibrations of crushers and presses.

Generally, spring elements have very limited damping qualities, based on the low natural damping of steel; base performance can be improved by integrating viscoelastic damping elements into the bases.

Even if the vibration source goes through different operating states, with varying excitation frequencies, e.g. when starting a turbine, damping elements are needed for vibration control. From its resting state (0 Hz), the turbine is accelerated to its operating frequency. Since effective isolation by means of spring anti-vibration mounts is designed in such a way that the oscillating system has an eigenfrequency Fo, which is well below the permanent excitation frequency Fr, i.e. the operating frequency, after starting the turbine it will necessarily pass through this resonance zone; to avoid an increase in vibration in this zone, the system must be equipped with safety damping elements.

Advantages

• Wide load range: 1 kN (224.81 lbf) to 2,700 kN (606,984.15 lbf).
• Operational stability according to EC 3.
• Low natural frequency (1 Hz to 8 Hz) of the system and therefore maximum isolation.
• Horizontal spring rates from 20% to 130% of vertical spring rate.
• Presettable and lockable so that a replacement is always available.
• Surface coatings for corrosion categories up to C5 according to DIN EN ISO 12944.
• Individual damping factor with integrated dampers as required.

Viscoelastic Dampers (Dampers)

Application Areas

Viscoelastic dampers are equipment that reduce mechanical vibration in all directions produced by rotating equipment. They effectively reduce vibrations by converting kinetic energy into heat, damping the motion of the system. Their design allows them to be used in a wide range of applications, however, the required type of viscoelastic damper depends on the planned application.

They can be used in almost all industrial sectors to reduce resonant vibrations. Applications include power production, process engineering and damping of individual machines or complete piping systems. Dampers can be used to solve vibration problems as long as there is an external structure or floor that offers the highest possible stiffness.

Ambient temperatures from -30 (-22 ° F) to + 110 ° C (230 ° F) as well as extremely demanding environmental conditions (e.g. chemicals, dust or salt-laden atmospheres) are no obstacle here. Viscoelastic dampers solve vibration problems in equipment assemblies, in individual machines or complete piping systems. They can be mounted in demanding ambient conditions and when attached to a piping system that transfers high temperature to them, the viscoelastic damper can be equipped with special isolation.

All viscoelastic dampers and damping parameters are tested and monitored by our in-house testing laboratory. If required, they can be certified by external testing laboratories in accordance with the KTA 3205 Safety Standard.

Design

Viscoelastic dampers consist of a metal housing filled with a highly viscous liquid and a piston connected to the upper connection plate, which can move freely in all directions within the medium. Either the upper or the lower connection plate of the damper can be connected to the vibrating system, while the other plate is mounted on a fixed pillar.

The dampers cannot withstand static loads and are protected against corrosion as standard according to ISO 12944 C3 (M).

Models

Viscoelastic shock absorber type VD.

Damping fluid: High viscoelastic bitumen.

Suitable for applications up to 554 kNs/m and frequencies up to 5 Hz.

Operating temperatures from +20 °C to +80 °C.

Viscoelastic cushioning type VM.

Damping fluid: High viscoelastic polybutane.

Suitable for applications up to 438 kNs/m and frequencies up to 5 Hz.

Operating temperatures from -10 °C to +40 °C.

Viscoelastic shock absorber type VI.

Damping fluid: High viscoelastic silicone oil.

Suitable for low commitment applications.

Operating temperatures from -30 °C to +110 °C.

Applications