Theory

Technical Overview

Vibrations limit the perfomance of sensitive instruments and occur at varying levels in most environments. The reduction
in levels of vibrations will improve the performance of expensive equipment leading to savings in cost and improvements in
efficiency. Thus the need to remove vibrations to optimise performance has become crucial. The mechanics of isolating
out vibrations is well understood and different levels of isolation can be obtained according to the types of isolators used. The
simplest isolators are made from rubber and provide some isolation, but are much less effective then air isolators or active types.
We make a wide range of isolators at different levels of performance to suit most needs and budgets. We have spent many years
developing unique products that have been tested and are recommended by leading manufacturers thoughout the industry. Our
products are available in a wide range of shapes and sizes to support loads of varying weights and footprints. We also supply
products for use in stringent environments such as Class 1 cleanrooms and in Biohazard areas.

Theory

In simplest terms the elimination of movements from a surface is acheived by having a load which is separated
from the support surface (often the floor) by a damped spring such that when the floor moves the spring damper
combination removes the energy being transmitted, often converting it into heat. The larger the load the smaller
the movement causes by an energy input and the more effective the spring damper the better the isolation. As well
as mass, the stiffness of the spring and the level of damping will determine the level of isolation.

The major source of vibrations are usually from building floor or walls and both vertical and horizontal. These
vibrations arise from many sources; road traffic, trains, large machinery, fans, lifts, people traffic and building
resonances and sway. However, in general cyclical vibrations tend to occur from 7Hz with the exception of building
sway at levels over 3 floors.

Isolators have natural resonant frequencies which are usually specified, as they will only start to become effective
at isolation at several times this frequency. So to effectively isolate out building vibrations, isolators should have
a natural frequency around 2Hz. This cannot be achieved using a rubber or elastomeric isolator but is well within
the capabilities of an air isolator. Elastomeric isolators are good are dealing with vibrations from rotating machinery
and provide a low cost solution to this source of vibration problems.

It is also important that the surface on which an instrument is placed does not itself cause vibrations. This is achieved by
ensuring it is rigid and that surface borne vibrations are soaked away using a layered sound deadened construction. Simple
steel or granite blocks will resonate with a broad range of frequencies if disturbed but the use of a dampning layer which soaks away
vibrations will effectively remove them.

We design and manufacture a range of air isolators and low cost Sorbothane elastomeric isolator products. Our air isolators are based on
proven rolling diaphragm designs, which were originally developed in the photonics industry. An air isolator has a low natural frequency,
which depends on factors such as the height of the isolator air column and the ratio of the piston area to the air volume. We offer a range
of isolators to suit loads from 50kg up to 500kgs with resonant frequencies as low as 1.1Hz. Our Sorbothane isolators are designed to have
resonant frequencies as low as 7Hz.

Our air isolators are all connected by tuned restrictors to damping volumes. This ensures that the large movements caused by major disturbances are
rapidly damped away. Without damping volumes, oscillations will continue for long periods as in the case of a simple spring mechanism. The
dmaping volumes have the effect of making our air isolators feel stiff to the touch. When major moves occur air is forced out of the isolator section
into the damping chamber and then slowly drawn back in. For higher frequencies the isolator is unaffected by the damping chamber and isolates
according to its design, so at frequencies several times above the natural resonance vibrations are isolated away.

Our elastomeric isolators use Sorbothane, which is a self-damped elastomer which greatly outperforms simple rubber or neoprene. Again it damps away major
disturbances far more effectively and through proper design can be used ot make isolators with resonant frequencies as low as 7Hz.