It is usually advisable to mount the machine on vibration isolators, particularly if lowfrequency
noise is the main problem. This ensures that little energy is transmitted to the floor.
If this is not done there is the possibility that the floor surrounding the enclosure will re-radiate
the energy into the surrounding space, or that the enclosure will be mechanically excited by the
vibrating floor and act as a noise source. Sometimes it is not possible to mount the machine on
vibration isolators. In this case, excitation of the enclosure can be avoided by mounting the
enclosure itself on vibration isolators, while at the same time avoiding an air gap at the base of
the enclosure by using heavy rubber flaps. Note that great care is necessary, when designing
machinery vibration isolators, to ensure that the machine will be stable and that its operation will
not be affected adversely. For example, if a machine must pass through a system resonance
when running up to speed, then "snubbers" (which are usually horizontally mounted flexible
elements) can be used to prevent excessive motion of the machine on its isolation mounts.