Minus K vibration isolation systems enable analytical balances
to operate in vibration environments not previously possible,
such as in manufacturing facilities with heavy equipment and
on upper floors of buildings.
Analytical balances are particularly sensitive to vibrations
because they introduce g-loads that interfere with the basic
weight measurement mechanism - the effect of gravity on a
mass. Vibrations reduce the resolutions and prevent the balances
from achieving their performance capabilities. High-resolution
balances with resolutions down to 1 or 0.1 microgram are particularly
sensitive to vibrations, even with the built-in electronic
averaging techniques used to compensate for vibrations. A
reduction of even one decimal place can seriously affect the
usefulness of balances for some research studies.
Low-frequency vibrations are particularly difficult to attenuate,
such as floor and ground vibrations caused by vehicles or
heavy equipment in manufacturing plants. Low-frequency vibrations
are also present in upper floors of buildings, particularly
horizontal vibrations caused by wind sway and vertical vibrations
from footfall or nearby equipment. Consequently, some metrology
labs have not been located in manufacturing facilities where
they would be most useful, and some laboratories on upper
floors of buildings have not been able to use high-resolution
balances to their maximum effectiveness.
Traditionally, vibration problems have been solved with “balance
tables” made from marble or other heavy material. These
balance tables reduce vibrations by adding mass and rigidity,
but they have limited effectiveness in high vibration environments.
Air tables have been used with limited success because they
are not effective against low-frequency vibrations and have
limited attenuation of typical ground and building vibrations.
Active or electronic force-cancellation systems have also
been used but these are very expensive and also have limited
dynamic range and cannot handle large amplitude vibrations.
Minus K vibration isolation platforms perform 10-100 times
better than air tables, depending on the vibration frequency,
and even better than active systems for a fraction of the
cost. They have been effective in allowing analytical balances
to operate in severe vibration environments and achieve improvements
in resolution of not just one, but in some cases, two and
three decimal places.