Much equipment used in nanotech, physical and biological sciences can’t function properly if subjected to
vibrations that exceed small threshold values.
As a result, lab designers are faced with the
challenge of developing designs where vibration disturbances are within acceptable limits
to further science.
With the high costs and technical difficulties associated with the design of high-tech
facilities and labs, potential disturbances must
be discussed early in the design process. Implementation of vibration control measures must
be well-planned and verified as the design and
construction process progresses, and electromagnetics specialists are critical to this success.
The effectiveness of a vibration control solution is governed by the laws of physics. And,
while physics hasn’t changed, isolation requirements have. Modern lab equipment is becoming more sensitive, placing tighter constraints
on allowable levels of vibration.
“Fifteen years ago it was possible to design
an affordable building floor that was sufficient-
ly stiff to accommodate all lab equipment in the
building,” says Jeffrey Zapfe, President, Acen-
tech. “It’s simply not possible to do that now;
equipment vibration limits are too restrictive.”
The current trend to accommodate this
equipment is to design local “low-vibration”
islands within a building, which incorporate
some form of isolation system to protect the
The costs of amending a building design to
accommodate stringent vibration criteria is
proportional—the higher the floorplate above
grade, the greater the cost to achieve the criteria. “Given this, vibration-sensitive equipment
and research functions are driven down to
lower levels in buildings to better spend available funds,” says Mark Tinsley, LEED AP, Associate, Lord Aeck Sargent.
However, increasingly architects and engineers are tasked with integrating vibration-sensitive equipment and research functions on
upper floors. To address this trend, designers
rely on point-of-use solutions, such as air
tables, which require the end-users to provide
their own, process-driven solutions.
Yet, vibration control isn’t just about
vibration sensitivity. Some equipment can be
adversely affected by acoustic noise. As a result,
effective acoustic enclosures and low-noise
HVAC systems can be important in the design
process, according to Zapfe.
The importance of site
Site selection is one of the most important
factors in designing a low-vibration lab or building. The baseline level at the foundation is largely determined by the environmental vibrations
at the site. These sources of vibrations include
ambient microseismic activity, street and rail
traffic, aircraft overflights, machinery operating
nearby and construction work.
Site planning involves disturbances from
within the building—elevators, vehicles, MEP
systems—and outside the building—Earth’s
natural magnetic flux. “Importantly, shielded,
or unshielded, tools can ‘feel’ interference
from a host of sources, such as wireless networks and variable-frequency drives, as well
as negatively impact other components within
or outside the building,” says Davidson Scott,
Director of Engineering, Novus Environmental Inc., Ontario, Canada. As a result, lab
planners must consider siting the tool area—
gaining distance from a potential source—as
well as the various strategies to defeat or lessen
the EM field—traditional shielding.
Selecting an inherently quiet site for a facility
with critical vibration requirements is a primary consideration, particularly in regard to those
sources beyond the control of a facility developer or designer.
Some of the most common in-facility sources of vibration are generated from staff walking,
interior dollies or vehicles such as forklifts.
However, significant vibration can also be generated by the facility’s equipment—such as vacuum pumps, materials handling systems and
production tools such as scanners and robots.
These disturbances can be addressed in the
layout and planning of the facility, with strat-
egies that locate sensitive equipment far away
from internal and external sources of vibration.
As a rule of thumb, elevators, fans, cooling
towers, compressors and other heavy electrical
equipment should be situated in areas that
are well-separated from those where sensitive
equipment is located.
Vibration on ground-supported slabs is
less severe than higher floors, so it’s wise to
reserve the on-ground floor for sensitive
equipment and/or critical labs. If the sensitive
equipment is planned for implementation on
a higher floor, it should be placed near cores
or columns or atop heavy girders, where supported floors tend to vibrate less than near
the middle of structural bays.
Effective vibration control design
Vibration and shielding controls are often
associated with core lab spaces—the spaces at
the heart of a given facility. These spaces must
be functional to ensure work can be conducted free from the confounding effects of
vibrations and electromagnetic fields. In the
end, high-quality research yields top-notch
“In most facilities we work on there’s
a desire to design flexible spaces that can
accommodate future evolutions in research
and tool technology,” says Brad Pridham,
Vibration Specialist, Novus Environmental
Inc. “In such cases, control strategies must
target not only the receiver space, but also the
source spaces (service spaces, loading bays)
and transmission paths (shielding of feeder
line, structural members).” The details associated with these strategies impact many facets
of the base building design and require careful
integration. And successful integration results
in lab spaces adaptive to future science needs.
Proper vibration/EMI control in lab environments furthers research
by isolating state-of-the-art vibration-sensitive equipment.
NMR at the Institute of Imaging Science at Vanderbilt Univ. Image: Aerial Innovations Inc.