Many forms of precision equipment, such as equipment used in the semiconductor manufacturing, nanotechnology, electron beams, and optics, require low levels of ground vibration for proper use. Vibrations from footfall, vehicle pass-by on exterior roads, construction, aircraft, local railroads, facilities, wind, or even air pressure can all induce vibrations in a building’s structure. In these precision applications the smallest ground-borne vibrations may cause errors and be costly.
Typical measurements are compared to tolerance limits defined by standards including BBN curves, IEST VC curves, and ASHRAE curves. These curves have are a series of curves that range in strictness based on the equipment type from surgical suites on the low end to nanotechnology applications on the high end.
The comparison measurements are often done in frequency spectra based third octave bands of velocity data. SignalCalc analyzers allow users to very easily acquire high-accuracy velocity data or acceleration data, convert acceleration to velocity, and display the frequency data in proportional band (1/3 octave) displays.
On the other side, manufacturers or operators can also use dynamic signal analyzers to determine the broad band response limits that equipment operates to when setting specific vibration level specifications. The use of small electrodynamic shakers, such as SignalForce Electrodynamic Shakers, and a dynamic signal analyzer can allow the study of performance versus frequency and level rather easily.
In doing such low level measurements, it is important to select measurement equipment with enough resolution to be able to accurately record low level signals. Proper sensor selection is critical. Additionally, using a Dynamic Signal Analyzer that has a high dynamic range is also critical to the measurement quality. With 120 dB or better dynamic range, SignalCalc Dynamic Signal Analyzers are well suited for low level applications.