Environment and Site Survey Measurement
44 H157655_1_008
Figure7.1: Threshhold Values of Floor Acceleration
The thresholds listed above correspond to vibration related NMR sidebands reaching the
height of C
13
satellites in the CHCl
3
line shape spectrum. These thresholds might not meet the
needs for demanding NMR applications.
The height of vibration sidebands is approximately linear with the floor acceleration levels,
meaning that an NMR application requiring smaller sidebands than the height of C
13
satellites
would need to have reduced floor acceleration thresholds by the same percentage factor.
7.1.1 Integrated Isolator Options
All Bruker magnets are delivered standard with integrated isolators as follows:
• EMI (Elastomeric Isolators) – Standard for 300-500 MHz magnets.
• ADI (Air Spring and Damped Isolators) – Standard for 600 MHz magnets, optional for
300-500 MHz magnets.
• API (Air Piston Isolators) – Standard for 700-800 MHz magnets, optional for 300-600 MHz
magnets.
7.1.2 General Vibration Guidelines
General guidelines for buildings
The common standards for floor vibrations related to the impact on sensitive tools and
instruments are known as the VC curves and are presented below.
Criterion
Curve
Amplitude µm/s
(11µi/s)
*
Description of Use
Workshop (ISO) 800 (32 000) Distinctly perceptible vibration. Appropriate to
workshops and nonsensitive areas.
Office (ISO) 400 (16 000) Perceptible vibration. Appropriate to offices and
nonsensitive areas.
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