Bruker AVANCE, User Manual

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Environment and Site Survey Measurement
H157655_1_008 43
7 Environment and Site Survey
Measurement
This chapter covers the various site survey topics related to the NMR laboratory. The
measurements and associated guidelines include:
• Vibrations
• Magnetic Environment
• Electromagnetic Interference: DC and AC EMF
• RF Interference
Note : The results of measurements carried-out during a site survey only reflect the specific
conditions that were present during the survey. Although these results are useful as a
reference, they would not be conclusive for the after-the-installation system performance if
one or more site conditions change. These changes may be related but not limited to
sources of vibrations and electromagnetic field and RF interference like electro-mechanical
equipment (HVAC, motors, pumps, freezers, etc.), elevators, car/bus/train traffic, power
lines, transformers, radio/TV stations and other possible RF sources.
7.1 Vibrations
External vibrations may cause field modulations in the sample cavity. This could result in
vibration sidebands, matched NMR signals that appear on either side of a main signal peak.
The effect of vibrations on NMR performance will depend on the type of work being carried
out, the type of system and the site building materials.
• Ideally the site should be at basement level, or on the ground floor (slap on grade), to
minimize building vibrations.
• Possible sources of vibrations are generators, compressors, fans, machinery etc.
Vibrations from external sources such as cars, trains, airplanes, and construction sites can
also cause problems.
• Measuring the extent of vibrations at the magnet location is a relatively simple matter; if
you suspect a problem you should contact your local Bruker office.
The following thresholds represent the maximum velocities and accelerations that could be
tolerated on the floor of the laboratory where the magnet is going to be located.