Laboratory Infrastructure and Interactions
32
Site Planning Information BioSpec 70/30 USR_2_V020
Type of disturbance
Typical minimum
distance
DC/AC trains
40 m
Transformers > 1500 kVA
15 m
Transformers > 500 kVA
10 m
Transformers: > 100 kVA
6 m
electric lines: > 500 A
6 m
electric lines > 100 A
2 m
Table 5.5:
Disturbance in the vicinity
Countermeasure
The safest countermeasure is the avoidance of sources of disturbance in the immediate
vicinity of the magnet. If this cannot be avoided, countermeasures with in the building can
also be taken, e.g. by using an active shield (MACS) in the HF shielding cabin or by shielding
with soft-magnetic iron. Contact the planning office of your local Bruker BioSpin MRI branch.
5.3.2.2
RF interference
High-frequency disturbance can be produced among others by the following objects in the
vicinity of the MR instrument:
• Local transmitting stations for wireless analog or digital transmission of media or
telecommunications signals, e.g. digital television transmitters or mobile telephones.
• Computer processors
• Satellite systems
• Other MR instruments.
If the frequencies of transmission are in the range of the system's operating NMR
frequencies, massive disturbances with the operation of the system must be anticipated.
High-frequency interference is measured using a calibrated spectrum analyzers and a
calibrated antenna. The measuring equipment must have an accuracy of at least 5 dBµV/m
and the measurement must take place at the planned installation site.
The following table gives an overview of the various frequency ranges for commonly used
NMR nuclei. Every area must be scanned with a sweep width of <400 kHz and with sufficient
accumulation.
Magnetic flux density
19F-1H
X nuclei (15N-31P)
3.0 T
120 – 129 MHz
12 – 53 MHz
4.7 T
187 - 202 MHz
18 – 83 MHz
7.0 T
281 – 302 MHz
28 – 123 MHz
9.4 T
375 – 402 MHz
39 – 164 MHz
11.7 T
470 – 502 MHz
49 – 204 MHz
15.2 T
611 – 652 MHz
64 – 265 MHz
Table 5.6:
Frequency ranges for commonly used NMR nuclei
The following disturbance levels should be taken into account:
Summary of Contents for BioSpec 70/30 USR V2
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