Bruker BioSpin NMR Fourier 300 Technical manual

Version
Innovation with Integrity
Fourier
003
Site Planning
User Manual
NMR

Copyright © by Bruker Corporation
All rights reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted, in
any form, or by any means without the prior consent of the
publisher. Product names used are trademarks or
registered trademarks of their respective holders.
This manual was written by
Peter Ziegler
© March 26, 2012: Bruker Corporation
Billerica, Massachusetts, USA
P/N: B127527
DWG-Nr.: B3M4746B

3
B127527_00_03
Table of Contents
Content
1 Introduction....................................................................................................5
1.1 Units Used Within This Manual ................................................................................ 5
2 Safety..............................................................................................................7
2.1 Introduction............................................................................................................... 7
2.2 Magnetic Safety........................................................................................................ 7
2.3 Cryogenic Safety...................................................................................................... 7
2.3.1 What is a Quench?................................................................................................... 8
2.4 Emergency Planning................................................................................................ 8
2.5 Fire Department Notification..................................................................................... 8
2.6 Earthquake Safety.................................................................................................... 9
2.7 Country-specific Safety Regulations ........................................................................ 9
3 Magnet Access and Rigging.......................................................................11
3.1 Introduction............................................................................................................. 11
3.2 Considerations for Off-loading on Site ................................................................... 11
3.2.1 Delivery Area.......................................................................................................... 11
3.2.2 Transport Weight.................................................................................................... 11
3.2.3 Equipment Requirements....................................................................................... 12
3.3 Considerations for Transport to the NMR Room.................................................... 12
3.3.1 Accessibility to the NMR Room.............................................................................. 12
3.3.2 Equipment Requirements....................................................................................... 12
3.4 Considerations for Assembling the Magnet............................................................ 12
3.4.1 General Requirements........................................................................................... 12
3.4.2 Equipment Requirements....................................................................................... 13
3.5 Checklist for Magnet Access and Rigging.............................................................. 13
4 Lab Requirements .......................................................................................15
4.1 Room Layout.......................................................................................................... 15
4.2 Ceiling Height......................................................................................................... 15
4.2.1 Checklist for Ceiling Height Requirements............................................................. 16
4.3 Footprint................................................................................................................. 16
4.4 Minimum Floor Capacity......................................................................................... 16
4.5 Floor Types ............................................................................................................ 17
4.6 Vibration Isolation................................................................................................... 17
4.6.1 Sources of Vibrations............................................................................................. 17
4.7 Electromagnetic Interference ................................................................................. 17
4.7.1 DC Interference...................................................................................................... 18
4.7.1.1 Measuring DC Fluctuating Fields........................................................................... 18
4.7.1.2 Reducing DC Interference...................................................................................... 18
4.7.1.3 Guidelines: DC Interference................................................................................... 18
4.7.2 16-2/3 Hz and 50/60 Hz Interference..................................................................... 19

4B127527_00_03
Table of Contents
4.7.2.1 Measuring 16-2/3 Hz and 50/60 Hz Fluctuating Fields...........................................19
4.7.2.2 Reducing 16-2/3 Hz and 50/60 Hz Interference.....................................................20
4.7.2.3 Guidelines: 16-2/3 Hz and 50/60 Hz Interference ..................................................20
4.7.3 RF Interference.......................................................................................................20
4.7.3.1 Measuring RF Fluctuating Fields............................................................................20
4.7.3.2 Reducing RF Interference ......................................................................................21
4.7.3.3 Guidelines: RF Interference....................................................................................21
4.7.4 Checklist for EMF Interference...............................................................................22
4.8 Utilities....................................................................................................................22
4.8.1 Electrical Power Requirement................................................................................22
4.8.1.1 General Power Requirements................................................................................22
4.8.1.2 Other Power Requirement Consideration...............................................................22
4.8.2 Checklist for Power Requirements.........................................................................23
4.9 Compressed Gas Requirements............................................................................23
4.9.0.1 General Gas Requirements....................................................................................23
4.9.0.2 Gas Requirements for Accessories........................................................................23
4.9.0.3 Compressed Gas Specifications ............................................................................23
4.9.1 Checklist for Utility Requirements...........................................................................24
5 Installation....................................................................................................25
5.1 Overview.................................................................................................................25
5.2 Installation Procedures...........................................................................................25
5.2.1 Magnet Assembly...................................................................................................25
5.2.2 Magnet Evacuation and Flushing with Nitrogen Gas..............................................25
5.2.3 Cooling the Magnet to Liquid Nitrogen Temperatures............................................26
5.2.4 Cooling the Magnet to Liquid Helium Temperatures..............................................26
5.2.5 Charging the Magnet..............................................................................................26
5.3 Checklist of Installation Requirements ...................................................................27
6 Contact.........................................................................................................29

5
B127527_00_03
1 Introduction
This manual contains information about site planning and preparation prior to delivery of
a Bruker BioSpin Fourier system. The manual should be read through carefully as
mistakes made initially may be costly to remedy at a later stage.
The system covered by this manual is for a Fourier spectrometer at 300 MHz.
The chapters in this manual deal with various points that need to be considered for suc-
cessful system operation. They have been included to familiarize you with general
principles of successful site planning.
Appendix A contains an example sample room layout for a Fourier 300 MHz system.
For specific questions that may not be addressed in this manual, or for further
information on a topic, do not hesitate to contact your local Bruker BioSpin office.
NOTE: Site planning is not only relevant for the installation of a new system, rather also
by any changes in the equipment or devices, and by any renovations or room changes!
1.1 Units Used Within This Manual
The SI Unit Tesla (mT) is used throughout this manual whenever magnetic field
strengths are discussed. Some readers may however be more familiar with the Gauss
(G) Unit.
Likewise the unit kilowatt is used for the measure of heat energy (e.g. amount of heat
generated by a device per hour). Some readers may be more familiar with these mea-
surements in BTU/hour.
Wherever possible both the metric and U.S. Standard measure units have been used
throughout this manual. When compared to metric measurements, the U.S. Standard
measurement units are often indicated by „in USA“. This does not mean that the
measurements are only limited to the United States, but rather are for all countries in
North America and South America that use the U.S. Standard System.
In most cases the weights and measures have been rounded upwards where necessary.
The following table offers the common metric to U.S. conversion factors used in this
manual:

6B127527_00_03
Introduction
Table 1.1: Conversion table for units used in this manual
Measure SI Units U.S Standard Units Conversion Factor
(rounded to nearest
hundredth)
Linear meter (m)
centimeter (cm) feet (ft.) inch (in.) 1 m = 3.28 ft. 1 m = 39.37 in.
1 cm = 0.394 in.
Distance kilometer (km) mile (mi) 1 km = 0.62 mi
Area square meter (m2) square foot (ft2)1m
2= 10.76 ft2
Volume cubic meter (m3)
liter (l) cubic foot (ft3) quart (qt) 1 m3= 35.32 ft3
1 l = 1.06qt (liquid)
Weight kilogram (kg) pounds (lbs.) 1 kg = 2.21 lbs.
Preasure bar pounds/square inch (psi)
atmosphere (ATM) 1 bar = 14.51 psi 1 bar = 0.99 ATM (standard)
Flow (e.g. gas flow cubic meter/minute (m3/min. cubic feet/minute (ft3/min.) 1 m3/min. = 35.32 ft3/min.
Temperature 0C0F F = C x 1.8 + 32
0F0C C = (F - 32) / 1.8
0C K K = C + 273.15
K0C C = K - 273.15
0F K K = (F + 459.67) / 1.8
K0F F = K x 1.8 - 459.67
Magnet Field Strength Tesla (T) Gauss (G) 1 T = 104G
Heat Energy BTU/hour kW 1 BTU/hour = 0.000293 kW
(BTU = British Thermal Unit which is the required heat to raise 1 pound of H2O by 1 degree Fahrenheit)
SI = International System of Units

7
B127527_00_03
2 Safety
2.1 Introduction
In terms of safety the presence of a relatively strong magnet is what differentiates NMR
spectrometers from most other laboratory equipment. When designing an NMR
laboratory, or training personnel who will work in or around the laboratory, no other
feature is of greater significance. As long as correct procedures are adhered to, working
in the vicinity of superconductive magnets is completely safe and has no known harmful
medical side effects. Negligence however can result in serious accidents. It is important
that people working in the vicinity of the magnet fully understand the potential hazards.
Of critical importance is that people fitted with cardiac pacemakers or metallic implants
should never be allowed near the magnet.
The magnet is potentially hazardous due to:
• The large attractive force it exerts on ferromagnetic objects.
• The large content of liquid Nitrogen and Helium.
2.2 Magnetic Safety
A Magnetic Field surrounds the magnet in all directions. This field (known as the stray
field) is invisible, hence the need to post warning signs at appropriate locations. Objects
made of ferromagnetic materials, e.g. iron, steel etc. will be attracted to the magnet. If a
ferromagnetic object is brought too close, it may suddenly be drawn into the magnet with
surprising force. This may damage the magnet, or cause personal injury to anybody in
the way!
The Fourier 300 super conducting magnet is actively shielded. The following must be
understood when working with such a shielded magnet.
• The active shielding of the super conducting coil reduces the stray magnetic field
and therefore its effect. The 5 Gauss line in the horizontal direction extends
26.5 cm around the outside of the magnet. In the vertical direction it extends about
24 cm out of the can at the middle but it does not go above the helium stacks or
below the floor.
• In spite of the active shielding, the stray magnetic field immediately adjacent to the
bore of the magnet is very high and the attractive forces on ferromagnetic objects
are very strong!
2.3 Cryogenic Safety
The magnet contains relatively large quantities of liquid helium and nitrogen. These
liquids, referred to as cryogens, serve to keep the magnet core at a very low
temperature.
Because of the very low temperatures involved, gloves, a long sleeved shirt or lab
coat and safety goggles should always be worn when handling cryogens. Direct

8B127527_00_03
Safety
contact with these liquids can cause frostbite. The system manager should regularly
check and make sure that evaporating gases are free to escape from the magnet, i.e.
the release valves must not be blocked. Do not attempt to refill the magnet with helium
or nitrogen unless you have been trained in the correct procedure.
2.3.1 What is a Quench?
A magnet quench is the spontaneous breakdown of superconductivity in a partially or
fully energized magnet. The stored field energy is transformed into heat, leading to a fast
evaporation of liquid helium. During a quench, an extremely large quantity ,~40 m3
(1,400 ft3) of helium gas is produced within a short time.
Helium and nitrogen are non-toxic gases. However, because of a possible magnet
quench, where upon the room may suddenly fill with evaporated gases causing
potential danger of suffocation. Adequate ventilation must always be provided and it is
recommended that any person should leave the room.
2.4 Emergency Planning
Due to the strong magnetic fields and presence of cryogens when using NMR systems,
it is important to define and communicate what to do in case of problems or an
emergency. An Emergency Plan can be defined as a documented set of instructions on
what to do if something goes wrong. Emergency Plans are often defined as part of the
Standard Operating Procedures (SOP), or as a stand-alone document. In any case
every NMR laboratory should have an Emergency Plan in effect in case of problems or
emergencies.
As every organization has its own policies and procedures, as well as varying laboratory
layouts, an Emergency Plan should be individually defined for each laboratory as
appropriate. Upon request Bruker can provide useful information on emergency
planning.
2.5 Fire Department Notification
It is recommended that the magnet operator introduce the fire department and/or
local authorities to the magnet site. It is important that these organizations be
informed of the potential risks of the magnet system, i.e. that much of the
magnetic rescue equipment (oxygen-cylinders, fire extinguishers, axes etc.) can
be hazardous close to the magnet system. On the other side, their expertise and
experience can be invaluable in creating an Emergency plan.
• Within a NMR laboratory CO2 magnetic fire extinguishers must NOT be used.
Breathing equipment which uses oxygen tanks made out of magnetic material can
be life threatening when used close to a magnet system which still has a magnetic
field present.
• Helium gas escaping from the system must not be mistaken for smoke. Instruct the
fire department and technical service not to extinguish the magnet system with
water. The outlet valves could freeze over and generate excess pressure within the
system.

9
B127527_00_03
Safety
• NMR laboratory windows which are accessible during an emergency must be
clearly marked with warning signs, visible from the outside.
2.6 Earthquake Safety
In regions where there is a potential risk of earthquakes, additional measures must be
taken to reduce the chance of personal or property damage through movement or
tipping of the magnet.
Many countries or regions have documented regulations, including building codes,
regarding earthquakes. Before installing a magnet system, it is highly advisable that you
check with local authorities on whether your area is prone to earthquakes and if there
are any regulations in effect.
If your area is regarded as an earthquake area there are several shock absorbing
measures or riggings available to reduce the likelihood of damage during an earthquake.
Please contact Bruker for more information on earthquake securing equipment.
2.7 Country-specific Safety Regulations
In addition to the above safety precautions, any country-specific safety regulations for
operating NMR systems must be fulfilled. These may include, for example, regulations
on:
• Facilities of a controlled access area around the magnet.
• Working conditions at computer stations.

10 B127527_00_03
Safety
This page intentionally left blank

11
B127527_00_03
3 Magnet Access and Rigging
3.1 Introduction
The magnet is very fragile, thus requires special consideration during delivery and
movement to its final installation point. It can be like other components of the
spectrometer system (console, BMPC, etc.) typically be removed from delivery trucks
with forklift and be positioned in the NMR lab with a pallet jack. Specifications for these
components are also included in this chapter for planning purposes.
3.2 Considerations for Off-loading on Site
When planning for off loading the magnet and console during delivery, the following
factors must be considered.
3.2.1 Delivery Area
There must be sufficient space in the driveway or parking area for the delivery truck and
in case a fork-lift has to be used to unload the crates.
3.2.2 Transport Weight
The Fourier system is shipped in 3 package units:
Table 3.1: Transport weight of the Fourier system
The shipment may contain other package units:
Table 3.2: Transport weight of additional components
Unit Weight
Magnet with crate 313 kg
Console, Cables, Filter, Manual 65 kg
PC, Monitor, Probe 65 kg
Unit Weight
SampleXpress Light if included in the order 40 kg
UPS if included in the order 40 kg
Tripod 35 kg

12 B127527_00_03
Magnet Access and Rigging
3.2.3 Equipment Requirements
Small rigging devices can be used to off-load the magnet and other boxes.
•Fork-lift: It may be feasible to use a fork-lift to pick the magnet and other boxes
from the truck and lower it to a flat surface.
•Pallet-jack: If a loading dock is available, a pallet-jack can be used to upload the
magnet and other boxes from the truck.
3.3 Considerations for Transport to the NMR Room
Before delivery, one must ensure that the site provides adequate access for delivery of
the system and magnet. The following factors must be considered.
3.3.1 Accessibility to the NMR Room
•Theaccess clearance (height and width) and floor loading capacity must be
checked along the entire route that the magnet and console will take from the
loading dock to the NMR room (see 3.2.2 Transport Weight).
•Elevator capacity and dimensions must be considered if applicable.
• The transport will also be affected by floor level and presence of steps.
•Theturning radius can also be a factor if for example corners must be navigated.
3.3.2 Equipment Requirements
Depending on the situation it may be necessary to utilize a pallet-jack or a fork-lift to
transport the magnet and other boxes over floors and through passageways. The
magnet and other boxes must be moved in upright position.
3.4 Considerations for Assembling the Magnet
3.4.1 General Requirements
All the requirements discussed in this manual considering room layout must be met
before taking delivery of the system. The type of equipment used for assembly will
ultimately depend on any limiting factors, such as ceiling height.

13
B127527_00_03
Magnet Access and Rigging
3.4.2 Equipment Requirements
•Lifting Hook: Lifting the magnet inside the NMR room for assembly purposes
requires either a fixed lifting hook or a tripod gantry capable of handling the magnet
load with the given ceiling height requirements.
•Fixed Lifting Gantry (A-frame): If a hook can not be provided, the fixed lifting
gantry may be used instead.
Bruker can provide rigging equipment, such as Chain Hoist, Tripod or Gantry A-frame at
many sites upon request.
3.5 Checklist for Magnet Access and Rigging
Table 3.3: Magnet Access and Rigging checklist
Determine if there is sufficient space in the drive way or parking for the
forklift and for the delivery truck.
Determine if sufficiently leveled area is available for uncrating the mag-
net.
Determine if the elevation of the magnet room is different from the deliv-
ery area and make provision for overcoming this obstacle if necessary.
Determine if suitable leveled slab (area) is available in front of the access
doors for the transport device. Is the slab capable of handling the size
and weight of the magnet.
Determine if masonite sheets are needed to correct imperfection and pro-
tect flooring.
Determine if adequate clearance is available along the access path from
the delivery area to the NMR room.
Verify the load bearing capacity along the access path.
Verify fork-lift or pallete-jack accessibility.
Determine if there is adequate height clearance for rigging to lift the mag-
net in the NMR room. If a hook is used determine if hook height and lifting
load is adequate.

14 B127527_00_03
Magnet Access and Rigging
This page intentionally left blank

15
B127527_00_03
4 Lab Requirements
4.1 Room Layout
The Fourier system can be placed in to a small room area but certain requirements have
to be met. There should be a clear path, free of obstacles, to bring in containers to
service the magnet with liquid Nitrogen and Helium. The console can be placed close to
the magnet but it is recommended that the work station should be placed a minimum
distance away from the magnet. As a room layout example, the Fourier system with the
optional SampleXpress Lite is shown in Figure 4.1 below.
Figure 4.1: Room layout example of an installed Fourier system
4.2 Ceiling Height
A minimum ceiling height of 2.74 m (9 feet) is required for the clearance needed
above the magnet for assembly, energizing and filling liquid Helium.

16 B127527_00_03
Lab Requirements
4.2.1 Checklist for Ceiling Height Requirements
Table 4.1: Minimum ceiling height checklist
4.3 Footprint
Figure 4.2: Floor Layout
4.4 Minimum Floor Capacity
The floor must be sufficiently strong to support the mass of the equipment, plus the
weight of any installation devices such as pallet-jack, tripod, hoist etc.
A minimum floor capacity of 431 kg/m2is required to support all the above devices.
Determine if ceiling height is adequate for lifting the magnet into place in
the NMR room.
Determine if height is adequate for energizing based on type of transfer
lines used.
Determine if height above He transport dewar (for refilling) is adequate.
MAGNET
DATASTATION
AIR
POWEROUTLET
DATAPORT
POWEROUTLET
10 feet
3m
10 feet
3m
MINIMUMFLOORREQUIREMENT
MINIMUMFLOORREQUIREMENT
CONSOLE

17
B127527_00_03
Lab Requirements
4.5 Floor Types
Generally a liquid nitrogen resistant floor material must be used, such as PVC or wood
that has been painted or varnished.
Many of the system components contain highly sensitive electronic devices that must be
protected from Electrostatic Discharge (ESD) by proper floor covering and grounding
practices.
4.6 Vibration Isolation
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.
Normally spectrometers at a field of 300 MHz magnets, such as the Fourier normally do
not require anti-vibration devices. In case this becomes necessary, Bruker Biospin offers
vibration isolation devices.
4.6.1 Sources of Vibrations
• Random vibrations may be caused by moving chairs, doors, tables etc. in or around
the magnet room. This type of vibration is usually controllable, but when planning
the site you will need to take into consideration activities in rooms adjacent to the
magnet room.
• Sources of more regular vibrations are generators, compressors, fans, machinery
etc. Compressors must not be located in the NMR room and, if close enough, you
should consider mounting such items on vibration damping material. Air vibration
can be caused by ventilation or fans, windows in the magnet room must be located
and constructed in such a way that no sudden pressure fluctuations are produced
by winds.
• Vibrations from external sources such as cars, trains, airplanes, building sites etc.
Here the critical factor is the distance from the source to the NMR site, as well as
the type of ground over which the vibrations are transmitted.
4.7 Electromagnetic Interference
Electromagnetic Interference (EMI) can be defined as any electromagnetic disturbance
that interrupts, obstructs, or otherwise degrades the effective performance of electrical
equipment. Possible sources of interference are power lines which may carry fluctuating
loads, heavy duty transformers, large electric motors, air conditioning systems, power
transformers, etc.
The fluctuating electromagnetic fields arising from such devices can interfere with the
magnet homogeneity. Of particular concern are sudden changes in load as may be
produced by elevators, trams, subways etc. Some laboratory equipment such as mass
spectrometers and centrifuges will also give rise to fluctuating fields. Other sources of
interference include radio and television stations, satellites and other RF transmitters

18 B127527_00_03
Lab Requirements
that may operate in the vicinity of NMR frequencies of interest.
If you suspect that you have a source of interference located near the proposed
magnet site then you should contact Bruker Biospin for a site survey.
Types of EMF Interference
• DC Interference
• 50/60 Hz Interference
• Radio Frequency (RF) Interference
4.7.1 DC Interference
DC interference generally comes from devices operated on DC, such as elevators,
trains, subways, trams, etc. The locations of both the device and its power supply & lines
relative to the proposed NMR site are essential to the amplitude and orientation of DC
fields and how they may interfere with the NMR system. DC feeder lines are just as
disturbing as a subway, and they do not run necessarily parallel to the track.
4.7.1.1 Measuring DC Fluctuating Fields
DC EMF measurements should be conducted using a fluxgate magnetometer. The
fluxgate sensor is capable of accurately measuring magnetic field changes below 1mG.
The sensor is connected to a magnetometer, and the voltage output from the meter is
then converted into digital form. The magnetic field is recorded and plotted on a
computer display in real time.
4.7.1.2 Reducing DC Interference
The amplitude of the “full external perturbation” (peak-to-peak) is measured with the
fluxgate magnetometer at the proposed magnet location but in the absence of the
magnet. There are two levels of compensation against these external DC field
perturbations:
• First, the magnet screens itself against external perturbations, hence only a fraction
of the full perturbation is left at the magnet center. We call this residual field
perturbation after magnet screening. It’s value is relevant to NMR experiments
without lock and experiments using gradients which require lock hold.
• Second, the advanced digital NMR lock further minimizes the interference after
magnet screening.
4.7.1.3 Guidelines: DC Interference
When determining the effect of fluctuating magnetic fields, two parameters are
important: the size of the fluctuation and the rate of change (gradient).

19
B127527_00_03
Lab Requirements
•Field changes of between 0-5 mG, regardless of the gradient, are generally
considered harmless for standard NMR work. Likewise with Ultra Shield magnets
(only), field changes up to 10 mG are considered harmless. The effect of such
changes would be observable in only the most critical of experiments such as NOE
difference experiments.
• For field changes larger than 5 mG the lock system will compensate the
fluctuation, as long as the gradient is less than 5 mG/sec.
• For field gradients greater than 5 mG per second, NMR performance may be
affected.
Table 4.2 lists the minimum distances between the source of interference and the
magnet center.
Table 4.2: Minimum Distance from Electromagnetic Interference Sources
4.7.2 16-2/3 Hz and 50/60 Hz Interference
Interference from 16-2/3 Hz generally comes from modern electric trains and/or
streetcars that run at 16-2/3 Hz. Likewise, interference from 50/60 Hz generally comes
from electrical wiring, transformers and fluorescent lights in the magnet system area.
The magnetic field further modulates these interferences, increasing the likelihood of
disturbances.
4.7.2.1 Measuring 16-2/3 Hz and 50/60 Hz Fluctuating Fields
16-2/3 and 50/60 Hz EMF measurements should be conducted in the proposed NMR
room with power lines active using a hand-held meter. Specific locations that must be
checked include:
• Magnet area.
• Console area.
• Along the wall inside the NMR room at 5 cm (~2“) from the wall, and 10 cm (4“) from
the wall.
• Approximately 5 cm (~2“) below existing lights in the room.
• Near the main outlets 100 to 240 VAC locations in the room.
Source of Interference Recommended Minimum
Distance from Ultra Shield Magnet
DC Trams, Subways* 100 m
Elevators, Fork-lifts** 8 m
*Trams and Subways are also a source of vibrational interference.
**Depends on the lift geometry and material, these specifications may vary.

20 B127527_00_03
Lab Requirements
4.7.2.2 Reducing 16-2/3 Hz and 50/60 Hz Interference
The general goal of reducing 16-2/3 and 50/60 Hz interference is to shield the source of
the interference from the magnet system. Soft iron has been found to be effective in
reflecting this interference, and thus providing an effective shield for the magnet. Bruker
provides planning for shielding using various metals and shielding techniques, please
contact your Bruker office for further information.
4.7.2.3 Guidelines: 16-2/3 Hz and 50/60 Hz Interference
The amplitude threshold for causing interference is approx. 200 nT (2 mG RMS) for
unshielded magnets and 500 nT for shielded magnets, based on laboratory tests. Thus,
acceptable limits must be well below this whenever possible.
The magnet must not be placed within a 6.1 m (20’) radius of a normally-sized
transformer. If there is a large transformer adjacent to the proposed magnet location,
measurements will be required to determine if the transformer will adversely affect NMR
spectra.
The magnet must also not be placed directly under fluorescent lights, which may cause
some 50/60 Hz EMF, and more importantly may switch off temporarily during a quench.
4.7.3 RF Interference
The NMR instrument is effectively a very sensitive radio frequency receiver. Possible
sources of interference are local radio or television broadcasts, low Earth orbit satellite
systems, and signals emitted by personal paging systems. Of particular concern will be
interference at frequencies at which NMR experiments are carried out. Although the
interference effects will depend greatly on the strength of the transmitter, as a rule of
thumb only broadcasting transmitters located within a radius of approximately 
5 kilometers (3 miles) are likely sources of interference.
RF interference may also occur between two or more spectrometers located in close
proximity and operating at the same nominal 1H resonance frequency.
4.7.3.1 Measuring RF Fluctuating Fields
Radio Frequency interference measurements should be conducted using a spectrum
analyzer. The analysis should be done for the resonance frequency of each of the nuclei
of interest (proportional to the 1H resonance frequency of the spectrometer). The
minimum frequency sweep is 400 kHz. Any peaks with RF fields above -80 dBm should
be recorded, as well as any broad frequency ranges with any level of RF signals.
Table 4.3 contains a list of the most common studied nuclei at the corresponding
frequencies for 300 MHz NMR systems.