SAFETY FOR NUCLEAR MAGNETIC RESONANCE (NMR) FACILITY

SAFETY IN THE NUCLEAR MAGNETIC RESONANCE (NMR) FACILITY

NMR instruments use a static magnetic field to make nuclear spins orient in the magnetic field. There are different strengths of magnets from 1,500 to 200,000 gauss (0.15 to 21 tesla). Field strengths correlate with the proton frequency of the instruments here at the UNSW NMR Facility:

1H Frequency (MHz)Field (Tesla, T)Horizontal distance of 5gauss line (in metres) from centre of the magnet *

Bruker 30071.8

Bruker 50011.43.5

Bruker 600143.6

*vertical distances are larger

These are the strengths of fields at the centre of the magnet. Fields at the extremities of the magnet casing do not exceed 2 tesla. No permanent biological effects have been measured in humans below this field strength. The magnetic field drops rapidly with increasing distance from the centre of the magnet and an important measurement is the distance from the centre of the magnet at which the field drops to 5 gauss, which is the cut off point for most safety issues. The main safety concerns are:

1)The large magnetic field which attract ferromagnetic objects, and

2)The cryogens which may cause burns when as liquids they contact with the skin or by asphyxiation when present in large concentrations produced by a quench or container failure.

RISK ASSESSMENT FOR GENERAL USAGE

Strong Magnetic Fields

The magnet of a spectrometer is ALWAYS at field. Strong fields are produced outside the magnet; therefore, no movable metal objects should be taken within the ~2 to 5metres (3 to 5 gauss) radius of the instrument. Small, sharp metal objects flying towards the magnet are highly dangerous. Larger objects are troublesome to scrape off the magnet, and can seriously damage the magnet. Very large objects have been known to break the cryogen dewar(s) in the magnets resulting in the release of the cryogens contained in the magnet (See Quench). Magnetic objects flying towards the magnet pose threat of serious injury/death to any person in the way.

Metal belt buckles, steel tipped shoes, paper clips, hair pins, and any other metal on the person may be strongly attracted when close to the magnet.

Persons fitted with pacemakers should not enter rooms containing spectrometers. Magnetic fields may affect heart pacemakers. Demand-type pacemakers may be switched to basic rate pacing.

Persons fitted with metallic implants and prostheses should not get closer than the 5 gauss line of a magnet.

Magnetic fields may permanently damage analogue watches, calculators and certain types of credit cards and mobile phones. Keep those items more than 2.5m away from the center of magnet.

NMR workers should spend no longer than reasonable necessary within the 5gauss line for sample changing and adjustments.

Hands and arms etc. should not be placed into the bore of the magnet (widebore VI 300).

Cryogenic Liquids

In the unlikely event of the magnet quenching (the rapid release of gaseous cryogens from the cryostat into the room) or of a cryogenic container failure, up to 100m3 of helium gas may evolve over a period of several minutes. Although inert, lighter than air and non-toxic, there could be a risk of asphyxiation in a confined space. Personnel should evacuate the NMR laboratory IMMEDIATELY in such a situation. A quench warranting evacuation would be obvious by the noise of the escaping gas and clouds of vapor. Similarly, rupture of a liquid nitrogen container resulting in a large volume of nitrogen gas being released also requires evacuation of the laboratory.

Failure to refill or de-energize the magnet when low levels are indicated by cryogen level sensors may result in a magnet quench with possible magnet damage. If low level warning lights on sensors are continuously lit and warning messages are displayed on the BSMS instrument panel, immediately inform the NMR facility staff.

Electrical Hazards

Electrical/RF hazards: Risks are similar to those encountered in the use/maintenance of other laboratory equipment. Changes to cables and wiring should only be made by NMR Facility staff.

In case of serious flooding, or in other situations where there is risk of electrocution, the equipment circuit breakers will be turned off by NMR Facility staff.

Sample Care

Breakage and Accidents

ALL accidents inside the probe (e.g. broken tubes) MUST be reported to NMR Facility staff immediately. Knowledge of any chemicals involved is crucial for clean up. All spills/breakages outside the magnets should also be cleaned up using the appropriate methods outlined on the relevant MSDS.

Solvent Exposure

Samples in organic solvents should not be prepared in the spectrometer rooms. Use your own laboratories or the prep lab (B61).

Labelling and Disposal of Samples

All NMR samples must be labelled with owners name and an appropriate identifier to avoid safety issues of unknown compounds.

All users must dispose of their own samples in their own laboratories. Short term storage of labeled NMR tubes in the spectrometer rooms (e.g. in the fridge) is permitted for samples that do not present significant safety risk.

Fire

Use only carbon dioxide fire extinguishers to avoid equipment damage.

RISK ASSESSMENT FOR CRYOGEN FILLS

When transferring liquid nitrogen or helium, the following steps should be observed to avoid accidents:

Only personnel trained by Facility staff following official procedures may perform cryogen fills.

Gloves, eye protection, and closed shoes (NOT STEEL CAPPED) must be worn.

All doors should be propped open to increase ventilation.

Only stainless steel transfer lines are to be used to avoid problems of cracking or magnetic attraction.

Tanks on wheels must be chocked or held by another person or transported on purpose built stable trolleys.

The transfer must be continuously attended.

No access to the pit (DMX 600) is permitted during nitrogen fills as exit is hampered and the cold N2 is denser than air.

Since the possibility of a quench is higher when filling the magnet, and since the transfer involves manual operations, there is a remote possibility that an operator could be rendered unconscious around the time of a quench. Fills should only be done by a single operator when the fill cannot be deferred, and exceptional caution should then be used.QUENCH

Currently, all superconducting magnets use liquid helium to maintain the magnet coils at a temperature enabling superconductivity. The helium and magnet coils are maintained in a vacuum. The temperature of liquid helium is approximately -269degreesC or 4.17degreesK. Liquid helium will boil at 4.22 degrees K. Any disruption to the temperature or loss of the vacuum will cause the liquid helium within the magnet to "boil off" causing an immediate and sudden loss of the magnetic field. This event is referred to as a "quench". When this occurs, the helium will expand at a rate of approximately 760 to 1. This means that for every litre of liquid helium, 760 litres of gas would be produced. This marked expansion in volume causes the gas to rush out of the magnet into the spectrometer room. Magnets in use hold more 100 litres of liquid helium and liquid nitrogen (DMX 600).

NMR Induction Safety Quiz

1) What does the 5gauss line mean?

2) Give three examples of magnetic objects?

3) What is a cryogen? Name the two liquid cryogens used in the magnets and their potential hazards?

4) What does asphyxiation mean?

5) What is a quench?

6) What should one do in an event of a quench?

7) Where is the NMR Prep Lab located?

8) How should an NMR tube be labelled?

9) How much deuterated solvent should be used in a 5mm NMR tube (if submitting a sample on an auto-sampler eg: GYRO)? (answer in cm)

10)How long should an NMR tube be? (if submitting a sample on an auto-sampler eg: GYRO)? (answer in cm)

11) What is the bore of the magnet?

12) Lab coats, food, drinks and plastic/latex gloves should not enter the NMR Lab (B41).

CONTROL Forms.OptionButton.1 \s 13) Indicate the location of a) i) on the map below:

a. 2 x Fire blankets, b.2 x Fire extinguishers and

c. 2 x Emergency Exits d.1 x First aid box

e. 1 x Safety shower f.1 x Eyewash

g. 3 x UNSW Emergency Procedure clip chart (2 x B41 and 1 x B42).

h. 1 x Broken glass bin i.telephone (in B41)

The NMR Declaration for Current and New NMR Users

While working in the NMR Facility, all users are required to comply with the occupational health and safety (OHS) procedures as specified in the OHS pages of the Analytical Centre and NMR Facilitys web site. Users are required to advise NMR staff as soon as possible or at least 24 hours prior to a booking that they wish to cancel. Failure to do this will result in the booked time being charged to the Users supervisors account. Users can only book time on NMR instruments with the approval of their supervisor(s) and access fees will be charged for all booked instrument time. Users must not interfere with any of the NMR instruments if they have not booked the time or are not licensed to use the instrument by NMR staff. Users must also agree not to provide access to the NMR Facility to unregistered users without the specific permission of the NMR staff. Users are not allowed to train other users, whether they are registered or not, unless permitted to do so by NMR staff. Users are not permitted to undertake any work that is not directly related to their project. Users agree to accurately complete all record keeping required by the NMR to monitor the use of instruments e.g. log books and booking systems. Users agree to report all faults or irregularities in the NMR instruments to a NMR staff member immediately they are known. Samples are the responsibility of the DIY user and the NMR Facility does not accept any responsibility for loss or damage of samples left in the facility. Data is the responsibility of the DIY user and the NMR Facility does not accept responsibility for loss or damage of data that has not been removed/copied/archived. Any work that is published or publicly presented, where all or a part of the work was undertaken in the NMR Facility, should acknowledge the role of the UNSW NMR Facility in providing access or contributing to or assisting in the work.

Failure to comply will result in the loss of access to the NMR Facility.

I _______________________________, have undertaken laboratory induction. I agree to abide by all the above requirements as outlined by the Laboratory Manager.

Signature_______________________________Date

_______________________________Gyro

Maya

ESR

Tesla

Manager

Scientific Officer

Store Room

Hertz

Flip

Gauss

NMR Processing Lab

Tech.

Officers

Entrance

Page 5 of 7Laboratory Induction and Authorisation Form Date Effective: 01/01/2007 Uncontrolled document when printed Current Version: 2.0, 01/03/2007

_1444796624.unknown

_1444796626.unknown

_1444796627.unknown

_1444796625.unknown

_1444796620.unknown

_1444796622.unknown

_1444796623.unknown

_1444796621.unknown

_1444796618.unknown

_1444796619.unknown

_1444796616.unknown

_1444796617.unknown

_1444796615.unknown