NMR device is operated by a dedicated specialist and the device and its components are not to be handled or removed without any permission under any circumstance. The following text is only intended to inform you about the device
A superconducting magnet is an electromagnet that is built using superconducting coils.
Our 500 MHz magnet system comprises of a fully persistent 11.74 Tesla magnet which is immersed in a bath of liquid helium (-269 °C) at which temperature the resistance of the coil is zero; once energized the magnet can run continuously.
The helium vessel is shielded from room temperature by a vessel filled with liquid nitrogen (-196 °C) and an outer vacuum to keep the liquid helium from rapidly boiling off.
The liquid helium and liquid nitrogen are not pressurized but are allowed to boil-off over a number of weeks; liquid helium and nitrogen must be added periodically.
The magnet is always on.
Magnetic Field Strength
Magnet strength is described in terms of Gauss or Tesla units (1 T = 10,000 G).
- Earth’s magnetic field: 0.6 Gauss at the equator
- Small bar magnet: 100 Gauss
- Refrigerator magnet: 100 - 150 Gauss
- MRI medical scanners: 0.3 - 1.5 Tesla (3 - 15,000 G)
High magnetic field NMR spectrometers and other superconducting magnets:
- 200 MHz: 4.7 Tesla (47,000 G)
- 300 MHz: 7.0 Tesla (70,000 G)
- 500 MHz: 11.7 Tesla (117,000 G)
- 800 MHz: 18.8 Tesla (181,000 G)
Surface of a neutron star: 1x108 Tesla (1012 Gauss)
Exposure to strong magnetic fields can cause serious injury or death and significant damage to personal property, equipment and data.
- 5-gauss perimeter should be minded by individuals with medical devices (e.g. cardiac pacemakers and metal prostheses). People using pacemakers, prosthetic parts and metal blood vessel clips should contact their physicians about the possible health risks before entering the NMR room because of the fact that the NMR spectrometers generate strong magnetic fields.
- Strong magnetic fields surrounding the NMR spectrometers can damage floppy disks, tapes, cards with magnetic strips, cellular phones, laptops and mechanical watches, so they should remain outside the 5-Gauss perimeter.
- Strong magnetic fields attract objects containing steel, iron, and other ferromagnetic materials (i.e., electronic equipment, compressed gas cylinders, steel chairs, and steel carts), so they should remain outside the 5-gauss perimeter. Personal injury and extensive damage to the probe, Dewar, and superconducting solenoid may be caused as these objects can fly toward the magnet. Only non-ferromagnetic materials are allowed to be used near the instruments.
- The magnet/Dewar has a high center of gravity and may collapse in an earthquake or if struck by a large object. People near the magnet may face serious injuries and the sudden release of nitrogen and helium gases from the Dewar will displace breathable oxygen in the room. The instruments are supported by anti-vibration legs that are attached to the floor.
- In the event of a "magnet quench" (sudden release of gases from the Dewar), leave the room immediately and contact NMR LS. Rapid expansion of liquid helium or nitrogen gas can displace breathable oxygen in the room creating the possibility of asphyxiation. Do not re-enter the room until the oxygen level has returned to normal. See specific “Cryogenic Purge – Quench” instructions.
- Handling cryogens is dangerous and can cause serious burns. Therefore, only individuals who have had special training and wear safety glasses, gloves and closed toed shoes should transfer liquid helium and nitrogen to the instruments.
- If you’re performing a temperature change experiment, always wear safety glasses near the magnet. Sample subjected to a temperature change can build up excessive pressure which can break the sample tube and broken glass and hot or toxic chemicals can cause injury. To avoid this hazard, establish the freezing and boiling points of a sample and never rapidly heat or cool a sample.
- Extra caution should be provided about the sample tubes as they are fragile and break easily. Removing the probe, the top of the sample tube can break off. The sample should be ejected before removing the probe from the magnet. Use extreme caution when removing the probe if the sample cannot be ejected.
- In the presence of flammable gases or fumes, NMR spectrometers should not be operated as there is risk of injury or death from inhalation, fire and explosion created by flammable gases or fumes.
- If a probe is in place, looking down the barrel of an NMR spectrometer should be avoided. Pneumatic ejection of a sample from the probe could cause injury.
References and sources for information from the relevant websites and documentation of different universities, NGOs and government agencies used in the preparation of this website are provided at references.