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March 23, 2020

NMR Magnet Maintenance Advice in the Wake of COVID-19 Restrictions

As more and more states institute “Stay in place/home” orders for non-essential businesses/institutions, we are aware that many institutions and facilities may be closed for an unknown period of time.
Please Note: Switching off Super Conducting Magnets is not possible!  Cryogen levels (liquid helium and liquid nitrogen) within the magnet need to be maintained to keep the magnet functioning.

JEOL always recommends a weekly nitrogen fill. It is also recommended that Helium refills be performed before the minimum Liquid Helium refill level is reached.

  • For most magnets, Liquid Nitrogen can go two weeks between fills.  Refer to the magnet book for specifics related to your magnet.
  • Minimum safe helium levels vary between magnets.  Refer to the magnet book for specifics related to your magnet. 
  • If regular liquid nitrogen refills are not possible, helium consumption will rise significantly.

Once the helium level drops below a critical level, either due to a lack of liquid nitrogen or a delayed helium fill, the magnet will cease to be super-conducting and release its energy, i.e., "quench".  Liquid Helium that remains will rapidly release as Helium gas.

  • Magnets are designed to cope with an unexpected quench but there is always the risk of mechanical damage should this happen.
  • In most cases, the magnet can be re-energized. This would however be at considerable cost and with lengthy downtime in the interim.
Therefore, we strongly recommend that every effort be made and priority given to maintain the cryogen levels of the magnet.

If at some stage it becomes evident that this is not possible and a controlled de-energization is required, we would recommend that the magnet be de-energized in a controlled manner to prevent a quench. We would need to advise on the minimum helium level to do this safely. This again depends on the magnet type and field strength.  Please contact JEOL USA service as soon as possible, if this is the case, and also download and submit this PDF form for expedited service.

 
Best regards,
JEOL USA, Inc.