After the latest announcement from the UK government regarding measures against the COVID-19 virus, we are aware that many institutions and facilities may be closed for an unknown period.
Unlike other equipment, NMR systems, specifically Super Conducting Magnets, cannot be simply switched off. 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 helium fill well before the minimum refill level is reached. We do however appreciate that this may be or could become difficult in the near future.
Regarding nitrogen, most magnets can in fact go two weeks between fills. Minimum safe helium levels vary between magnets. We can advise on this if required.
Should the nitrogen not be maintained, eventually the helium consumption would rise significantly. Once the helium level drops below a critical point, by either lack of nitrogen or a delayed helium fill, the magnet will cease to be super-conducting and dump its energy (a quench). Most of what cryogens remain can be quickly released as gas when this happens.
Although magnets are designed to cope with an unexpected quench, there is always the risk of mechanical damage should this happen. But in most cases, the magnet could be reinstalled. This would however be at considerable cost and with lengthy downtime in the interim.
We would therefore ask that every effort is made and priority is given to maintain the cryogen levels of the magnet.
If at some stage it becomes clear that this cannot be done, we would recommend that the magnet is de-energized in a controlled manner to prevent a quench. Please contact us ASAP in this case. We would need to advise on the minimum helium level to do this safely, which depends on the magnet type.
For any questions or concerns, we can be reached by calling our office on +44 (0)1707 377117, or by email at NMRsupport@jeoluk.com