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fredsam25 t1_iso3ny0 wrote

MRI machines are currently being developed that could run on liquid hydrogen and even liquid nitrogen. The downside is of course cost, as these new machines cost a lot more. The thing that will drive the mass adoption of them will be a vast increase in the cost of helium or the complete collapse of the supply.

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WahooSS238 t1_iso6dby wrote

Liquid hydrogen seems like it would be a massive safety hazard, no?

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fredsam25 t1_isoekpj wrote

Hazards can be managed. It's just about cost.

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bundt_chi t1_isol6c2 wrote

Most medical facilities already have lines to supply oxygen throughout a building which is itself a dangerous gas. I would think they should be relatively well equipped to manage the risks of hydrogen.

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Kantas t1_isoz6wx wrote

Plus, if the liquid O2 and liquid H2 lines rupture and mix we will get the first lunar hospital as well!

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mrbellthebutler t1_isp3q13 wrote

Oxygen units gaseous form only becomes dangerous when it makes up 23% (it only makes up 21% of the air we breath) of the surrounding atmosphere. Oxygen arrives at hospitals in liquid form and goes through a process to turn it back into a gas which is easier to move through the hospital. Also, gases such as nitrous oxide, entinox (50/50 nitrous oxide and oxygen) and heliox are generally present in them. Hydrogen lines have a whole new set up to work on. For example releasing hydrogen gas you have to put it into a bucket of water and release it that way not straight into the atmosphere.

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bundt_chi t1_ispc97c wrote

I don't think MRI machines would require a liquid hydrogen supply line, i may be wrong. My point was that they likely already have and understand hazardous gas management procedures.

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mrbellthebutler t1_ispo090 wrote

No you are right. I was more thinking along the lines of hydrogen in general being used if it could be. You are also correct on the procedures etc. Part of my job is I am a Medical Gas AP so I am authorized to work on pharmaceutical, technical & medical gases so I know exactly what you mean in regard to management procedures.

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Fluffy-Jackfruit-930 t1_isq34hc wrote

No one is using hydrogen. Nitrogen is old and obsolete.

The current technology is "zero-cryogen" superconducting magnets. These use conventional niobium-titanium LTS magnets which are cooled by direct conduction to a heat exchanger in which is circulated a few grams of cold helium. This is a big change from the older generation of MRI technology which immersed the magnets in up to 150 kg of liquid helium, and used a "cold-head" to recondense helium which boiled off.

Zero cryogen magnets have several advantages, not just the fact that they don't need 100 kg+ of helium. The coolant circuit is sealed, so there is no leakage or boiloff. Similarly, there is no loss of coolant in the event of quench or emergency ramp down. A quench on an immersed magnet is a big problem, and recovery can take days. You can often recover a quench on a zero-cryogen magnet with a power cycle, which will initiate an automatic cool-down and ramp.

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