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alrdop90172 t1_isnzntd wrote

They don't turn them off because it costs more to make them cold again than the electricity they would save

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Uncle_Budy t1_isp228u wrote

Anyone who does annual training at a facility with a magnet knows: THE MAGNET IS ALWAYS ON!

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PuffyPanda200 t1_ispazsy wrote

I did fire protection engineering and one of the business segments is healthcare (I still do fire protection engineering but in a different area now).

There are special non-ferrous (aka non-magnetic, they use Aluminum) pipe, sprinklers, fittings, etc. that are mainly used for MRI rooms. There are also nonferrous fire extinguishers located outside the rooms, these are typically a white and light blue coloring as opposed to the traditional red. There are also required to be big signs for firefighters to not enter the MRI room.

There are stories of firefighters going into MRI rooms (either they didn't notice the sign or it was not properly marked) and having their fire fighting ax ripped out of their hands by the magnet.

Then the problem is that the ax is basically stuck to the machine. Turning off the magnet is thousands of dollars so they will try to pull the ax off the the magnet with rope and a bunch of guys, sometimes that works, sometimes it does not.

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peoplerproblems t1_isqiyjt wrote

Yeah I want to see them try that on a 7T

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DariusMajewski t1_isqkzp3 wrote

Oh god the axe head would probably weld itself to something with the amount of force it would hit. Are 7Ts used in mainstream medical imaging yet? My dad is an MRI tech and just got a new 3T at his hospital.

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peoplerproblems t1_isqzha4 wrote

Yes! But only the big ones. Mayo Clinic is the only one I know of that got one in 2017

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PuffyPanda200 t1_isqmy85 wrote

I think that '7T' refers to 7 Teslas. I think (note that I am an engineer and not really involved in the response to the fires) that the main determining factor to if they can pull the ax off of the magnet is how close the ax got to the magnet. The force of the pull of the magnet is inverse (or inverse squared) to the distance so if the ax gets really close to the magnet then it is basically impossible.

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Illustrious_Crab1060 t1_ittuopi wrote

Why can't they cut the power to the magnet, without doing a quench? Or is it not an electromagnet?

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PuffyPanda200 t1_itv8gj3 wrote

It is an electron magnet. The medium that holds the electric flow to create the magnetic field is a superconductor, so no energy is needed to maintain the flow, so cutting power doesn't really help.

The aforementioned medium is kept cold by liquid Helium.

As stated I do fire protection, my explanation may be rudimentary in some ways.

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parallax1 t1_isp4nia wrote

Quenching them is when you really get screwed on cost.

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