Why would a mint need liquid nitrogen?

[pharman]

Why is there a big tank of liquid nitrogen outside of San Francisco’s mint? How is it used in the minting process?

[ChrisBooth12]

If i had to guess I would say they use it to cool some piece of equipment

[Inigo_Montoya]

@ChrisBooth12

If i had to guess I would say they use it to cool some piece of equipment

You mean, like when they make cold, hard cash?

[Bosda_Di_Chi_of_Tricor]

Oh.

That kind of mint.

I just thought somebody was marketing a new candy, one that takes things too far.

[johnpost]

besides cooling it could be used to provide an oxygen free environment.

[yoyodyne]

It’s used to quench (rapidly cool) a coin die with high-pressure N[sub]2[/sub] gas after heat-treatment in a vacuum oven, in order to harden it and extend its working life. Nitrogen can also be used mixed with hydrogen (called a forming gas) to heat (soft anneal) the metal strips used to make coin blanks in order to make them easier to strike.

[Chronos]

That, and so the employees’ cafeteria can make ice cream.

Mmm, liquid nitrogen ice cream…

[schnuckiputzi]

I was thinking coooollll, minty freshness…No?

[billfish678]

@ChrisBooth12

If i had to guess I would say they use it to cool some piece of equipment

We used to have to keep it around for an electron scanning microscope. That scope HAD to STAY cold too. If it ever got warmed up, apparently bad expensive things happened.

Whether a mint uses such a fancy scope I have no idea. But I could at least imagine it could.

[JWT_Kottekoe]

@billfish678

That scope HAD to STAY cold too. If it ever got warmed up, apparently bad expensive things happened.

That would be to prevent the energy dispersive Xray (EDAX) detector from warming up. If a lithium drift detector gets warm (not to be confused with a dilithium crystal, Scotty), the lithium diffuses and the device is destroyed.

[gotpasswords]

@yoyodyne

It’s used to quench (rapidly cool) a coin die with high-pressure N[sub]2[/sub] gas after heat-treatment in a vacuum oven, in order to harden it and extend its working life. Nitrogen can also be used mixed with hydrogen (called a forming gas) to heat (soft anneal) the metal strips used to make coin blanks in order to make them easier to strike.

Found a cite for that…

@Messer (A European industrial gas supplier)

The coining dies are heated in a vacuum oven, from which the oxygen in the atmosphere has been extracted, and they are heated there to the correct hardening temperature. Finally, the treatment chamber is flooded with pure nitrogen and the master die is cooled very rapidly under great nitrogen pressure, in other words, ‘quenched’. The inert nitrogen not only hardens the steel; it also prevents any unwanted discolouration on the surface.

(From http://www.messergroup.com/de/interviews/kunden/onair7/index.html?iLangID=1)

[WarmNPrickly]

@Bosda_Di_Chi_of_Tricor

Oh.

That kind of mint.

I just thought somebody was marketing a new candy, one that takes things too far.

When I bite into a York Peppermint Patty …

Call 911 he just bit into a York Peppermint Patty!