[3dem] [External] Re: liquid nitrogen supply lines

[Morgan, David Gene]

Claire,

Thanks.  That is something I had not thought about.

--
    politics is more difficult than physics.
                                             A. Einstein

            David Gene Morgan
        Electron Microscopy Center
             047E Simon Hall
             IU Bloomington
          812 856 1457 (office)
          812 856 3221 (3200)
      https://urldefense.proofpoint.com/v2/url?u=http-3A__iubemcenter.indiana.edu&d=DwIFAw&c=-35OiAkTchMrZOngvJPOeA&r=L7-zyQ-04fFCMRqzLIOnx7H0exGZHwIQe_wMPuY600I&m=pDPxhkVVJGTIiQJNDUOURlX05kRbqZsqWgPQlCjgGBI&s=La3RhFmbUw9XOuLzfdao4FYHPV4YAm8uH1x0OoMt8S0&e= 

________________________________
From: Claire Atkinson <claire.elizabeth.atkinson at gmail.com>
Sent: Thursday, October 7, 2021 2:58 PM
To: Thomas Cleveland <thomas.cleveland at gmail.com>
Cc: Morgan, David Gene <dagmorga at indiana.edu>; 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: [External] Re: [3dem] liquid nitrogen supply lines

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Hi David,

Not a comment on copper lines per se but one thing to consider is the length/ volume of the new setup from the scope and how this will impact filling times, we had a longer than spec hose ship with our Glacios and were timing out on not filling the dewars by 20% in the specified time, causing it to time out and not fill at all. We had to replace the hose with a shorter one to avoid this issue. Probably worth checking with your TF engineer to make sure this doesn't happen to you...

HTH,

Claire

On Wed, 6 Oct 2021 at 12:03, Thomas Cleveland <thomas.cleveland at gmail.com<mailto:thomas.cleveland at gmail.com>> wrote:
Hi David,

I'm not an expert at cryo engineering so take this with a grain of salt, but I looked into this a while back for our facility and can share what I remember (we still haven't implemented anything, so I can't say from experience).

>From information I found online, it seems that copper piping is OK for liquid nitrogen, and has actually been used that way for a long time. There are a few special points, e.g. the joints need to be silver brazed, not soldered, to deal with temperature contraction. Traditionally, closed-cell urethane foam with a PVC outer jacket (as a vapor shield) was used to insulate cryogenic copper pipes. However, supposedly the repeated chill cycles cause this insulation to break down somewhat and lose performance over a few years. Whether this is a huge problem for you probably depends on how long your pipes are and how expensive your nitrogen supply is. A more modern and lower-maintenance (but more expensive) insulation method is to use vacuum-insulated lines, but I think this goes back to the stainless steel you were trying to avoid...

Best,
Tom




On Wed, Oct 6, 2021 at 1:56 PM Morgan, David Gene <dagmorga at indiana.edu<mailto:dagmorga at indiana.edu>> wrote:
Hi,

Does anyone have a good reason for not using copper pipes to supply liquid nitrogen to cryo-microscopes?

We are looking to move our liquid nitrogen tank further away from our Arctica.  We want to run an insulated line from the new location to where the tank stood and then use a flexible hose to connect from there to the instrument itself.  We can make this happen almost immediately if we use copper, but it will take months and months if we ask for stainless steel.

Thanks in advance for any advice.

--
    politics is more difficult than physics.
                                             A. Einstein

            David Gene Morgan
        Electron Microscopy Center
             047E Simon Hall
             IU Bloomington
          812 856 1457 (office)
          812 856 3221 (3200)
      https://urldefense.proofpoint.com/v2/url?u=http-3A__iubemcenter.indiana.edu&d=DwIFAw&c=-35OiAkTchMrZOngvJPOeA&r=L7-zyQ-04fFCMRqzLIOnx7H0exGZHwIQe_wMPuY600I&m=pDPxhkVVJGTIiQJNDUOURlX05kRbqZsqWgPQlCjgGBI&s=La3RhFmbUw9XOuLzfdao4FYHPV4YAm8uH1x0OoMt8S0&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__iubemcenter.indiana.edu&d=DwQFAw&c=-35OiAkTchMrZOngvJPOeA&r=L7-zyQ-04fFCMRqzLIOnx7H0exGZHwIQe_wMPuY600I&m=y3e-gKgl_EXGzBPi-24C-DHZCbVgFBjtlKdlrH6oIlg&s=ELo_Jn6Csff19K4OwPtoT20mAk6BgYmwTjxaSNoTdn4&e=>
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