[3dem] liquid nitrogen supply lines

[Claire Atkinson]

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>
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>
> 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)
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