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Hi Bridget,</div>
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We also have a LN2 pipeline with a self-filling buffer tank in the OIST cryo-EM facility. The system has a liquid-gas separator in front of an internal buffer tank to vent gaseous N2 when the lines are warm. The gas is vented outside. It takes about 10min to
cool down the 30 meters of vacuum-insulated stainless steel line from the >5000L external tank (which is filled every 3-4 weeks). The warm-up corresponds to loss of about 50L of LN2 each time the buffer tank is filled from a warm state. The buffer tank is
150L and a lower and upper threshold can be set with an electronic regulator for automatic filling once it gets near empty or full. When the lines are cold, the buffer tank is filled in 15min from near empty. It can also be used as a filling station for pressurized dewars. </div>
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<div dir="ltr" style="">In principle, multiple cryo scopes could be connected directly from this buffer tank - this is what it has been designed for. <span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 12pt;">However, unfortunately
someone decided years ago that such unattended filling may be too dangerous despite a closed circuit and multiple oxygen sensors with central alarm. So our cryo-TEMs have never been connected and regular </span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 12pt;">dewars are
filled instead from the buffer tank at this dispensing point, then shuttled over 10m to the scopes. So although we don't depend on LN2 dewar delivery from an </span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 12pt;">external
supplier, we </span><span style="font-size: 12pt;">disadvantages: still need to swap dewars, loose 50L each day for filling multiple dewars (not just for cryo-EM), and have danger of exposure to N2 gas when people use it </span><span style="font-size: 12pt;">for
filling </span><span style="font-size: 12pt;">non-pressurized open </span><span style="font-size: 12pt;">dewars.</span></div>
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But if the system were directly connected to the scopes as designed, it would be very nice indeed. I can send specifics if you like. Its price is not justified, however. Should minimize distance to external LN2 tank, and distance from buffer tank to scopes. With
6 scopes, a 300L buffer tank would maximize refilling intervals. <span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;">
Vibration and noise of our system during buffer tank filling </span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;">are
low, but worse</span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;"> when filling dewars from it - it should be </span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;">installed </span><span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;">outside
the actual scope room. It is very reliable, no concerns. But must consider local regulations about unattended filling. </span>Bulk delivery of LN2 by tanker is significantly cheaper than trucking in scope-ready dewars. This may compensate for loss due to warming
up lines. Bottom line is you want a self-filling buffer tank in the facility, not connect the scopes directly to the same LN2 line. It also minimizes vibration transfer to other scopes when one is on a filling cycle.</div>
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Best regards,</div>
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Matthias</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> 3dem <3dem-bounces@ncmir.ucsd.edu> on behalf of Bridget Carragher <bcarr@nysbc.org><br>
<b>Sent:</b> Saturday, January 19, 2019 2:27:40 AM<br>
<b>To:</b> 3dem@ncmir.ucsd.edu<br>
<b>Subject:</b> [3dem] LN2 supply?</font>
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<div class="PlainText">Hello all,<br>
We are building a new microscope suite for 3 Krios to add to the 3 we already have. As everyone who does this will know, managing the LN2 for these instruments becomes quite a burden in terms of swapping tanks, and managing storage and exchange of these tanks.
So we are considering piping LN2 directly into the rooms. Can anyone with experience please comment on:<br>
- Costs of LN2 when considering that the pipes needs to be cooled down prior to fill and the pipe runs are fairly lengthy from the central storage tank to the rooms.<br>
- Safety concerns in terms of filling accidents in the room displacing oxygen; is this a major problem compared to the 240L tanks<br>
- Concerns that if anything goes wrong with the central storage unit all 6 instruments would go down<br>
- Anything else?<br>
If people want to send their comments directly to me I will collate and share with the list after a few days.<br>
Thanks,<br>
Bridget<br>
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Bridget Carragher<br>
Simons Electron Microscopy Center<br>
New York Structural Biology Center<br>
89 Convent Avenue, New York NY 10027 <br>
(212) 939-0660; bcarr@nysbc.org<br>
National Resource for Automated Molecular Microscopy<br>
<a href="http://nramm.nysbc.org">http://nramm.nysbc.org</a><br>
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