[3dem] issues with liquid nitrogen tanks

[Parent, Kristin]

Hi Matthias,

Thanks for the comment. I am sending a picture of our setup since several others asked. It’s really convenient most of the time.

We seem to have problems only occasionally, and with one tank at a time. We noticed that if a tank’s pressure is read too low when hooked up to the system (even if the tank is brand new), the problem is independent of the side of the manifold and independent of the status of the other tank. For example, if the tank on the left side reads fine and the tank on the right too low (usually reads ~10 psi instead of 22 psi), unfortunately the problem follows the tank. If we swap them, the “good tank” on the left still reads fine when moved to the right and the 10psi tank still reads 10 psi even when now it’s on the left side.

It seems with our system, a partially filled tank does not provide enough pressure for the other side to work if the tank reads too low a pressure. But, we will try venting the tanks that are reading 10psi to see if over-filling is indeed the issue (that would be a very easy fix!).

Again, thank you everyone for the suggestions. Super helpful!

Kristin


From: Matthias Wolf <matthias.wolf at oist.jp>
Date: Wednesday, January 29, 2020 at 8:53 AM
To: "Parent, Kristin" <kparent at msu.edu>, 3dem <3dem at ncmir.ucsd.edu>
Subject: Re: [3dem] issues with liquid nitrogen tanks

Hi Kristin,

I doubt you have crappy tanks. Your supplier probably occasionally overfills them. When a tank is filled all the way to the top, there is no gaseous N2 to push out the liquid. In that case simply open the valve opposite of the LN2 valve for a limited time to generate pressure. Once there is sufficient volume of N2 on top, it becomes self-propelling.
It may help with your setup, if you  swap only one of the two bottles at a time, so that the half filled one provides enough pressure.

Matthias
________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Parent, Kristin <kparent at msu.edu>
Sent: Wednesday, January 29, 2020 07:21
To: 3dem
Subject: Re: [3dem] issues with liquid nitrogen tanks

Thank you everyone for the great suggestions!!! We have some things to try here and I hope it will get resolved easily.

Best,
Kristin

From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of "Parent, Kristin" <kparent at msu.edu>
Date: Tuesday, January 28, 2020 at 2:45 PM
To: 3dem <3dem at ncmir.ucsd.edu>
Subject: [3dem] issues with liquid nitrogen tanks

Hello fellow 3dem-ers,

We are experiencing quite an annoying situation with Airgas and I am wondering if other folks have had similar problems and what potential solutions are.

We have a custom manifold from Chart to deliver liquid nitrogen to our Talos Arctica that can be equipped with two 240L tanks, each with 22 psi pressure. This should help reduce the LN2 waste and be more efficient, and when our tanks are good, it really is amazing. BUT, some of the time Airgas gives us tanks that we cannot use as the pressure never builds beyond 10 psi and we have to return full tanks. They are not the nicest about this either ☹

We know the manifold is working correctly, and that it is caused by individual bad tanks. Has anyone else had crappy tanks? Do people just buy their own tanks and have them refilled instead of swapped?

Unfortunately, in Michigan Airgas is our only option, so any help would be appreciated.

Thanks in advance,
Kristin

--
Kristin N. Parent, PhD
JK Billman, Jr., MD Endowed Research Professor
Director, MSU Cryo-EM
Associate Professor of Biochemistry and Microbiology
Michigan State University
603 Wilson Rd
East Lansing, MI 48824
Phone: 517-432-8434
https://kparentlab.natsci.msu.edu/
Twitter: @Phage4Lyfe

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