[3dem] issues with liquid nitrogen tanks

[Craig Yoshioka]

That is an interesting setup, maintaining the tank pressure by putting back-pressure on the vent line.  I also found the double tank manifold interesting… we were recently wondering if something similar was possible in the hopes of increasing the reliability of auto-filling by having two tanks connected at the same time- sometimes our tank pressures drop too low because of stuck safety relief valves.

On that second note, does anyone have any experience with the “Whisper” silenced relief valves?  The dB of the ones on the tanks going off drives me crazy.  I was hoping these might kill two birds with one stone: quiet things down and provide more reliable safety venting.



On Jan 28, 2020, at 1:18 PM, Xu, Chen <Chen.Xu at umassmed.edu<mailto:Chen.Xu at umassmed.edu>> wrote:

Dear Paul,

I am more concerned about that the Nitrogen gas can rapidly expand to many times its liquid volume, displacing oxygen and posing a significant asphyxiation hazard. Not much to the pressure itself.

LN2 tanks should stays in area with O2 sensor.

I need to dig more on the safety issue due to high pressure specifically. I think it is a commonly used supply tank type. I am also interested in hearing from community about this.

Best -Chen

________________________________________
From: Paul Mooney <mooney at gatan.com<mailto:mooney at gatan.com>>
Sent: Tuesday, January 28, 2020 4:04 PM
To: Xu, Chen; Parent, Kristin; 3dem
Subject: RE: issues with liquid nitrogen tanks

Dear Chen,

Are you sure that there is no off-label safety issue here?  230 psi times roughly 600 square inches is about 70 tons or ~35 Honda Odysseys hanging perpendicular to the cross-section.  Our airgas LN2 tank at Gatan is labeled "25PSI".  Rapping on the tank with my knuckles makes me worry about 230psi.

Best,
Paul

-----Original Message-----
From: 3dem <3dem-bounces at ncmir.ucsd.edu<mailto:3dem-bounces at ncmir.ucsd.edu>> On Behalf Of Xu, Chen
Sent: Tuesday, January 28, 2020 12:36 PM
To: Parent, Kristin <kparent at msu.edu<mailto:kparent at msu.edu>>; 3dem <3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>>
Subject: Re: [3dem] issues with liquid nitrogen tanks

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NOTICE: This is an EXTERNAL email.
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Hi Kristin,

it happened at our site. Even fairly new tanks can have this too.

We came up with a relatively simple solution - to use a 230PSI pressure tank to help the two LN2 supply tanks. There is no check valve at "vert" port of supply tank so we can help to maintain reliable ~20PSI using high pressure tank. We hook two supply tanks to the system (via a not long VP pipe). This way, both tanks have the same pressure. I attached a picture here.

-Chen

________________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu<mailto:3dem-bounces at ncmir.ucsd.edu>> on behalf of Parent, Kristin <kparent at msu.edu<mailto:kparent at msu.edu>>
Sent: Tuesday, January 28, 2020 2:45 PM
To: 3dem
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
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