Its Dewar Time!!!

Dawgdoc · Dec 26, 2007

Ok guys, I just got my 35L dewar in from Black Hole/Los Alamos Supply.

Not sure if I should be upset or not.

Dewar appears kinda old and cruddy, but I dont care what it looks like. They said they leak tested it and it passed ok.

Problem: There is no cap!! WTF?? Called them up and they said there is no cap for these dewars, and that I should get a piece of styrofoam, cut it out and wedge it in there. Is that legit???

Enclosed are pictures of the dewar as well as the skimmer valve/pressure gauge extraction device thingee. I have no clue how to use this thing or test it. Any advice would be appreciated.

Thanks!

Dawgdoc · Dec 26, 2007

last pic

Gautam · Dec 26, 2007

They just told me the same via email.

I've got no extraction device, but I do have another cap which I used.

In your case I think you should just use the extraction device as a cap.

Clockwork_Apple · Dec 26, 2007

Is this like a large vacuum flask for storing LN2?

i'm a bit lost :eh?:

Dawgdoc · Dec 26, 2007

Gautam said:
They just told me the same via email. I've got no extraction device, but I do have another cap which I used.

In your case I think you should just use the extraction device as a cap.

Any idea how to use the extraction device?

Any idea if I can purchase a cap elsewhere?

eaglescouter · Dec 26, 2007

From what I have seen of new dewars selling on ebay the cap is nothing more than a long plug of foam with groves on the edges (for allowing limited venting to prevent pressure build up) and glued/connected to a plastic loose fitting lid. But I've never seen one in real life.

El<(')>Maxi · Dec 26, 2007

Looks like a nice unit Russ. The withdrawal device appears to be a powered unit for measured dispensing, quite interesting. I don't know how it would work in our application but even if it doesn't, some of the parts on that unit can be used to make a 'traditional' withdrawal device. If you have no use for it or want it tested please contact me.

As far as a cap goes I bought one off eBay. It turned out I bought one for about $25 more than it should have been, when it arrived I looked up the company from the information on it and found I could have bought it here for less. The part number on mine is #10419/20N and fit's a 2.5" inlet.

Dawgdoc · Dec 26, 2007

Mark, as usual.....you are DA MAN.

TY for the info.

Im gonna fill this sucker up with water and try to figure out the extraction device. I would hate to spew LN2 all over the place LOL.

If it looks good, Ill use it. If i ant figure it out Ill styrofoam cap it and pour it into a container (what a PITA that is going to be).

BTW, this thing is HUGE!!! I wasnt expecting this big.

Got my mouser.com order today!! Im setting up for voltmods right now and will be dice benching again tonite after a little dinner

5Ghz Q6600 HERE I COME!!!!

Dawgdoc · Dec 26, 2007

Clockwork_Apple said:
Is this like a large vacuum flask for storing LN2?

i'm a bit lost

Clock, its a liquid nitrogen storage tank. It isnt vacuum sealed as far as I know, but the LN2 evaporates into gas and causes increased pressure in the tank, hence the need for some type of porous or gas releasing cap.

The extraction device Im clueless about. Like I said Im gonna water test it before any LN2 goes in there and see what happens

Joe Camel · Dec 26, 2007

the extraction device works like this:

the cap is an "air tight" fit... liquid LN2 turns into gas and builds up pressure in the tank... the long tube going down into the tank acts like a straw...after pressure is built up, you open the end of the "straw" and the pressure from inside the tank pushes liquid LN2 up and out of the tank through the "straw".

there is probably a safety pressure release valve set to a "safe" setting so not too much pressure is built up (IE BOOM!) and a manual valve that you can release all or most of the pressure inside the tank. (you could use this to reduce the amount of flow out of the straw by reducing the amount of pressure pushing it out)

now what that electrical switch on the valve is for is a really good question

assuming this container works like any ol' Thermos, there is a vacuum between the inner tank and the outer shell of the tank. vacuum = best insulator there is

PS GOOD LUCK!!!

toddm27 · Dec 27, 2007

nice, did you just end up getting one or 2 dewars?

Dawgdoc · Dec 27, 2007

toddm27 said:
nice, did you just end up getting one or 2 dewars?

2 dewars. 2nd one was shipped today.

I tried using this thing today without success. Mark, if you were serious and you dont mind, I would love to ship this thing to you to see if you can figure it out. I cannot.

Thanks again guys!!

Adragontattoo · Dec 27, 2007

water is not going to create the pressure needed to use the extraction device.

Basically think of a can of soda.

When it is fizzy and you hsake it it will foam everywhere and make a mess unless you vent the gas carefully

When it is flat, it does nothing at all when you shake it.

The LN2 evaporates to a gas form creating a pressure in the tank.

The extraction device has 2 releases, one is up high to prevent overloading the tank by releasing some pressure after X level (kind of like slowly releasing the fizz from a new soda) The second release (the one connected to the long tube, releases pressure by the gas PUSHING the liquid up the tube (lower pressure in the tube, like when you blow across a straw and it will suck up liquid from below) and out.

make more sense?

Dawgdoc · Dec 27, 2007

Makes sense yes, but I cannot find any valve/button/ANYTHING to allow me to take LN2 out of the container.

When the plug is inserted into a socket it start to hummmmmmmm, and there is 1 valve which appears to be a pressure release valve, but I have NO CLUE how to actually get the LN2 out of this dewar with this device

Adragontattoo · Dec 27, 2007

ok the green thing with the cable coming out appears to be a solenoid NO/NC I dont know.

The valve on the side is probably to release the LN2 but Im not sure, can you get some more pics of the assembly up for me to look at please?

EmAn · Dec 27, 2007

its also kind of like how a liquid barometer works if there is higher pressure then the liquid goes up higher and if there is lower pressure then the water level is lower but it will just end up with the water being pushed out since there is no way to stop the water so it just comes out

Dawgdoc · Dec 27, 2007

Adragontattoo said:
ok the green thing with the cable coming out appears to be a solenoid NO/NC I dont know.

The valve on the side is probably to release the LN2 but Im not sure, can you get some more pics of the assembly up for me to look at please?

As requested. As many more of any part as you want if these dont help enough.

Thanks for the input! I appreciate it

Dawgdoc · Dec 27, 2007

round 2

Dawgdoc · Dec 27, 2007

last one

El<(')>Maxi · Dec 27, 2007

The short silver valve is the pressure release, it works all on it's own. The other short one with the handle is a manual pressure release, used to fully release internal pressure so you can remove the withdrawal device when it's under pressure. Without that you'd have to take it off under 5-7 PSI, not safe!

Lastly, check the top of the ASACO solenoid valve, see that sliding clip on the very top over the round button? Try removing that and see if you can depress the round silver button when it's plugged in

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