Dispensing LN2

[rickss69]

Finally picked up a dewar. My question is can I use the valve attached to dispense into another container or will I be better off just pouring?

[NoL]

Oh you grabbed that one!
Nice :)
Your going to have to test it if its controllable enough for you, I would suggest most likely a "Belled" needle valve to allow you to figure out the flow rate.
Try removing the top and see if it has a "draw" tube to the bottom of the dewar.

[Buckeye]

You are also going to need a tube coming out one of those valves to despense the LN2 into a thermo. A Phase Seperator will make it much easyer to get LN2 out also, other wise it will be like a Fire Extinguisher and you will get mostly gas and spray and not a lot of liquid.

Take it into your gas supplyer and see if they have any hoses and phase seperators that will fit that.

I tried using mine without the seperator at first, it was very hard getting any real amounts of LN2 out.

[rickss69]

You mean like this one Nol? I assume they use the top fitting to fill and the bottom one could be used to extract from pressure? There is a tube that extends to the bottom of the dewar...

[rickss69]

You are also going to need a tube coming out one of those valves to despense the LN2 into a thermo. A Phase Seperator will make it much easyer to get LN2 out also, other wise it will be like a Fire Extinguisher and you will get mostly gas and spray and not a lot of liquid.

Take it into your gas supplyer and see if they have any hoses and phase seperators that will fit that.

I tried using mine without the seperator at first, it was very hard getting any real amounts of LN2 out.

Phase Seperator...that sounds expensive Buckeye lol. What would be a ballpark figure for something like that?

[Buckeye]

It's just the copper thing on the end is all, I know fancy scarry name for it :)

Those come on the end of hoses also.

But I would take it in to your gas supplyer and have it checked out and see what they can do. It may work fine like it is, you won't know until you try it ;)

Is the seal around the neck of that, like an O-Ring or something ?

Ok I see that those two spring things coming off from the sides are what hold down the top. Good you will not build up a lot of pressure inside it then, you should be ok then.

[rickss69]

Thanks Buckeye. Yeah, it also has some sort of pop off valve built into the bottom valve as well.

[2chesapeakes]

Thanks Buckeye. Yeah, it also has some sort of pop off valve built into the bottom valve as well.

That should be a pressure relief. That type of dewar may take a while for the pressure to build to a point where you can use the valve to dispense. I had rented one similar to that and after a number of hours there was still not enough pressure built up to use the valve to extract the LN2. The dewar I have now is classified as a pressurized dewar. It is designed to build and maintain 22PSI. I can usually start dispensing immidiatly after it is filled. As for dispensing I looked at the hoses they sell to dispense then went to a hardware store and purchased a flexible 1/2" gas line and it fit perfectly to the valve.

[rickss69]

I will let AirGas look at it. They can probably tell or test what relief pressure is for the container.

[3oh6]

that is my exact dewar. i haven't had any luck with my pressurized withdrawl device but i am assuming it had something to do with the device itself, and mine is a completely different beast than yours. i just pour, comes out faster anyway, bit more effort and coordination though.

i am definitely interested to see how you make out with your withdrawl device though so keep this thread updated with progress.

[Buckeye]

That should be a pressure relief. That type of dewar may take a while for the pressure to build to a point where you can use the valve to dispense. I had rented one similar to that and after a number of hours there was still not enough pressure built up to use the valve to extract the LN2. The dewar I have now is classified as a pressurized dewar. It is designed to build and maintain 22PSI. I can usually start dispensing immidiatly after it is filled. As for dispensing I looked at the hoses they sell to dispense then went to a hardware store and purchased a flexible 1/2" gas line and it fit perfectly to the valve.

Yeah Jeff I was talking with my friend at Airgas yesterday and he told me about the differance between the different types of Dewars, I did not know that yours was a high pressure one.

Mine is a low pressure and takes awhile to get LN2 out of it after I fill it up, ticks me off actually.