advice on dispensing from a pressurized dewar

[Joe Camel]

i have a dewar that i obtained on ebay a while back and im getting very close to being ready to use it.

im looking for advice on how to "pipe" a dispensing mechanism.

here are a few shots of the dewar:























obviously, the safety valve will release @ 22 psi and the "VENT" will allow me to release pressure below that.

(again) obviously, the "LIQUID" valve will release liquid but this is where im looking for experience and suggestions.

can i just run "hardware store" pipe from the end of the valve?

should i keep the same diameter of pipe the whole way through to the end or should i step it up to try to reduce the speed of the liquid as it reaches the end of the pipe?


please feel free to make any suggestions (other than give YOU the dewar)




thanks for the (extreme) advice




.

[CryptiK]

What we use at work is a segmented metal pipe with a metal nozzle on the end to dispense the LN2. It is made of many small (~1cm) interlocking metal segments that are flexible and allow the pipe to bend (metal segments look sort of like this: ]]]]]]]]]]]]]]]]]] ) .

When you say 'hardware store pipe" do you mean plastic? If so, I would try and avoid it, as it will become very brittle while dispensing the LN2. However if you have no other options, you could somehow anchor some pipe so that is was not able to flex and run it down the side of the dewar so you place the smaller dewar/flask on the ground under the pipe opening and just open the valve carefully and fill it up without flexing it.

However someone who doesn't use the appropriate pipe may have a better idea.

[Buckeye]

That looks a lot like Philly_Boys. PM him and see if he can give you some pointers.

[Planet]

If I dont have a tube with me to go on it. I just put the flask up to the liquid line. If you have a flaring tool, proper flare nut, some copper tubing, and insulation you can make your own.

[Buckeye]

Or I found the guys at AirGas to be very helpful. You could take it to them and see what they can come up with. Shouldn't cost very much even if they put a flex line on it with a diffuser on the end.

[Joe Camel]

plastic was NEVER a consideration!




i like the Airgas suggestion... i just hated the thought of going there for a fill-up and not having a plan
im sure after my first tank ill become more comfortable using LN2 but for a first timer its still "scary stuff"





i knew there must be a cheaper way than this Cobraflex (vacuum sealed) stuff, @ $950+ for 4' .... ummmm ya ...









fell free to add more suggestions/comments



.

[Nosfer@tu]

I saw a hose on Ebay the other day....

165 $ or so...

Same size and make sure it is build for ln2.

You can add a cobber star or what ever they are called.
it will reduce splashing of the ln2.

I will try and look for it so you can get a hold of one of them

[Nosfer@tu]

here is a few, still looking for the brass/copper thing for the end.
http://cgi.ebay.com/CTI-Stainless-St...QQcmdZViewItem
http://cgi.ebay.com/CTI-Stainless-St...QQcmdZViewItem
http://cgi.ebay.com/SWAGELOK-FLEXIBL...QQcmdZViewItem
http://cgi.ebay.com/SWAGELOK-FLEXIBL...QQcmdZViewItem

[Joe Camel]

yes please, "splashing" LN2 does NOT sound like fun




i assume if im going to rig something i want it to be low mass. chilling a 1/4" thick 3' section of cast-iron pipe sounds like it would burn off A LOT of LN2 B4 i get any liquid out the other end.

decisions decisions... do i get a tank full tomorrow or wait an entire week (Wednesday = only day i can take off work to get a fill)

hummm think i need to make a stop @ the hardware store and see what i have to play with


THANKS for the comments!!
(keep'm coming)

[Nosfer@tu]

You cant get it filled unless they have hoses to connect, or you can unscrew the top.

DONT USE Things that are not certified for ln2.
Ln2 expands 700-800 times = DANGERUS.

And using non certified hoses = Danger.
If you can fill her up and let her stand, she can hold it for WEEKS if not a few months

The links I was talking about

https://www.labrepco.com/store.php?f...357&cat3id=105

http://www.discountcryo.com/ProductD...Code=1700-9C65

[[XC] gomeler]

I just fill from the liquid feed ports with a large thermos

[Joe Camel]

the safety ring is sorta in the way but i guess i can see how thats possible


ill get the tank filled (does have a screw off top) and see what the Airgas place has/suggests


i never would have thought it could hold for week(S) thats GREAT info!


im assuming ill dispense into "the Rock" first then into the smaller one for a more accurate mOUSE pOT (Rev4) pour.

[CryptiK]

Yes we use the CobraFlex at work, I didn't realize it was so expensive. Perhaps the home made copper line would be the best and least expensive solution.

[toddm27]

here's the pdf to my withdrawal device, all it is is a tube connected to the fittings, no insulation, all the same diameter, works fine,
http://www.taylor-wharton.com/pages/.../RDF/tw-43.pdf
and that piece on the end of the tube is missing on mine, doesn't affect it at all though

[Joe Camel]

4' section of flex-line and phase separator (35L of LN2 too) in "hand"

Airgas wouldnt/couldnt but Praxair did


thank you ALL !!!



(pix when i get out of work)

[Joe Camel]

woot XS is BAAaak









and a shot of my virgin LN2 run (last night)






after spending the 200 on the hose and phase separator, ive decided it takes too much LN2 to cool it all down B4 any liquid comes out and will be making my own. o-well live and learn



.

[Joe Camel]

works much MUCH better

cools down and gets liquid out in 1/4 the time it took to cool down the 4' transfer hose

[Oliver]

Awesome setup you have grabbed Joe_Camel, i like your bench place

Looking forward to see some numbers being pushed

[Joe Camel]

thanks

that's inside the break room @ the family business, after everyone has long gone home

AC set to 65F

the condo i live in is too small (wife, me, 4 cats, 15 month old daughter) to do LN2 in, D-ice/SS etc is fine but not LN2


I look forward to pushing some BIG #'s


this is all ive got to show so far




i think the F1-EE should help