Quote:
Originally Posted by 2chesapeakes
The one I had borrowed was a storage dewar it is not designed to build pressure. It took 1.5 days for enough pressure to build to be able to usethe withdrawal device on the dewar.
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That sounds like how mine is, it never vents either but it only takes over night to build up pressure.
I had a 160L rental that was that way, took for ever to let pressure rebuild. But I was filling my 50L from it so I was really dumping pressure.
I am not sure why LN2 doesnt evap right away with open Dewars. I think it because its inside the Dewar which has been chilled down so it keeps the mass of LN2 cold for long periods of time.
I know most don't worry about it as most likely they get one filled and then use it all up over a weekend. I don't think it would last a long time tho., what bencher in there right mind would let a Dewar with LN2 sit and not use it for something, like Ice Drinks, Cooking With LN2, freezing bugs, cats tails etc
