If its blowing off thats a good thing. Now I would not worry too much since it will take a little more that 15PSI pop the hood on a dewar. I'm sure something is froze on this thing and will be good as you start emptying it. I think this may be a product of too fast filling by the dude.

warm car too so thats not helping the pressure any

Mine only did that when the Airgas manager filled mine. He filled it through the discharge unit whereas Jose who normally fills it removes the discarge unit and fills it with the dewar open.

The time the manager did it, he left the vent valve open and I closed it about half way home. Don't remember getting all that much product out of it that time either though :(

Whe the guy removes the discharge unit he fills it all the way to the top, and since there is so little room left for air, it generates very little pressure until I start using it. The less it contains, the more pressure it seems to build ?

Hope you got enough when you went to bench Spliggitybro

makes perfect sense maadd thanks for the insight! just so happens the old guy that usually fills it said he usually takes the discharge unit off and this guy obviously did not.

On the side of the Dewar there should be a safety blow off valve, looks like a round plug thing sticking out the side. Is this where its coming from ?

If it is it will not hold any LN2 for very long at all

nope this is right where the psi gauge is and it quit once I lugged it upstairs and it cooled off a bit in my apartment. Was hot to the touch sitting in my 90 degree car lol

I always take my transfer device off when filling my 25L. Never had it pop off before.

I should start having them fill it without the top as well, I get the feeling I would get a lot more ln2 per fill if I did.

Thats how they fill mine. I take off the top and they just drop a hose into it and away it goes.

Like was said before, mine is a low pressure Dewar so when its full I generally have to let it sit over night before I can start getting a good flow of liquid out of it. I have seen a way to pressure the tank tho., but it requires a few fitting and a tank of LN gas to do it.

My 50L has never vented, but the 160L's low pressure Dewars I have had vented a lot. 230L high pressure one vented very little.

You could always go back and stuff the technician into the blow off valve and see if that stops it.