CONTROLING PRESSURE BETWEEN TANKS

[cryovette]

Anyone have any knowledge about transfering a pressurized cryogen gas between two tanks...one insulated and the other is not (both are equal in volume). Both tanks must maintain a pressure through the transfer, which tanks are side by side and an insulated line connecting the two is less than a couple inches. The non-insulated tank must be drained completely and has a plate inside (controlled by a simple pneumatic tank that is less in pressure than cryogen pressure but can be increased if need be)that is intended to push against the cryogen once the valve has been opened between the two cryogen tanks...simply to empty the non-insulated tank of the cryogen gas. The two tanks are kept in a fairly cool room temp setting...I believe it averages around 50 degrees F.

It is absolutely important that the pressure does not increase in the transfer as the insulated tank must be immediately removed after transfer and connected to another station where a higher pressure would be catastrophic. A pressure drop would be ideal without having to incorporate any type of bleed off and lose any valuable gas (with the exception of a safety bleed off in case something malfunctions).

One idea we have had is to perhaps submerge the non-insulated tank in a liquid cryogen to help in cooling and reducing pressure in the initial tank? However, the problem is that this could only be a very brief time period...seconds at best. Another idea is to increase the size of the insulated tank to a volume that would give us a 500 psi pressure drop...but wouldn't the gas expand and therefore slightly drop in temperature and see even more of a pressure loss (even though both are pressurized...one just 500 psi more than the other)?

 

[dcasto]

draw it out and post, that may help.

 

[danthemeterman]

post ?

 

[someguy79]

As dcasto said, a drawing of the configuration would help. From your description it's hard to tell exactly how many tanks you are dealing with and how each is to function.

If I read your post correctly:
1 you have to empty an uninsulated tank of some cryogen into a second insulated tank.
2 Increased pressure in the insulated tank is not acceptable.
3 The uninsulated tank contains a gas when full.
4 Leakage of the gas to atmosphere is not acceptable.

Here are a few questions, that if answered, may result in more meaningful discussion.
1 What sort of fluids are of interest?
2 What are the temperature and pressure limitations of the tanks?
3 How much material must be dealt with and how fast?
4 Is this activity to happen regularly, continually, or only as a one time event?
5 Must the uninsulated tank be completely empty of the fluid? (high vacuum), at a lower pressure? (1 atm for example), or must it be purged with some inert or something?