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Density of gases in relation to leaks in system

aSilvrHaze

New member
Situation: pressurized system to 60#(using compressor), no leaks. Stupidly assumed 60 is 3x my normal pressure of ~ 20# so I should be good to go. Started a run using 70\30 mix, got up to 20# and a leak starts on my lower 6" clamp connection. Can anyone explain this logic to me? Does the density of the different gases (butane-propane mix vs compressed air) change the leak points or characteristics? or whatever the proper way to put it is, if that makes sense. Does pressure testing with nitrogen vs compressed air make a difference?
 

SkyHighLer

Got me a stone bad Mana
ICMag Donor
Veteran
When the temperature drops from the inrush of butane/propane the seal material contracts and hardens, and therefore doesn't seal as well?
 
That's one possibility I have experienced, and for this reason I pressure test with the system cold and let it come up to ambient temp.
 

Gray Wolf

A Posse ad Esse. From Possibility to realization.
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ICMag Donor
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Situation: pressurized system to 60#(using compressor), no leaks. Stupidly assumed 60 is 3x my normal pressure of ~ 20# so I should be good to go. Started a run using 70\30 mix, got up to 20# and a leak starts on my lower 6" clamp connection. Can anyone explain this logic to me? Does the density of the different gases (butane-propane mix vs compressed air) change the leak points or characteristics? or whatever the proper way to put it is, if that makes sense. Does pressure testing with nitrogen vs compressed air make a difference?


Propane vapor has a specific gravity of 1.898 and butane 2.07.

As SH notes, the temperature drops when you inject the LPG and the seals become less resilient.
 
I pull vac on all the vessel jackets and load the vessels with dry ice until they come to to about -75 (with them venting to atmosphere) and then empty them and pressure test.
 

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