Leaking Pressure Keg ?

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Just_Pete

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So I've come to the conclusion that the pressure relief valve on my corny key is leaking pressure. At high pressure, say 28-38 PSI, there's no hissing coming from the keg. When I lower the pressure down to 5-8 PSI for pouring beer, there is hissing. I've lost all 5lb of CO2 because of this :mad:. Now the thing is I've already opened up the lid on my fully carbonated brew to unscrew the pressure relief valve and and to re check the O ring for leaks. I couldn't find any cracks or iffy rubber O rings but tomorrow I'm heading down to my not so local home brew supply store to pick up a new pressure relief valve as well as new O rings. Hopefully my beer won't go flat through the night and if it doesn't, should I be fine with re-opening the top lid to replace all the parts on it?
 

shortyjacobs

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Yes, you can open the lid up, just purge the headspace again with CO2 when you close it back up.

More importantly, it's most likely NOT your pressure relief valve. The pressure relief valve has a spring pushing it DOWN onto the lid, so it will fail at higher pressures, NOT lower ones. There is no possible mechanism for a pressure relief valve to fail at low pressure, but NOT high pressure. To put it simply, the higher the pressure, the WORSE the pressure relief seal.

It is, more likely, your lid O-ring or your dip-tube o-rings, as these rely on pressure to seal. Again, to put it simply, the higher the pressure, the BETTER the lid/dip-tube o-ring seals.

So, it sounds like lid/dip-tube orings to me...
 
OP
J

Just_Pete

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Yes, you can open the lid up, just purge the headspace again with CO2 when you close it back up.

More importantly, it's most likely NOT your pressure relief valve. The pressure relief valve has a spring pushing it DOWN onto the lid, so it will fail at higher pressures, NOT lower ones. There is no possible mechanism for a pressure relief valve to fail at low pressure, but NOT high pressure. To put it simply, the higher the pressure, the WORSE the pressure relief seal.

It is, more likely, your lid O-ring or your dip-tube o-rings, as these rely on pressure to seal. Again, to put it simply, the higher the pressure, the BETTER the lid/dip-tube o-ring seals.

So, it sounds like lid/dip-tube orings to me...
Thanks for the reply and the info. I'm gunna head out to the brew store in about an hour or so and pick up some new O rings and replace the lid as well as the dip-tube rubber. Hopefully it will fix my low PSI problem. Would you recommend some kind of rubber sealer application to help with sealing and longevity?
 

shortyjacobs

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Thanks for the reply and the info. I'm gunna head out to the brew store in about an hour or so and pick up some new O rings and replace the lid as well as the dip-tube rubber. Hopefully it will fix my low PSI problem. Would you recommend some kind of rubber sealer application to help with sealing and longevity?
I personally never use keg lube, as it makes cleanup stickier....I just bought O-rings from mcmaster. 20 bucks shipped got me 100 dip tube rings, 100 post rings, and 10 lid rings....I don't worry about longevity cuz they are so damn cheap :tank:.
 
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