Can't seem to diagnose CO2 leak

[Sixmilecross]

I picked up my co2 tank yesterday morning, braving the snow and wind at 7:30am in hopes that I could make up for the last co2 tank that just about emptied itself. When I got home, I connected the tank to the regulator, which has a washer at the seam, and a wye with two swivel nuts (each joint has teflon tape). I closed the swivel nuts, turned the knob shut on the regulator, and opened the co2 to check the tank seal first with a good spraying of starsan. No bubbles, cool. Moved onto the regulator opening the knob and sprayed the entire thing down, focusing on where it meets the wye - no bubbles. I screwed the air hoses onto the wye and opened the swivel nuts - no bubbles. Ecstatic

I hook up the gas to the keg and give everything a good spray down, and still no bubbles. I pull a pint of a Belgian dubbel I had sitting and really happy, although I noticed what seemed like air in the beer line, but figured it was just from reconnecting the line earlier. 3 pints later I still noticed it, and after opening the lid to diagnose, I noticed the psi on the tank had dropped from 800 to about 550/600. Devastated. I crank the psi up to about 30 and spray everything down - still no bubbles. Then I changed the beer line and went to sleep, leaving the psi up to see where the tank pressure was in the morning. Wake up and check it, and it seems unchanged.

My question is, what the heck is going on? I know changing the beer line didn't do anything to stop the leak, just coincidental. But I'm out of ideas at this point.

 

[IslandLizard]

Check the pressure relief valves including the one(s) on the regulator(s). I noticed mine are very, very sensitive. A light touch and it starts leaking ever so slightly, and you can't always hear it.

I've been after finding a small leak, since after I close the tank valve I tend to lose pressure in the (double) regulator manifold, slowly. The one gauge drops to 0 after a while. That pressure should stay.

Although Starsan is a good detector I prefer soapy water as it is less corrosive.

 

[Sixmilecross]

Thanks, I'll be sure to check that when I get home. I hope that's what the issue is as it's a quick fix and I'm really out of ideas. Although I might just leave it be if the pressure is steady when I get home, and just add that to the checklist going forward. I'm just at a loss as to why I didn't notice any bubbles from the pressure release to begin with

That's a good point about the starsan. I threw some into a spray bottle after cleaning the system, but soap would be just as easy.

 

[bob1852]

PSI drop like that on a refrigerated CO2 tank is perfectly normal.

 

[Sixmilecross]

Oh man I'd never even considered that. That should have been the first thing to come to mind. Though hoping I didn't just jinx myself

 

[mng8r]

The tank pressure dropping may not indicate a leak. Is the tank inside or outside the refrigerated unit? If it is inside, was the tank warm or at room temp when it read 800 and now that it's been in there awhile and cooled down, does it read 500-600? If so, this is most likely normal. Since the volume remains the same, as the temperature goes down, the pressure will too.

Ron

 

[Sixmilecross]

Yea I think that may be what it was. I feel like a dope for not even considering that to begin with.

 

[masonsjax]

Tank pressure gauge is nearly useless for co2. Since co2 is liquid under pressure, the gauge will show some high pressure until it's empty, then drop to zero.

Unhook all kegs and set the pressure to 30 psi or so. Close the tank valve and leave it sit overnight. If the low pressure gauge has not moved, you have no leaks in the system and can move on to checking keg poppits and o-rings. If the pressure has dropped, you can continue diagnosing. This method let's you discover leaks without wasting a whole tank doing so.

I highly recommend using 3/16" beer line and 1/4" barbs for everything both beer and gas. It's a snug fit where the clamps are just extra insurance, you're not relying on them to seal the connection. You probably need to change out the barbs on your regulator, but it's well worth the trouble, ask me how I know

 

[Sixmilecross]

Unhook all kegs and set the pressure to 30 psi or so. Close the tank valve and leave it sit overnight. If the low pressure gauge has not moved, you have no leaks in the system and can move on to checking keg poppits and o-rings. If the pressure has dropped, you can continue diagnosing. This method let's you discover leaks without wasting a whole tank doing so.

I may do this tonight just to be sure.

I highly recommend using 3/16" beer line and 1/4" barbs for everything both beer and gas. It's a snug fit where the clamps are just extra insurance, you're not relying on them to seal the connection. You probably need to change out the barbs on your regulator, but it's well worth the trouble, ask me how I know

So I have a hex nut at the end of the gas line that screws onto the wye, so no need for barbs. I'm pretty sure the tubing I have is all 3/16" although I think the one air tube I have from KegConnection may be 5/16".

Also, one of the things I noticed on the beer line I removed last night was that the worm clamp had dug into the tube and begun shaving strips off, so I'm curious if that may be where the air was getting into the beer line. Otherwise I'll have to double check the quick release. It can't be the poppet, otherwise changing to a second beer line wouldn't have helped.

Looking forward to getting everything nailed down once and for all. Even after the little headaches here and there, this still beats the hell out of bottling!

 

[masonsjax]

Air getting into the beer line might not be a leak. If the beer pours foamy, there could be a kink in the line or something else agitating the beer. If it pours smooth once the air pockets pass, your lines may be a bit warmer than they should be, causing some co2 to come out of solution. In that case, a small fan inside to circulate the air should solve the problem.

 

[Sixmilecross]

Don't think it's a temp issue, as switching beer lines fixed the issue. It may have been a kink in the line, but thought I recall seeing the line hanging free. The beer pours smooth after the air pockets pass, but then they form again. I'm guessing whichever side the air pocket forms on is the side with the issue - save me some time from checking the shank assembly. Will check again when I get home as it's time to keg my Winter Warmer (which I'm debating on whether to oak)

 

[raouliii]

..... and a wye with two swivel nuts (each joint has teflon tape). I closed the swivel nuts, turned the knob shut on the regulator,......

I'm not sure what you are considering a swivel nut.

Is your configuration something like this wye?:

with two of these valves?

If yes, all three threaded connections of the wye are NPT, and should have teflon tape.

However, the flare end of the valve and swivel nuts should NOT have teflon tape on the threads but this flare nylon washer:

 

[Sixmilecross]

My setup is just as you described. Teflon tape and washers are in their proper places. I think the tank issue was as AZ_IPA and mng8r said, just a result of the tank cooling in the keezer. Now I just need to get rid of the air pockets forming in one of the beer lines

 

[JuanMoore]

Don't think it's a temp issue, as switching beer lines fixed the issue. It may have been a kink in the line, but thought I recall seeing the line hanging free. The beer pours smooth after the air pockets pass, but then they form again. I'm guessing whichever side the air pocket forms on is the side with the issue - save me some time from checking the shank assembly.

There are really only two possible causes of this issue, and how fast the pockets of gas form in the lines can narrow it down to which one.

If you pour a pint or two, and the gas pockets form pretty much immediately, then you have a bad seal on the liquid side diptube o-ring, which is letting gas mix with the beer as it flows out of the keg. Check the o-ring and the surfaces that mate with it on either side.

If it takes an hour or more for the gas pockets to reform after pouring a pint or two, then the carbonation level of your beer doesn't match your serving pressure. When the equilibrium pressure of the carbonation level is higher than the serving pressure, the CO2 comes out of solution seeking equilibrium, and forms pockets of gas in the line. The two solutions to this are to degas the keg until the equilibrium pressure matches your serving pressure, or to increase the serving pressure until it matches the equilibrium pressure.

 

[Sixmilecross]

So I was able to fix the co2 leak and everything has been going great except I'm still having trouble with one of the taps - specifically what I think is the liquid side poppet. The beer has been pouring foamy and an air pocket seems to form almost immediately.

I've checked the post and the o-rings seem fine and I've tried switching connectors in case there was something wrong with the first, and still no fix. I've noticed that the poppet sits loose in the post but I don't think this is the issue as others have used similar posts with no problems.

My guess is that I need a new post but wanted to make sure there wasn't something I missed

 

[masonsjax]

Check the dip tube o-ring.

 

[JuanMoore]

Check the dip tube o-ring.

This.

Like I said in post #14, a bad seal on the dip tube o-ring is really the only possible cause for what you're describing.