The case of the ghost leak

[Howhownow]

I finished my new kegerator around September last year. It's a beautiful 40's Whirlpool/RCA that runs like a champ. This is my second kegerator build, so I learned a lot my first time around and my lines are much more organized, and nicely balanced.
I am having one ongoing issue that I can't seem to find pin down, and it's driving me to a bit of frustration: I have a slow gas leak somewhere. If I hook a fresh CO2 tank up at serving pressure, it takes about 2 weeks and the thing is dead, regardless of use. I've drained 3 tanks like this.
I appeal to your collective experience for help. In the spirit of working through this logically, I'll lay out the pertinent details, solutions I've already tried, and things I'm thinking or trying. This is unfortunately a tough one to test, because it costs me a full tank of CO2 each time.

Details:
- I run pin lock kegs
- I am currently keeping the regulator set to serving pressure, with the shutoff valve closed. I open it dailyish, or often during active serving to keep the kegs charged. This tells me the issue is not with the regulator or connection there.
- Run gas through a 3-way manifold, which only has 2 lines presently hooked up

Tried:
- Spray down everything in sight while hitting with high PSI's. No bubbles.
- Keg lube on every poppit, lid, and qd.
- Make sure my connections are all straight each time I attach a QD. (I've had a kegerator for years, this has never been the issue for me)

Thinking of:
- Nuclear option: tear down and rebuild whole gas side. I would REALLY prefer not to do this. My lines are run and organized nicely, and this would be a big PITA.
- Charging up each keg while empty and not in use. Issue is- how can I tell if it's losing SOME presure? Could I submerge it in the tub?
- New poppits. I'd like to narrow it down to a culprit keg before I do this.

What I'd like to try is a systematic approach to find the line/connection that is bad. I'm just not sure the best way to go about it...
HELP

Gas line runs behind the coil on the top of the unit, manifold is on the left, out of view. Can snap a picture if needed.

 

[UpstateMike]

Thinking of:
- Charging up each keg while empty and not in use. Issue is- how can I tell if it's losing SOME presure? Could I submerge it in the tub?

How about hooking up a keg pressure tester? Leave it overnight and see if the pressure drops. You can buy one here: Keg Pressure Tester

Or you can build one: Build a keg pressure tester

 

[Howhownow]

How about hooking up a keg pressure tester? Leave it overnight and see if the pressure drops. You can buy one here: Keg Pressure Tester

Or you can build one: Build a keg pressure tester

Very good info. I suspect that I have a bum keg that may be the culprit.
Thinking out loud: I would need to conduct this test on an empty keg, right? If it had liquid in it, some of the gas would go into solution and decrease pressure?

 

[Joseph503]

I ran into some leaky lines when I first built my keezer earlier this year. I ended up going through a 5# tank in a couple of days and found a leak on the backside of one of my connections. Thinking I had it resolved I hooked it all back up and ran through another 5# tank to find out it wasn't my connections, but my keg leaking.

What I would do is try to work systematically. Close all valves and check one section at a time slowly opening up each section, spraying everything down with soapy water or sanitizer solution. Make sure you're checking all of the backsides of your connections as well, use a small hand mirror if possible.
Try to remove all other ambient noises and unplug the kegerator, or other nearby electronics, etc so that you can focus on trying to hear those low-pitched whistles or whines of leaks.
If you think you're fairly certain none of your lines / connections are leaking, start to investigate the keg(s). Throw 15-20 psi into it, and disconnect it from the system (You could do this just before checking the lines as well). Spray down all of the connections (inlet, outlet, and main seal). Look, feel, and listen for leaks. If it seems to be air-tight let it sit a while under-pressure and check back later to be sure it's still holding. If it's not holding or it's questionable, replace all of the o-rings.

If you've done all of this and it's still a mystery, try cutting off a small section of gas line and re-seating / clamping your connections (given you have a little bit of gas line to spare). After all of this if it's still leaking, start to replace gas-lines and see it takes you.

Finding / resolving CO2 leaks is no fun and unfortunately you're going to go through a bit of gas trying to fix it. rdwhahb and work through it slowly and systematically.

I wish you the best of luck finding that leak.

EDIT: Regarding your question to find out if a keg is losing pressure: You could submerge it in a tub and watch for bubbles. You could also spray everything down to watch for bubbles. If you don't see anything either way here, then pump it with 15-20psi let it sit for a day, then hook it back up again at the same pressure. If you hear CO2 rushing in, then there is probably a leak.

 

[suckmyale]

If you have a bathroom scale (or a good kitchen one), you could weight the tank through-out the day to see if it is decreasing in weight. Maybe if you could switch it to grams that would be helpful.

Unfortunately you are only dealing with a smaller tank of Co2, so you might loose a little bit before you notice it.

Its hard to tell with the pics what you all have in your setup, but as you start closing things, and checking weight it might help pin-point things.

***Maybe we should add a thread, my newly filled tank just emptied in 2 days, cause I think it has happened to everyone.***

 

[splendidus]

I would leave the shutoff valve open and turn off all 3 valves on your manifold. Only turn them on when you are serving from the attached keg. This should localize the leak. In the worst case the tank goes dry in a couple weeks and you know the manifold (or manifold to regulator shutoff connections) is leaky. If this prevents the leak, you know it is in the lines to the keg or the kegs themselves. Additionally, if the kegged beer is actually carbonated fully, this will tell you which keg/line is leaky. You will know because every time you flip on that line at the manifold CO2 will be added to replace the CO2 that leaked out (since the CO2 levels in the liquid and in the headspace of a fully carbonated keg are in equilibrium, no CO2 would be added to a non-leaky keg). In this way you won't have to tear down all of your system nor will you waste more than 1 tank of CO2.

 

[Howhownow]

I think you are right. I am going to take a systematic approach.
I have the PSI cranked up to ~30, going into the manifold. The individual manifold shutoffs are off. I'll leave it like that, only opening to charge the kegs.
If I still have gas in a couple weeks, I'll open the manifold, but leave the QD's detached from the kegs. If I drain the tank then, I know I have at least one leak in the connections/lines from the manifold to the QD's. I'll re-seat all my gas connections.
If I still keep gas in the tank, it's the kegs. I'll deal with them using the suggestions above.

Thanks for all the help.

 

[Howhownow]

I did it! I found the bastard!
I had been systematically working my way through from my regulator down to my disconnects and kegs. The kegs all seemed to keep a good seal when pressurized and stored, so I was able to count that out. Manifold proved to be airtight.
It got down to my QD's and sure enough, when I left the gas open to one (unhooked from the keg) it drained the tank. Got a fresh CO2, and carried on like I had been. Yesterday I went to replace the QD, which I assumed was leaking through the pin that makes connection with the keg poppet. To check this theory, I dunked the whole thing into a pint glass of water with 30 PSI open behind it. Sure enough, it was leaking, but not from somewhere I ever imagined! The leak was coming from the connection to the gas line. I have the 1/4" MFL threaded QD's, so I put some thread tape on it and retorqued the barb. Back in the water- STILL LEAKING. I inspected it again, and realized the leak was coming from under where the barb was connected to the gas line, through the worm clamp! I moved the clamp closer to the end of the line, and torqued it as tight as a was comfortable with. Check again- LEAK GONE!
This leak was silent and slow, and would not show up even with careful spraying with the star-san bottle. I have had plenty of airtight connections even without a clamp on the line before. It had me truly frustrated. Hopefully that was my only issue, and I can start carbonating and serving my kegs like a normal person again!

Moral of the story: CLAMP YOUR HOSES, AND CLAMP THEM WELL!

 

[day_trippr]

That's one moral, but another with perhaps higher value is to dunk-test everything you can before putting it into service.

There were four different leaks in this assembly. None of them were due to poorly-clamped lines...

Cheers!

 

[The_Bishop]

Don't put tape on MFL connections. The seal has nothing to do with the threads, it's the tapered seat that seals.

 

[mrstevenund]

That's one moral, but another with perhaps higher value is to dunk-test everything you can before putting it into service.

There were four different leaks in this assembly. None of them were due to poorly-clamped lines...

Cheers!

Agree with this 100%. I'm currently fighting a CO2 leak that is my fault, and not a MFL Flair fitting. For the flairs, make sure you have nylon washers - http://www.homebrewing.org/14-Nylon-Flare-Washer_p_4043.html


My problem - I have a 4-way manifold and decided to a) put a post adapter on one side (http://www.homebrewing.org/Plug-Adapter-14-MPT-x-1932_p_4640.html) and b) to move the plug to the opposite side from day_trippr's picture above. I first tried taping it, but it would not seal and it was only visible when dunked under water. Now i'm working with pipe dope, and on my 3rd round with this stuff. Initially it looks like it is sealed, but wait 24 hours and small bubbles appear. Regulator is set to 40psi for the leak testing and I still have bubbles.

 

[The_Bishop]

Use this stuff:
http://www.rectorseal.com/index.php/rectorseal-no-5/

I use this for all sorts of plumbing. It seals every pipe thread I throw at it.

 

[mcgray8]

After replacing several lines over the years, the double ear clamps work the best! I wouls strongly encourage everyone to use them over the worm gear clamps.

 

[mrstevenund]

I picked up rectorseal when I switched to the dope - http://www.lowes.com/pd_44921-72720...l&pl=1&currentURL=?Ntt=rector+seal&facetInfo=

 

[dcrog]

I have a 2.5 lb. cylinder in my kegorator. Came with the Nostalgia box. It kept going through a bottle a month and I kept searching.

Finally found it on the regulator. The threaded stem coming from the bottle where it screwed into the reg. Very slow and had to leave the soapy water on it for a little while for the bubbles to start forming.

Unscrewing, left handed, and teflon taping cured it.

 

[mrstevenund]

3rd time is the charm for my manifold. Looks like it sealed. Only thing different was to buy a wire brush and clean the female threads good before the rectorseal.

I did see the top of one of my QDs has a bubble every 20 or so seconds when under water. I'll tear that down and add some keg lube to the oring inside. That would be another place to check.

 

[Howhownow]

I just picked up some of those flare washers, going to install them this week. So far everything is still sealing well...