Do I have a CO2 Leak?

I just started kegging and am concerned that I may have a co2 leak. 2 weeks ago I put my first keg into my kegerator and the regulator was reading just over/at the 600 psi line, or above the red. I keep my regular/co2 tank inside my kegerator. Pressure remained constant for the first keg. I added a second keg to the system 5 days ago and for the first couple of days it appearted the pressure was also pretty much constant. I checked it yesterday and it had dropped below the red line and I checked again today and it's after dropping a little more, now at about 425. My fridge temperature is at 41 degrees.

To carb my kegs I put them at 30 psi for 24 hours and then back to serving at around 10-11psi. I would guestimate I have gone through about 1/3 to 1/2 of the first keg and about 6 glasses out of the second. The only other co2 I used would have been to seal and purge the kegs after I sealed them.

Here's a picture where my regulator pressure is now. Should I be worried?

[IMG="http://www.flickr.com/photos/92283963@N03/8387153433/"]

You most certainly shouldn't be concerned. PV=nRT... on other words, as temperature (T) goes down, so does pressure (P) and volume (V). I had the same worry when I started kegging since I used to keep my CO2 tank inside the fridge.

But just to be sure take a spray bottle with some sanitizer solution in it and spray areas where CO2 could possibly leak: gas quick connect, keg lid, any point that gas line connects to something else. It will help you see if anything is leaking as it will produce a bunch of bubbles in the liquid. But I think it's just because you're keeping the CO2 tank in your fridge.

Hope that helps

Thanks for the reassuring response I guess I'll leave it for another few days and see how it goes. When I put the second keg in I put soapy water on the keg lid/posts and line and didn't not have any leaks but I did not check the lines back to the manifold and regulator as I figured they were good as they came pre-assembled.

I don't plan on any more beers tonight - could change though , should I expect any drop in pressure by tomorrow or should it remain fairly constant at that pressure?

I've read other threads where people are getting 5-8 kegs out of a 5lb tank, I hope to get at least 5 as co2 isn't cheap for me - was $41 to fill the tank last time!

I've often said (only half jokingly) that the best way to deal with the high pressure gauge is to cover it with duct tape.

The reason is that it's totally pressure/temperature dependent. Right now, my completely full 5 pound tank reads 750 psi. If it put it in the fridge, it'll go lower. And it will stay where it is until it's almost empty, and then go to 0 in an hour!

The reason is that co2 is a liquid, but dispensed as a gas. The high pressure gauge is useless, unless you want confirmation that the tank is empty. When you fill the tank, it's given to you by weight. So, a 5# tank should hold 5#s of gas. If you weigh your tank, without the regulator, and subtract the tare weight stamped on the side, then you'll know how much gas you have. The high pressure gauge isn't useful at all for that.

$41 to fill a 5lb tank sounds kind of high, I just filled my new one for $11. You might want to check around.

I checked my gauge again this morning before leaving for work and it doesn't appear to have moved overnight - what you've guys said appears true. I'll just relax and have a beer.

Hockey is back on Saturday night, habs vs leafs, I'd say I'll be having more than one

Reno_eNVy said:

You most certainly shouldn't be concerned. PV=nRT... on other words, as temperature (T) goes down, so does pressure (P) and volume (V).

Click to expand...

Not to nitpick, but: since this is a gas/liquid system, the ideal gas law is irrelevant when looking at the total mixture. If you had a cylinder with pure gas in it (once you run out of liquid CO2), the pressure will fluctuate linearly with temperature as you described.

When there's liquid present, the fluctuations are due to changes in the vapor pressure of liquid CO2 (vapor/liquid equilibrium) with temperature, not the gas expanding/contracting.

http://en.wikipedia.org/wiki/Carbon_dioxide_data#Liquid.2Fvapor_equilibrium_thermodynamic_data

Attached is a quick plot I put together using the data from Wikipedia. As you can see, it's not linear.

I checked it again this evening and it has dropped further and sits at the 400psi mark. The fridge is no colder so I'm not really sure what would explain this. Back to thinking there is a leak. I'm gonna dry some soap water this evening to see if I find anything.

Check it with some soapy water or spritzing with StarSan can work. The pressure should drop when placed in the fridge, but should stablilize. If it keeps going down over several days, there is something else going on. From your original post it sounds like it has been at cold temp for two weeks, it should have evened out after a day or so. I would begin by checking the lines and the connections at the newly added keg, since your problems seemed to start after the addition of that keg. If that doesn't reveal the problem, start checking the other areas.

zachattack said:

Not to nitpick, but: since this is a gas/liquid system, the ideal gas law is irrelevant when looking at the total mixture.

Click to expand...

Ah yup... yup, ya got me

I think you DO have a leak. My 5 LBS CO2 tank usually lasts me for about two months if I pressurize beers from the tank or 3 to 6 months if I use only naturally primed and carbonated kegs. I used to have leaks but they stopped after I put all new O'rings and seals on all my kegs and started using the keg lube. USE the KEG LUBE.
BTW, $41 to fill a 5 lbs CO2 tank is ridiculously expensive. I pay $11 a tank. Find a new place to fill your tank.

Shooter said:

Check it with some soapy water or spritzing with StarSan can work.

Click to expand...

That's a good idea.

Also if the tank is filled by someone who has no clue (like most places that sell beer) they do not fill it correctly. The best place to have one filled is a welding shop or a gas supplier like air gas etc. The reason is the tank should not be hot when filling and should really be purged first. The beer places do not weigh it and you almost always end up with just the gas and not the liquid so it does not last nearly as long.

I had my tank filled at Praxair...it was the first time it was filled, don't know if that makes a difference in the cost but I agree $41 is expensive. I will check around.

I think I just found a small leak around the poppet on the gas in line on the first keg I tapped. I checked the 2nd keg first thinking that's where the problem would lie but could find not find anything. I disconnected the gas line and checked the gas post as well. I then checked the 1st keg and found at the top of the poppet for the gas there was a very subtle bubbling...very small, hardly noticeable at a glance but was definitely there and different from the other keg, and when I relieved all the pressure from the keg it stopped. I had another spare poppet, not new, which I put on and pressurized the keg to 20psi and there was no bubbling.

So does I sound like I might have caught the culprit? Over the course of all this my regulator now reads just shy of the 400 mark...slightly lower again. I'm getting worried I'm running out so I think I will take it after the weekend and get it refilled, or at least check it every morning and evening to keep an eye on it.

I wouldn't suspect a leaky poppet to be the problem. The poppet is going to be pushed in when it's connected to the system anyway. The leak could be somewhere in the disconnect head, around the base of one of the posts, CO2 in or liquid out, the lid seal or somwhere in the line connections or up towards the regulator. There are a lot of options, but a poppet that doesn't seal when nothing is connected to it shouldn't be causing you to lose CO2 like this.

So what I did last night was turn off the gas to the kegs at the manifold to rule out leaks beyond that point. Seems the gas dropped slighly over night, I will check again after work.

When connecting the co2 tank to the regulator, is it recommended to use thread tape? I didn't but I can see it was used on all parts of the regulator. Also, when I connected the regulator there was a hard plastic white gasket/washer that I suspected went in between the reguator and the tank nozzle, which I did. Would keg lube on that help. Also, how tight should I put it? I believe I just put it tight by hand, as tight as I could but no wrenches or anything.

Part of me is starting to think that's where I might be losing the gas.

Yep no lube needed on the washer but it should be tightened down snug with a wrench. I bought a large cresent wrench for that and another regular wrench that fits the keg posts. I use them a lot when cleaning kegs and switching out tanks.

NLBrewer said:

Also, how tight should I put it? I believe I just put it tight by hand, as tight as I could but no wrenches or anything.

Part of me is starting to think that's where I might be losing the gas.

Click to expand...

You want to give it a good snug with a wrench, but don't go overboard or you'll just crush the washer. I think that this is where the leak is coming from.

No thread tape on CGA fittings (save it for NPT), and you don't need to lube the washer.

Thanks guys, I'll report back tonight when I check things out. Funny, when I received the parts for my kegerator there was a wrench included but I had no idea what it was for so, as it didn't seem to fit anything, I just put it aside and forgot about it. Never thought to try it on the regulator

I've blown 2 20# tanks due to loose hoses - if you're using the standard 1/4" soda keg quick disconnect (QD) and a line bigger than 1/4", you may run into problems. Most gas lines i see run between 5/16 and 3/8, and the barbs on the manifolds are about the same size. Those just won't always seal correctly to a 1/4" QD barb. The more kegs you have, the bigger your problem will be.

If that could be your problem, there are two ways to fix it.

#1 - use a 1/4" air line, and heat the end you're connecting to the manifold in boiling water for 20-30 seconds. The line will get soft enough to fit on even a 5/8" barb (wear gloves - if your hand slips it'll hurt).

For illustration purposes only - flare QD: http://morebeer.com/view_product/18270/102293/Ball_Lock_Gas_In_-_Flare
1/4" nut with barb: http://morebeer.com/view_product/18264

#2 - Switch to the 1/4" flare (screw) QDs and a 1/4" nut with a 5/16" or 3/8" barb. Use the "soak in hot water" method to get your hoses on - if you have to heat up your lines to fit them on, then it's going to be really hard to get a leak once they get cold. Just make sure to use a tubing screw clamp on the end as well.

Finally, if you think you'll need o-rings in the future, check out this post from home brew finds. I ended up getting a full set of bulk rings and am very happy I did. Nothing like losing the internal o-ring in your quick disconnect (was cleaning) on kegging day and realizing "oh wait, i have 50 more!"
http://www.homebrewfinds.com/2011/08/keg-o-rings-v2.html

Hope that helps, and hopefully your problem is an easier fix. It could just be lose connections to the keg. If it's ball lock, you can pick up cheap deep sockets from an automotive place like Advance auto parts for $3-$5 a piece. Don't pay the $12.00 from a brewing store unless you have to.

Well I think I found the leak, or one of the leaks, where the regulator screws onto the tank. I put some soapy water there and had a bubble form on the edge. It couldn't have been a fast leak as you really couldn't hear anything and the bubble did not pop quickly but I guess it's been a slow leak all long. Hopefully I can get through the weekend, if it stays stable I should be good! Thanks for everyone's help and suggestions, hopefully this is the end of the matter.

I would definitely take the time to remove the regulator from the tank and make sure there's a gasket tucked inside the regulator coupler...

Cheers!

day_trippr said:

I would definitely take the time to remove the regulator from the tank and make sure there's a gasket tucked inside the regulator coupler...

Cheers!

Click to expand...

Forgot about that one - whoops. Had that problem too.

Check the *type* of washer if you have one. Rubber washers are single use and won't prevent a leak over time. Nylon and Teflon washers are multi use. They're hard, ~1/8" thick, and white or clear. Your gas supplier should be able to sell you one cheaply.

Side note - the regulator-to-tank connection i have is intended to seal at the washer and isn't meant for Teflon tape.

Another note here is that the taprite uses a quad seal o-ring NOT the teflon (may work though)

I have the teflon type washer.

Looks like I may have solved it. The gas pressure, while low, has been steady at 250psi for the last 36 hours. Not sure what is left in the tank but hopefully I'll get to finish at least one keg off it. I also picked up some Masters Leak Detector in the plumbing department at Home Depot, when I refill my tank I'm going to verify all the joins again.