Does my keg really have a gas leak? Not sure what to check next...

[Gilligan]

I can use some advice on chasing down a possible gas leak. This is a new to me, used keg that I refurbished and I'm now testing for leaks. I replaced both in/out valve stems, the o-rings on the gas and liquid tubes, the lid o-ring, and the pressure relief valve.

My test method for this keg, which is half full of water, is to pressurize it at 10-12 psi, disconnect both quick connect fittings and leave for 24 hours. The problem is that after 24 hours, there is not enough internal pressure to force any of the water out when I reconnect a hose to the liquid outbound fitting.

I put soapy water around the lid, the pressure relief valve, and the two in/out valve stems. There are no bubbles.

Is it possible that the pressurized CO2 in the keg dissolves in the water overnight and the inside/outside pressure equalizes? If not, what do you think i should do next to chase down the leak?

 

[Golddiggie]

Chances are, the water in the keg is absorbing the CO2 you're putting into it. As you stated at the end.

Try filling it when empty and checking the next day if it takes any more CO2 to get back to the same pressure level. You can also get one of the pressure testing ball lock setups (have one I bought years back).

Or, just pressurize it, dry around everything and spray down with StarSan solution and see if you get bubbles. IME, kegs will either leak, or not, pretty quickly. Ramp up the pressure to 20-30psi and you'll find ANY leaks a LOT faster. I'd trust that over the 'does it still push' test method.

 

[Tobor_8thMan]

I agree with Golddiggie, 24 hours at 10-12 psi is probably not enough to carbonate the water. What is the ambient temp of the keg. Is it at room temp? Is it at 38F or some other temp? Please consult a CO2 chart to properly carbonate.

When I slowly carbonate a whole keg at 10-12 psi it takes over 1 week!

 

[day_trippr]

Practically speaking, leak testing of kegs has to be done with empty kegs. Water will just slow down any observable issues at best.
If one really wants to test a keg, put the keg on 12 psi and stick the business end under water.

Why 12 psi? That's close to how it'll be used the most. Nobody runs kegs at 30 psi - which can only help to seal an otherwise dodgy keg...

Cheers!

 

[Gilligan]

Thanks, guys. I'm not carbonating water intentionally, I'm just testing for leaks at 70 degrees F. I drained out all the water and pressurized it to 25 lbs. I'll see if there's pressure left in it tomorrow. If it leaks out, I'll try day tripper's 12 lbs underwater test.

 

[Tobor_8thMan]

Please remember what day_tripper wrote "Nobody runs kegs at 30 psi - which can only help to seal an otherwise dodgy keg...". Same applies to 25 psi.

Now, I do originally seal the keg lid gasket with a shot of 30 psi and check everything for leaks, but then I dial the psi down the the desired carbonation level.

 

[Gilligan]

I know.... But I pressurized the empty keg before I read his post. He made a really good point there. I'll do the underwater test tomorrow anyway.

 

[Golddiggie]

IME, once the seat is sealed, as long as pressure remains the chances of it failing under 10-12psi is low. Not zero, but low.

I've gotten to use the model of pulling the lid up when sealing the keg, getting it as close to properly aligned as possible and then hitting it with ~10psi to get it to seal. I use ~10psi because I don't want to use up more CO2 than needed. I tend to use a small CO2 tank for this since I'm also transferring my beer with a CO2 push (from fermenter).

I've had other things (not kegs) fail to seal at higher pressures where they seal just fine at lower pressure levels. Not kegs, or beer related mind you.

I've yet to need to replace any pressure relief fittings on any of my kegs. If the one in the lid was bad enough to warrant replacement, what kind of shape was the rest of the lid in? I'd make damned sure you got that installed properly before going too far down any leak rabbit holes (if it doesn't hold pressure).

 

[Bobby_M]

With a vessel half full of liquid, new headspace pressure would drop approximately in half given some time. If you put 20psi in, it should only drop to 10, not zero. The best way to test for keg leaks is to leave it empty of liquid. Pressurize to whatever and spray all openings with soapy water and look for bubbles.

 

[Tobor_8thMan]

What Bobby_M said. It it a blast of 30psi to seat the lid. Then do the soap check. Don't forget to check the relief valve.

 

[bracconiere]

Practically speaking, leak testing of kegs has to be done with empty kegs. Water will just slow down any observable issues at best.
If one really wants to test a keg, put the keg on 12 psi and stick the business end under water.

empty would be best. but i was talk how to tell a keg was 'full' and it came to weight. get a $27 scale. pressurize the keg empty. put it on the scale and wait a day. but be sure to check it at the same time, the sun's gravity messes with them like weighing yourself and water does.