King Keg pressure leak or not?

[ScoobyDoo]

I purchased a new King Keg the other week and fitted a pressure gauge, currently have one with a brew in already so wanted to start a second
Brewed a woodfordes nog and primmed with sugar
After 2 days no pressure, used the soap test and found the s30 valve was leaking
Unscrewed the cap and replaced the s30 and resealed.
After 2 futher days pressure rose to 4 psi

After day 5 pressure started to fall back and dropped to 2psi, tightened cap and injected some co2 upto 5 psi
I immediately heard a hiss from the cap, tried tightening again but still hissed and pressure dropped to 0

Unscrewed cap, replaced rubber seal , ptfe tape on barrel threads and resealed and put co2 in, pressure was at 5psi and no hissing
4hrs later pressure has dropped to 4.5 psi
Tried the soap test and no leaks on s30, gauge and no hissing

Just wondering if the cap is still leaking or is the beer absorbing the co2? and if its absorbing how much will it take and drop my pressure to before stabilising?
Thanks.

[alexlark]

Just a thought, make sure you don't over tighten the cap and deform the seal. I made this mistake in the past!

[Horden Hillbilly]

In addition to alexlark's good advice, give the large O ring what fits into the cap a smear of petroleum jelly before fitting it, that will help to ensure a good seal. It is also normal for the brew to absorb the co2, especially if there's a drop in the room temperature. It's also a wise move to change all 3 seals on a new S30 valve imo. You don't know how long they have been on the valve & they can stretch over time.

[ScoobyDoo]

Thanks for the advice, ive re seated the cap again but still having pressure drop, very slow over 12hrs.
Might have to dump the brew out in the end and try and see what the issue is..

Whats the best way to test for pressure leaks without the brew being in there?. Fill with water and inject co2 or just inject co2 with no water?

[Bad 'Ed]

I'd do it with no water in as there's no chance for the gas to be absorbed into anything and you won't really be using any more of your CO2.

There's no leak elsewhere on the barrel is there? One your other one is empty you could swap caps and make sure it is an issue with something in the first cap.

[ScoobyDoo]

Thanks. Ive purchased a new cap and tried that but same issue with the leak. I did feel the top of the barrel and it seemed smooth but thinking it could need sanding down, its worth a try and then ill try the gas test with no water in it..
The leak is very slow, probably loosing .5psi over 12+ hrs.

[motco]

Thread revival! I've been using King Kegs (and the Boots brown one with the same cap) for donkey's years and it always seems hit and miss as to whether I can dispense a full barrel without adding CO2 or not I never prime as it delays dispensing time and compromises clarity. As I have a pub size cylinder providing the gas through the S30 valve, I haven't bothered too much about having to add gas occasionally. My brewery in in my basement and it hardly ever gets warmer than 15ºC and doesn't move up or down much in temperature. Recently, though my brews have been flat and I have needed to put more gas on than I would wish. On a thread somewhere a fellow quaffer suggested that a square section cap seal would work better than a round section because it has a larger contact area. Instinctively i feel that a round section can be forced to conform to irregularities in the barrel sealing surface than square, but I've ordered one anyway to check.
I always nip the cap down with a cap spanner and always apply Vaseline to the threads and seal. Yesterday I shoved in a blast of CO2 and I could hear gas escaping. A further nip down of the cap stopped it but I am suspicious of the keg rim surface smoothness. Ideally the edge needs a sharp blade to skim off a sliver of the slightly rough edge and I have done this with a small necked barrel using a woodworking plane to good effect. However I am unsure that it would work with a larger diameter neck without risking making the plane of the neck surface out of 'level' when the cap is screwed down leaving a gap that no seal could accommodate. Sandpapering is an option but HDPE doesn't sand well due to its inherent softness, but again I am willing to try. People criticise the King Kegs for quality issues, but I have found the bottom tap type is generally pretty good - cap sealing notwithstanding. Corneys are all very well but I want a 40 pint keg not the lesser volume of the Corney.



An old shot of the brewery before the pub cylinder and second King Keg. Sodastream dropping that cylinder prompted the change of gas source.



Cheers!

[themadhippy]

However I am unsure that it would work with a larger diameter neck without risking making the plane of the neck surface out of 'level' when the cap is screwed down leaving a gap that no seal could accommodate. Sandpapering is an option but HDPE doesn't sand well due to its inherent softness, but again I am willing to try.

dont bring the paper to the job,bring the job to the paper.
Put your fine emery cloth on a flat surface,put the neck of the barrel onto the paper ,stand on the paper to stop it spinning and rotate the barrel left and right whilst pushing it down onto the paper.

[guypettigrew]

Two 2 of the 3 King Kegs I use are decades old as well! One split at the base so had to be replaced. About a year or so ago they started leaking gas from the cap seals. Exactly the same as you describe-squirt some gas in and some comes back out again through the thread/cap.

The 'O' seals were all replaced with the square section ones. No more gas leaks. Mind you, the same may have happened if they'd been replaced with brand new 'O' seals!

As an aside, you might want to think about fitting these instead of the drum taps. Less froth and easier to control.

Guy

[motco]

guypettigrew, thanks for the link. If My efforts to seal off leaks are successful I might need some way to reduce foaming or I'll be drinking halves in pint glasses!

The madhippy, than you too for your reply. I had thought that a sheet of emery on a board larger than the neck diameter would help maintain a true plane, but I did not think of inverting the barrel on to the abrasive sheet. Not only does that solve the need for a moveable plane on which to fasten the abrasive, but it stops debris falling into the barrel.

Reports to follow.

[motco]

I haven't found the round section or the square section seals to be significantly different from each other in performance. Instinctively I feel that the round section is probably better because of its inherently more compliant nature. As long as any width of 'footprint' is making contact it will seal, so if some areas around the annulus are making contact before others, it is easier to compress (progressively) a round section locally, than a square section. The latter will be fiercely resistant to compression as soon as it makes contact so expecting it to allow other areas to be able to approach contact is difficult to imagine. For a square section to seal the sealing surfaces MUST be perfectly parallel with each other - unlikely with a cottage industry moulding shop I suspect. It's doubtful whether precision trimming is employed for a low-build product compared with, say, a tens of thousands per annum item.