Better quality King keg cap

[Petefin]

Hi Guys,
Does anyone know of a manufacturer who makes a better than original King keg cap?
Having a nightmare trying to get a seal, tried everything!
The cap is now jumping the threads if I tighten it too much.
I am using a square O ring, have made sure the barrel lip is dead flat. Tried ptfe tape, going to try liquid ptfe next but not optimistic. I am an engineer and rarely beaten by such a thing, but I suspect I'm trying to "polish a t**d".
Any ideas? A better quality cap is my next plan, if I can get one.
Also think the O rings, round and square are a little too hard to seal properly, we are only talking 15psi max, a softer material would be better.

Cheers, Pete

 

[foxy]

Hi Guys,
Does anyone know of a manufacturer who makes a better than original King keg cap?
Having a nightmare trying to get a seal, tried everything!
The cap is now jumping the threads if I tighten it too much.
I am using a square O ring, have made sure the barrel lip is dead flat. Tried ptfe tape, going to try liquid ptfe next but not optimistic. I am an engineer and rarely beaten by such a thing, but I suspect I'm trying to "polish a t**d".
Any ideas? A better quality cap is my next plan, if I can get one.
Also think the O rings, round and square are a little too hard to seal properly, we are only talking 15psi max, a softer material would be better.

Cheers, Pete

I am really surprised to read so many complaints about the King Keg caps. how can it be a pressure vessel with such poor manufacturing.
I have mentioned before that the cubes with a tap are a cheap and ideal alternative (not the jerry can with a tap for some reason the tap gets knocked out fairly easily) I have used the cube as a cask, even as a pressure fermenter and pressure tested the cube to 26 PSI.
You can ferment in one and transfer oxygen free to a serving cube.

 

[Buffers brewery]

Sounds odd! I have a couple of KKs and the cap is a loose fit on the barrel thread but not so loose that the thread “jumps”. Stupid question.. have you checked for leak at the rubber band pressure relief valve. Have you checked there is no leak from the non-return valve inside the cap (unlikely but you never know). I don’t like the KK cap arrangement and am experimenting to see if I can improve it. Don’t hold your breath!

 

[Graz]

Given up on mine. Got 5 corny kegs now. They don't leak

 

[Petefin]

Hi Buffers Brewery,
I have a guage and a 15 psi pressure relief valve fitted to the cap along with a schrader valve fitted for pressure testing. I have blanked off the original pressure relief valve. All leak checked with no leaks whatsoever.
The leak is definitely the cap to barrel seal.
I have seen red and green caps for sale, are they any better or out of the same mold with a different colour of plastic?

Pete

 

[Clint]

I recon you get good barrels and rubbish ones. Good ones you can fettle to get them to behave the rubbish ones are just...rubbish...and should be driven over then burnt.

 

[Buffers brewery]

Hi Buffers Brewery,
I have a guage and a 15 psi pressure relief valve fitted to the cap along with a schrader valve fitted for pressure testing. I have blanked off the original pressure relief valve. All leak checked with no leaks whatsoever.
The leak is definitely the cap to barrel seal.
I have seen red and green caps for sale, are they any better or out of the same mold with a different colour of plastic?

Pete

I have no idea of the significance of the different colours. I agree with @Clint a bit in as much as I would expect an injection moulding (cap) should be more consistent dimensionally than a blow moulding (barrel). Can I ask how you flattened the barrel sealing face?

 

[Petefin]

Hi Buffers Brewery,
Firstly, I fitted a square section O ring to the cap making sure it was seated correctly. I then got an engineer's paint marking pen and coated the surface of the O ring. The cap was fitted, screwing it down until it just contacted the barrel lip. I removed the cap, then using a very small engineer's surface plate (very flat!) with a sheet of fine emery paper on it, rotated the plate and emery, keeping a bit of pressure on the plate where the paint showed the high spot on the barrel lip. I repeated this process until I was getting an even paint mark round the entire lip. Probably only removing .5mm off the lip or less.
This way I was ensuring the lip was mating perfectly with the seal and there was no imperfections or leak routes on the barrel lip.
O ring was then removed, coated in vasalene and refitted. I then filled the barrel up to 95% with water and pressurised with air via the valve. The small volume of air in the barrel would show a leak quickly. It did
The pressure relief valve goes off over 15psi, so I only pressurised the barrel to 10psi. Not a fast leek but still a leak.

My other barrel that has the same issue and a new batch of beer in it (I thought it was OK) has just been re-primed, but this time I have put a run of liquid ptfe on both sides of the square section O ring.
Just hope I haven't contaminated the batch by opening it up to the atmosphere again, but I kept everything clean and was quick!

Appart from new, better caps, can't think of anything else to try. Time will tell if the ptfe works. Might be difficult getting the cap off though?

I know I should have invested in Corny kegs, but I'm new to this and spent £100 on two barrels thinking my engineering skills would enable me to sort out the barrels.
I know, before someone tells me; "buy cheep, buy twice! “

Pete

 

[Dean1674]

Hi Guys,
Does anyone know of a manufacturer who makes a better than original King keg cap?
Having a nightmare trying to get a seal, tried everything!
The cap is now jumping the threads if I tighten it too much.
I am using a square O ring, have made sure the barrel lip is dead flat. Tried ptfe tape, going to try liquid ptfe next but not optimistic. I am an engineer and rarely beaten by such a thing, but I suspect I'm trying to "polish a t**d".
Any ideas? A better quality cap is my next plan, if I can get one.
Also think the O rings, round and square are a little too hard to seal properly, we are only talking 15psi max, a softer material would be better.

Cheers, Pete

Could try the balliihoo king keg caps, I’ve got 3 of them , and they have the square o ring seals . Never had any trouble .

 

[Petefin]

Hi Dean,

That's an option if they will sell me caps with no hardware, gets expensive for an experiment otherwise.

Pete

 

[Buffers brewery]

Hi Buffers Brewery,
Firstly, I fitted a square section O ring to the cap making sure it was seated correctly. I then got an engineer's paint marking pen and coated the surface of the O ring. The cap was fitted, screwing it down until it just contacted the barrel lip. I removed the cap, then using a very small engineer's surface plate (very flat!) with a sheet of fine emery paper on it, rotated the plate and emery, keeping a bit of pressure on the plate where the paint showed the high spot on the barrel lip. I repeated this process until I was getting an even paint mark round the entire lip. Probably only removing .5mm off the lip or less.
This way I was ensuring the lip was mating perfectly with the seal and there was no imperfections or leak routes on the barrel lip.
O ring was then removed, coated in vasalene and refitted. I then filled the barrel up to 95% with water and pressurised with air via the valve. The small volume of air in the barrel would show a leak quickly. It did
The pressure relief valve goes off over 15psi, so I only pressurised the barrel to 10psi. Not a fast leek but still a leak.

My other barrel that has the same issue and a new batch of beer in it (I thought it was OK) has just been re-primed, but this time I have put a run of liquid ptfe on both sides of the square section O ring.
Just hope I haven't contaminated the batch by opening it up to the atmosphere again, but I kept everything clean and was quick!

Appart from new, better caps, can't think of anything else to try. Time will tell if the ptfe works. Might be difficult getting the cap off though?

I know I should have invested in Corny kegs, but I'm new to this and spent £100 on two barrels thinking my engineering skills would enable me to sort out the barrels.
I know, before someone tells me; "buy cheep, buy twice! “

Pete

Sounds like a pretty thorough flattening job! Did you check (I know you did) the “o” ring recess surface on the underside of the cap? If you’ve sprayed everything liberally with soapy water, left it for 10 minutes and can’t identify where the leak is, the only other thing that I can think of is the neck face and screw cap face are on the squiff (technical term) to each other so there’s not enough pressure on one side to seal. I know you got an even paint mark showing the face was flat, but that doesn’t indicate how much force is being applied around the seal, from one side to the other. No idea how to fix that if it is the problem

 

[Clint]

I done mine with a keen eye and one of Mrs Clint's nail file thingies...no wonder it's crap!

 

[kelper]

Is it a genuine King Keg? I lube the o-ring and threads with vaseline or food-grade grease and tighten it with one hand. Could you be overtightening it?
Ballihoo sell their version of a 4" cap with a schrader valve fitted. You have to fit your old S-30 pin valve. You can use a car tyre pump to pressure test. I fitted square o-rings but I'm not sure they are really necessary. I've never had the cap itself leak.

https://www.balliihoo.co.uk/barrels-buckets/barrels-accessories

 

[Petefin]

Hi Kelper,
It is a genuine King keg. I have tried just hand tight to as tight as I can get it and everything I between, still leaks and that's with the square O ring.
After everything I've tried, I'm down to liquid ptfe or a better quality cap.
Currently trying out the ptfe, I'll report back the results. Guage showing a little pressure this morning after a re-prime yesterday.

Cheers, Pete

 

[Buffers brewery]

I done mine with a keen eye and one of Mrs Clint's nail file thingies...no wonder it's crap!

Hey @Clint I’ve just posted a short vid showing how I flattened my lip . You might be able to recover yours.

 

[kelper]

Are you 100% it's leaking past the thread and not through the pin valve?

 

[Shipstone]

I am really surprised to read so many complaints about the King Keg caps. how can it be a pressure vessel with such poor manufacturing.
I have mentioned before that the cubes with a tap are a cheap and ideal alternative (not the jerry can with a tap for some reason the tap gets knocked out fairly easily) I have used the cube as a cask, even as a pressure fermenter and pressure tested the cube to 26 PSI.
You can ferment in one and transfer oxygen free to a serving cube.
View attachment 24471

View attachment 24469

Where do you get the cubes from it looks a perfect alternative.Thanks

 

[Petefin]

Hi Kelper,

Ifyou have a look at my photo on an earlier post, you will see my modified cap. The original pressure relief valve has been blanked off and a professional 15psi relief valve fitted with a guage and O ring seal in the base. A schrader valve is also fitted for leak testing. The entire setup has been leak tested at 14 psi and is sound. That leaves the cap to barrel seal. Currently looking at Fabricating a square seal out of a softer rubber, will let you know how that goes.

Pete

 

[Clint]

Last time I gassed mine I think it was leaking from round the valve locking nut, which I tightened but never seemed to work...

 

[Petefin]

Hi Clint,
I think the route cause of the leak is too hard a seal, be it a round or square section O ring. I have the kit for fabricating square section O rings from various flat rubber or silicon sheet.
So the experimenting goes on.
As a maintenance engineer for the last 45 years, I will not be beaten by this!
Will report back progress

Cheers, Pete