Better quality King keg cap

[Buffers brewery]

Hi Buffers Brewery,

Would be most interested in seeing your new cap. You have certainly got me thinking, a large diameter flat O ring and a flat stainless steel plate with my valves and guage fitted. A steel two piece steel band bolted to the bottom of the threads on the barrel with six or eight vertical 6mm holes tapped in them. Screws through the plate into the collar. The screws could be tightened to equally compress the gasket. Now that would work.
I am an engineer in a food factory with lots of stainless steel and a lathe big enough to hold something as big as a cap.
Sounds like my next project?
Let's see the photos Buffers Brewery and thanks for the inspiration

Cheers, Pete

Spot on @Petefin but I’ve used aluminium rather than stainless steel as I only have a hand drill, hacksaw and files at my disposal. It’s not finished yet but this is what I’ve done...

3/8 inch aluminium plate slips over barrel threads. M6 coach bolts loose fit. Going to thread ring M8 and secure bolts so they don’t fall out when you lift the ring off

Cut the top off a cap so that when it’s fitted the barrel lip stands proud of the top face.

Fitted a jubilee clip to hold the threaded bit in place.

The top is a piece of aluminium fitted on the underside with a neoprene rubber gasket.

Finally held in place and clamped down with wing nuts.

Just got to fit the HB valve fitting and there you have it. The Buffers Brewery Barrel Bung!

 

[Racinsnake]

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

I haven’t read the full thread but I experienced a similar problem. I made a real hash of flattening the neck and the only way I could make the barrel air tight again was to use two O rings.

 

[Racinsnake]

I think we were both typing at the same time Buffer!
Your last post makes my last comment a bit redundant

 

[Buffers brewery]

I think we were both typing at the same time Buffer!
Your last post makes my last comment a bit redundant

If it works, it’s a quicker and easier solution than mine!

 

[Buffers brewery]

How much did you sand off the neck of your King Keg trying to get it flat? This is one of my King Kegs fully screwed down and wrenched with a cap spanner - still a good 5mm of clearance.

View attachment 24610

Didn’t explain myself well. If you look inside the cap, the thread terminates just above the recess where the o ring sits. There’s a slight land that if the barrel neck outer diameter is a bit on the large side will hit that land and you won’t be able to tighten it anymore.

I tested this theory out by removing the seal and putting a couple of gobs of vaseline in the groove. When I tightened the cap and then removed it the vaseline was untouched. I reduced the outer diameter of the barrel neck using a detail sander and retested. The cap screwed down and when removed the vaseline had completely squidged out of the seal groove.

 

[Hazelwood Brewery]

Didn’t explain myself well. If you look inside the cap, the thread terminates just above the recess where the o ring sits. There’s a slight land that if the barrel neck outer diameter is a bit on the large side will hit that land and you won’t be able to tighten it anymore.View attachment 24615
I tested this theory out by removing the seal and putting a couple of gobs of vaseline in the groove. When I tightened the cap and then removed it the vaseline was untouched. I reduced the outer diameter of the barrel neck using a detail sander and retested. The cap screwed down and when removed the vaseline had completely squidged out of the seal groove.

Got it!

 

[Jules61]

I had exactly the same problem and solved it by wrapping a few turns of plumbers PTFE tape around the threads. Now holds pressure perfectly

 

[Hazelwood Brewery]

Didn’t explain myself well. If you look inside the cap, the thread terminates just above the recess where the o ring sits. There’s a slight land that if the barrel neck outer diameter is a bit on the large side will hit that land and you won’t be able to tighten it anymore.View attachment 24615
I tested this theory out by removing the seal and putting a couple of gobs of vaseline in the groove. When I tightened the cap and then removed it the vaseline was untouched. I reduced the outer diameter of the barrel neck using a detail sander and retested. The cap screwed down and when removed the vaseline had completely squidged out of the seal groove.

Good spot. Just checked mine and with the original round-profile seal, the seal stands proud of that edge. I can imagine if you are using a square profile seal it will need to be around 5mm thick.

Also, if you take great care to sand the rim smooth and flat you’re probably creating a beautifully square edge on the rim and making it more likely the rim will snag! If you’re going to sand the rim at all, you need to be creating a slightly chamfered outer edge.

 

[stevey]

If your king keg leaks, send it back and let them know what a pile of crap they are. Save your money and buy cornies instead. You can fit the valves for the gas capsules and use them in exactly the same way as your crappy plastic kegs, and they are about the same price as the (invented by satan) top tap king kegs.

p.s buffer, you must be an engineer with too much time on your hands. Furloughed maybe?

 

[Buffers brewery]

If your king keg leaks, send it back and let them know what a pile of crap they are. Save your money and buy cornies instead. You can fit the valves for the gas capsules and use them in exactly the same way as your crappy plastic kegs, and they are about the same price as the (invented by satan) top tap king kegs.

p.s buffer, you must be an engineer with too much time on your hands. Furloughed maybe?

Retired. Can never have too much time on your hands.

 

[Buffers brewery]

Good spot. Just checked mine and with the original round-profile seal, the seal stands proud of that edge. I can imagine if you are using a square profile seal it will need to be around 5mm thick.

Also, if you take great care to sand the rim smooth and flat you’re probably creating a beautifully square edge on the rim and making it more likely the rim will snag! If you’re going to sand the rim at all, you need to be creating a slightly chamfered outer edge.

When I checked mine (the one in the pic) there wasn’t a great deal of height difference between the land and the top of the round seal. I reckon less than a millimetre measured with my verniers and unsteady hand. Your right about the nice square edge as well thumb

 

[Petefin]

Hi Buffers Brewery,
I love your mod, it has given me a few good ideas as well. I like the cut cap held with a jubilee clip, much easier than a split clamp. The wing nuts are also a good idea. I'll get to work on mine next weekend. Got house eves to paint first

Cheers, Pete

 

[Petefin]

New cap arrangement sorted.
I cut the top off the original cap, cut out 3mm to tighten threads and put lock wire round the old cap to keep tight. Then machined up the parts as per the photos.
I filled the barrel up to the neck with water and pressure tested at 12psi. With such a small air volume left, any leak would show up quickly, but no leaks found. I made two, so both of my barrels will be good to go.
Thank you Buffers Brewery for the inspiration

Cheers, Pete

 

[Buffers brewery]

New cap arrangement sorted.
I cut the top off the original cap, cut out 3mm to tighten threads and put lock wire round the old cap to keep tight. Then machined up the parts as per the photos.
I filled the barrel up to the neck with water and pressure tested at 12psi. With such a small air volume left, any leak would show up quickly, but no leaks found. I made two, so both of my barrels will be good to go.
Thank you Buffers Brewery for the inspiration

Cheers, Pete

You’re welcome @Petefin . Very nice job. You obviously have access to some machine tools! I’m currently using my time to make an all plastic version. Watch this space
Oh, and this my prototype in use with my keg of Yorkshire bitter..

 

[Perrin_Abara]

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

hi, did you sort this problem out in the end, I'm having similar trouble. I haven't gone as far into the remedies as you so far though

 

[Buffers brewery]

Both @Petefin and I gave up on the King Keg cap and made our own. You can see his in this post #73. You can see my approach here...
https://www.thehomebrewforum.co.uk/threads/buffers-brewery-pressure-barrel-“bung”.86949/FYI, 2 or 3 other members use my caps with their King Kegs as they wanted to replace the S30 valve with a corny post as I do now.

 

[Jasper]

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 know this is an old thread but I’m amazed at the amount of people who can’t get a seal on the cap, I’ve got 3 of these kegs and never had a problem. As some have suggested check the barrel neck top surface to make sure there is no mould flashing that will cause a problem. A round section “o” ring smeared all around with Vaseline is all that is needed and hand tight with maybe a nip up with a cap tool or similar. Putting ptfe tape or anything else around the thread serves no purpose, as the thread is there as a means to tighten the cap and has nothing to do with making a seal, the “o” ring alone performs this quite adequately. The rubbers on the valve need changing occasionally but can easily be checked with soapy water. Pressure test with CO2 and with barrel empty, if you test with water or any liquid CO2 will be absorbed into the liquid and give the impression that the barre is leaking.

 

[Perrin_Abara]

@Buffers brewery is the subject matter expert. Sorted me out a treat.

 

[Buffers brewery]

Hi @Jasper . I think the original post was regarding an ill-fitting cap where the thread "jumped" and couldn't be tightened properly. Other PB users have posted the same problem