Better quality King keg cap

[Buffers brewery]

So, looking for something to do, I’ve given this thread a bit of thought @Petefin . You say when you tighten your cap the thread jumps suggesting a very loose fit on the barrel. My theory is that if the cap is significantly off-centre to the barrel that would cause different loading on the seal from one side to the other resulting in a leak. So how brave are you feeling @Petefin ?
I’ve done a little trial on 2 fronts.
The first thing I did was to modify (butcher) a cap and cut the threaded section to produce castellations.

Then fitted to the barrel and using a jubilee clip gave it a squeeze to reduce the float...and it did and I could still tighten and loosen the cap!

Decided to give it a go. Fitted bits and pumped it up....

Sadly had a leak
So the second front.
I inspected the seal seat surface inside the cap with a whittled lolly stick and could detect little wrinkles so wrapped a thin slither of W&D over the end of the lolly stick and gave it a rub to get a nice even surface.
Second try proved successful.
Try it if you dare. No guarantees

 

[Buffers brewery]

As a post script to my previous post, I investigated the geometry of the cap to keg junction. I removed the seal from the cap and filled (almost) the cap seal groove with vaseline and screwed the cap onto the barrel as tight as it would go. When I unscrewed and inspected it the vaseline had not been squidged out! When I measured the diameters the outside diameter of the keg was bigger than the cap at the end of the crew thread which stops 3-4 mm from the seal face. So that could mean that when you think you’ve tightened the cap down onto the seal you have in fact bottomed out on the barrel neck. I sanded a chamfer on the outside of the barrel neck so that I could screw the cap fully home so the 2 sealing faces touched (and the vaseline was squidged out).
Going to have a lie down now

I’d recommend doing this check/mod first

 

[Petefin]

Hi Buffers Brewery,
That makes perfect sense and would explain why the square O ring is no better Than the round section one. I will investigate that, thanks

Cheers, Pete

 

[Clint]

That's the impression I get regarding my replacement lid...didn't seem to be bedding down properly..I'm gonna gravity dispense the last couple of pints tomorrow night,give it a scrub and have a play.
I wouldn't mind fitting a pressure guage of some description to monitor it..

 

[Petefin]

I also like your mod with the jubilee clip. I will cut slots in the lugs to feed the band round, that way it can't slip off and my spanner will still fit.

Cheers, Pete

 

[Buffers brewery]

I also like your mod with the jubilee clip. I will cut slots in the lugs to feed the band round, that way it can't slip off and my spanner will still fit.

Cheers, Pete

I just filed a flat on a couple (opposites) to stop the clip slipping off. Can still get the spanner on the top part.

If you cut a slot in all the lugs you might not get enough purchase to do the cap up tight. Just a thought.

 

[Petefin]

Good point!

 

[Hazelwood Brewery]

I’ve been using King Kegs for years and have 8 on the go at any given time, from this weekend my flock will increase by 1 more. My advice, use the original cap seal, the round section fills a bigger gap than a skinny flat one and is more compressible. You do need to give it a bit of grunt with a cap spanner. I’ve never had a cap jump threads though so it sounds like you may have a Friday job there (or maybe just lost your rag! ).

Second, @kelper makes a good point about over-tightening. In the early days I did this a lot. The rubber seal for the S30 valve should be pinched but not squeezing out where it’s been wrenched. Hand tight and a little bit more with a spanner.

The most likely culprit is the pressure release rubber. These can be a pain in the backside and leak even when they seem to be working ok - the rubber loses elasticity so doesn’t seal properly.

 

[kelper]

My King Kegs came with orange caps. Your cap looks like the two I bought from Ballihoo!

If you sand your cap it has to be flat, but it also has to be at exactly 90 degrees to the axis of the barrel. In most engineering situations, pressure helps to push the o-ring into a tight seal. I think looking for MINOR imperfections in the top of the barrel is a red herring. I would carefully measure the ID and OD of the existing o-ring (in millimetres) and order a replacement from eBay. I would try silicone rubber, NBR and Viton.

 

[Petefin]

Hi Hazelwood Brewery,

Have a look at my earlier posts, the pressure release rubber is long gone, it's such a poor system, I got shot of it right away!
Experimenting with different O ring material now. The standard O ring and the replacement square section O rings are too hard in my humble opinion. As for size, I am restricted to the groves in the cap the O ring sits in.

Cheers, Pete

 

[foxy]

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

I'm in Australia, they are dirt cheap here $7 and $9, 20 and 25 litre respectively. Each has 3 litres head space. I now also use air from a picnic pump, can't see the point in wasting money on co2 when air is free!

 

[Buffers brewery]

I now also use air from a picnic pump, can't see the point in wasting money on co2 when air is free!

I thought the idea of using CO2 was to keep oxygen away from your brew. Am I misunderstanding your post?

 

[foxy]

I thought the idea of using CO2 was to keep oxygen away from your brew. Am I misunderstanding your post?

Yes, think outside the square, think Archimedes. How can you use air and keep oxygen away from the beer.

 

[Richie_asg1]

That's clever - and cheap, and great for parties.
You do realise you have just invented "The Sub" torpedo?

If the caps are still giving problems, you may want to add another sealing disc that has an O ring on the outside diameter, and is a wedge fit in the neck of the PB. Similar to a cork.

Either that or two plates with a low modulus silicone seal in the middle and some form of cam action clamp (or bolts) to pull the two together - identical in operation to those wine savers with a lever on the side.
This should have the effect of pushing out the inside of the neck into the threads of the cap more.

There is always the 3D printing option, or if you are brave turning one up on a lathe, (coarse threads up to a face is always tricky).

I suppose you could avoid the problem completely and fit your own style of cap in a new adaptor, and just plastic weld the two together....or buy a corny keg.

 

[Buffers brewery]

Yes, think outside the square, think Archimedes. How can you use air and keep oxygen away from the beer.

So, trying to remember my “O” level physics from 1965! Archimedes was about displacement of fluids to measure density? Are you saying the CO2 produced during carbonation displaces the air you add and shields the beer from the oxygen in the air?

 

[Hazelwood Brewery]

Yes, think outside the square, think Archimedes. How can you use air and keep oxygen away from the beer.

Some kind of bladder or hydraulics?

 

[Buffers brewery]

Have you fixed it @Petefin

 

[foxy]

Some kind of bladder or hydraulics?

Correct, I have been trying it in a keg with a plastic bag and water and it works. Going to a party with wall to wall pish artists is fine, just pump air straight into the beer. Can't do that bringing home half a keg, unless you took along a gas cylinder. So saves a lot of unnecessary carting, and beer.

 

[Petefin]

Hi Buffers Brewery,

Got the new square section O ring cut today using a softer silicone.
Should get it tested tomorrow.
I like the idea of cutting slots in the lid to tighten the threads. But rather than cutting the lugs the spanner fits onto, I will drill a small hole in each of the lugs and thread stainless locking wire round the cap. With this, the lugs will retain their strength and the locking wire can be drawn up to tighten the threads.
But I'll try the new washer first.

Cheers, Pete

 

[Buffers brewery]

Correct, I have been trying it in a keg with a plastic bag and water and it works. Going to a party with wall to wall pish artists is fine, just pump air straight into the beer. Can't do that bringing home half a keg, unless you took along a gas cylinder. So saves a lot of unnecessary carting, and beer.

When I went on a brew day course, the brewer mentioned that some breweries supply their beer in special plastic bags inside the barrel and the space between the barrel and plastic bag was pressurised to dispense the beer. Is that what you’re doing?