King keg leak

[Petefin]

Hi Guys,

I'm new to the forum and just getting back into brewing after many years away.
Got myself a bottom tap King keg. As an engineer and years ago having all sorts of leak problems with a Rotokeg, I thought I would address potential problems before starting my first brew.
I have fitted a car type valve and a 0 to 30 psi pressure gauge to the cap.
I have half filled it with water then slowly pressurised the keg, applying soapy bubbles around everywhere looking for leaks.
All my mods are good at 15 psi, but the pressure release valve is leaking after 2 psi!
I have carefully eased back the rubber ring and applied some petroleum jelly but it is still leaking.

As an engineer, the rubber band method of pressure control is a joke. I am tempted to block the hole and fit a separate spring operated pressure relief valve that operates between 10 and 15 psi.
This in my mind, please correct me if I'm wrong, would be a proper fix, but I'm not so confident of finding a suitable pressure relief valve.

Any advice would be greatly appreciated.

Cheers, Pete

 

[Petefin]

Hi again,

Just found a UK valve manufacturer who does a range of pressure relief valves in 5 psi increments from 5 psi upwards.
What would be the recommended working pressure for a King keg?
Would it sit all day at 15 psi or would I be safer with the 10 psi valve?

Cheers, Pete

 

[terrym]

I suggest you should aim to replicate the RV set pressure as was supplied, or as stamped on the PB, and certainly no more, although less is fine. If you are unsure contact the manufacturer. And I suggest you operate your PB at a pressure less than the RV lifting pressure.
Modifying stuff on PBs is not to be taken lightly unless you absolutely know what you are doing and understand how you are affecting the pressure containing integrity of the PB and falls into a category of 'Safe Brewing'.
https://www.thehomebrewforum.co.uk/threads/safe-brewing.82795/

 

[kelper]

Considering its simplicity, I think the rubber band makes a good relief valve. Are you 100% certain the leak is from the rubber band and not lower?

 

[Sandimas]

Got myself a bottom tap King keg.

New or secondhand?

Because the rubber band on the pressure relief valve has a shelf life and will start leaking at low pressures after a while as it loosens/ages, they need replacing every few years. Should be an easy fix, homebrew shops or online will stock replacements.

 

[Petefin]

Hi Guys,

Thanks for the replies.
The King keg is new. It's disappointing that the rubber valve is leaking at 2 psi. As increase the pressure up to 10 psi, it only gets much worse.
As I mentioned before, I am an engineer, been involved with pneumatics for decades. A rubber band is about as crude as you can get when it comes to pressure regulation. Especially if corrosion occurs on the brass face, rubber can perish or become brittle, it is a truly poor way to do it. But in its defence, its simple and cheap.
The Kingkeg has no pressure markings, a bit naughty for a "pressure vessel"!
But it appears, from other posts on the forum, that they are safe up to 15 psi, so I think I will go with a 10 psi relief valve, which I can check the accuracy of at work along with the readings on my guage.

Cheers, Pete

 

[kelper]

You could fill with water and hydrotest at 15psi.

 

[terrym]

Hi Guys,

Thanks for the replies.
The King keg is new. It's disappointing that the rubber valve is leaking at 2 psi. As increase the pressure up to 10 psi, it only gets much worse.
As I mentioned before, I am an engineer, been involved with pneumatics for decades. A rubber band is about as crude as you can get when it comes to pressure regulation. Especially if corrosion occurs on the brass face, rubber can perish or become brittle, it is a truly poor way to do it. But in its defence, its simple and cheap.
The Kingkeg has no pressure markings, a bit naughty for a "pressure vessel"!
But it appears, from other posts on the forum, that they are safe up to 15 psi, so I think I will go with a 10 psi relief valve, which I can check the accuracy of at work along with the readings on my guage.

Cheers, Pete

1. If its any help the budget PBs are stamped 'Max Working Pressure 15psi', and you are 100% correct about the King Keg not being similarly stamped, given its supposed to be a quality product.
2. And I find it refreshing to find someone else who appears to understand the importance of what these things actually are and doesn't adopt a gung-ho approach to operating and modifying them when they have no real idea of what they are dealing with.

 

[Petefin]

Thank you for your kind words Terym, once I have the mods finished to my King keg cap, I'll post some photos.

Cheers, Pete

 

[Petefin]

Hi Guys,

Here are a few photos om my King keg modifications.

I machined up a stainless steel bar to take the gauge and 10psi relief valve. I also machined an O ring groove to ensure a gas tight seal.
The original brass relief valve had a 3mm hole connecting the inside of the cap to the rubber band. I blocked this off with a 3mm drill blank and some Locktight bearing lock solution. You can see the blanked off hole in the photo of the underside of the cap.
I also fitted a car type valve for pressure testing.

I didn't like the finish on the keg lip where it seals against the cap O ring, so I got a flat piece of steel (a surface block, very flat!) with a sheet of fine emery paper on it and lapped the lip until perfectly flat.

I than filled the keg so that the bottom tap was submerged in water and pressurised the keg with air until the valve released the excess pressure, stopping just under 10psi.
I left it for 24 hours and there was no movement on the gauge. RESULT!

The relief valve was purchased from Context Pneumatics in Bolton for £13.99 via EBay and the gauge I had lying around.

 

[Rodcx500z]

That's a proper job, happy brewing

 

[BridgeBrew]

Great job. Moded all my Kegs, and had no problems at all. The poppet relief valve is a great idea. the old beer spheres used to come fitted with a proper blow off valve, not the cheapo rubber band system.

 

[Petefin]

Hi Guys,
Nearly finished my first barrel of beer, held its pressure no problem.
Just bought my second King Keg & about to do the same mods as the first. Don't like the waiting time associated with only having one barrel

Cheers, Pete

 

[user 18729]

That’s a cracking modification, really impressive. At 15psi you can happily force carbonate your beers as well

 

[Hazelwood Brewery]

Hi Guys,

I'm new to the forum and just getting back into brewing after many years away.
Got myself a bottom tap King keg. As an engineer and years ago having all sorts of leak problems with a Rotokeg, I thought I would address potential problems before starting my first brew.
I have fitted a car type valve and a 0 to 30 psi pressure gauge to the cap.
I have half filled it with water then slowly pressurised the keg, applying soapy bubbles around everywhere looking for leaks.
All my mods are good at 15 psi, but the pressure release valve is leaking after 2 psi!
I have carefully eased back the rubber ring and applied some petroleum jelly but it is still leaking.

As an engineer, the rubber band method of pressure control is a joke. I am tempted to block the hole and fit a separate spring operated pressure relief valve that operates between 10 and 15 psi.
This in my mind, please correct me if I'm wrong, would be a proper fix, but I'm not so confident of finding a suitable pressure relief valve.

Any advice would be greatly appreciated.

Cheers, Pete

I see from the thread you’ve sorted out a solution but these valves are renowned for leaking, the rubber band loses elasticity and needs replacement - even when new, it may have been on a shelf for months.

 

[Hazelwood Brewery]

Hi Guys,

Here are a few photos om my King keg modifications.

I machined up a stainless steel bar to take the gauge and 10psi relief valve. I also machined an O ring groove to ensure a gas tight seal.
The original brass relief valve had a 3mm hole connecting the inside of the cap to the rubber band. I blocked this off with a 3mm drill blank and some Locktight bearing lock solution. You can see the blanked off hole in the photo of the underside of the cap.
I also fitted a car type valve for pressure testing.

I didn't like the finish on the keg lip where it seals against the cap O ring, so I got a flat piece of steel (a surface block, very flat!) with a sheet of fine emery paper on it and lapped the lip until perfectly flat.

I than filled the keg so that the bottom tap was submerged in water and pressurised the keg with air until the valve released the excess pressure, stopping just under 10psi.
I left it for 24 hours and there was no movement on the gauge. RESULT!

The relief valve was purchased from Context Pneumatics in Bolton for £13.99 via EBay and the gauge I had lying around.

View attachment 22209
View attachment 22210
View attachment 22211
View attachment 22212

I assume you’re not pressurising through the S30 valve? If you are you need a cable tie round the rubber seal or at some point you will blow this off - into your beer and letting all the gas out.

See below...

 

[Petefin]

It shouldn't be a problem as long as you let the gas go from the co2 cylinder into the barrel slowly. It's the pressure in the barrel that pushes against the rubber giving a seal. The big problem was the pressure relief rubber band, a veritable crap design done away with by fitting a professional relief valve. At just £13 for a 15 psi 1/8bsp valve, well worth the money. But I do appreciate that not everyone has the facility to machine up a fitting to take a gauge and a relief valve with an "O" ring seal to fit to a barrel lid. Business opportunity ?

Cheers, Pete

 

[Buffers brewery]

I’ve approached the problem you’re experiencing in two ways @Petefin. First I replaced the rubber band with a radiator bleed valve on the basis that the pressure only rises during carbonation and provided you keep an eye on it any excess pressure could be bled off.

Then I moded the HB valve to make it a right angle and got rid of the rubber band completely and replaced the bleed valve with a proper 15 psi safety valve.

I’ve since replaced the elbow with just a piece of copper tube to get rid of the large dead space in the elbow.

Given the choice I’d opt for the radiator valve with regular checking but the purists amongst us would disapprove and opt for a proper safety valve. Hope that helps.

 

[Petefin]

I like your T with the pressure relief valve and the tee, much easier and no special machining required,, good job!

Pete

 

[Buffers brewery]

I like your T with the pressure relief valve and the tee, much easier and no special machining required,, good job!

Pete

Thanks Pete. If you use a safety valve remember to block off the safety valve port in the HB valve. I posted a YouTube video that might help.

oops, sorry Pete, just read your thread again and saw you got it covered. BTW I used a redundant glass shelf from my brew fridge as a surface plate with a sheet of W&D to smooth the neck face of my KK.