Leaking barrel cap

[Steeley]

Need a bit of advice, I have a couple of KK barrels, one of them is causing me issues, first time I used it, it was perfect, 2nd time I had an issue with to much head, but I got good advice from one of the guys on here and it was sorted, now I brewed the third time with the barrel,no pressure, I put a new cap seal in, I put PTFE tape around the threads, and tightened it up with my hand, then used a spanner to turn the cap an extra quarter of a turn, now any ideas.

 

[kelper]

I suggest to grease the seal with vaseline or food-grade grease. It only needs to be hand tight. I have fitted Schrader valves to mine so I can pressurise them and test for leaks using a car tyre pump. I don't ever find a problem. Fill with water and then pressurise and turn the barrel on its side to see if there are any leaks. There is no point using thread tape as that is not where the seal takes place. It is a bodge. If it leaks past the rubber seal in the cap that needs to be fixed. Some people replace the original o-ring with a square-section seal but I've tried both and there is no difference.
Terrym will post soon to disparage all pressure barrels but there are many happy users on this forum

 

[terrym]

There is no point using thread tape as that is not where the seal takes place. It is a bodge. If it leaks past the rubber seal in the cap that needs to be fixed. Some people replace the original o-ring with a square-section seal but I've tried both and there is no difference.
Terrym will post soon to disparage all pressure barrels but there are many happy users on this forum

Ah. Not this time.
But what I will say is you are 100% right about tape on the cap threads being a bodge to fix a leaking cap seal.

 

[kelper]

As an engineer at sea, I dispaired when my lads put thread tape on the threads of a compression fitting! Thank you good-natured response to my teasing.

 

[Steeley]

I suggest to grease the seal with vaseline or food-grade grease. It only needs to be hand tight. I have fitted Schrader valves to mine so I can pressurise them and test for leaks using a car tyre pump. I don't ever find a problem. Fill with water and then pressurise and turn the barrel on its side to see if there are any leaks. There is no point using thread tape as that is not where the seal takes place. It is a bodge. If it leaks past the rubber seal in the cap that needs to be fixed. Some people replace the original o-ring with a square-section seal but I've tried both and there is no difference.
Terrym will post soon to disparage all pressure barrels but there are many happy users on this forum

Thank you for that I will try, but what you have said I might be over tighting the cap, I was told to really tighten it, but I will try what you have said, thanks

 

[Steeley]

As an engineer at sea, I dispaired when my lads put thread tape on the threads of a compression fitting! Thank you good-natured response to my teasing.

So what about the tightness of the cap, just to nip it or really make sure it’s really tight

 

[Gerryjo]

So what about the tightness of the cap, just to nip it or really make sure it’s really tight

Just sweeten the cap so as it presses on the seal. When you over tighten it's deforms the seal as it's being squeezed too hard therefore causing it to leak.

 

[Steeley]

Just sweeten the cap so as it presses on the seal. When you over tighten it's deforms the seal as it's being squeezed too hard therefore causing it to leak.

Thanks for that, I will remove the cap, put a smear of Vaseline on the cap threads, put no PTFE tape on and just nip the cap tight.

 

[kelper]

Remove the seal and smear it with vaseline