improving kegging for home serving

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hoppyscotty

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Had a discussion at the local home-brew club meet up with a 'meet the brewer' event. The discussion was around kegs and maintaining the quality of beer as you consume the beer and create more headspace in the keg. IT was observed that generally as you empty the keg assuming it takes a few weeks to get through it, the bottom quarter or so of the beer generally has less hop flavour and aroma, the hypothesis being you lose alot of the aroma in the headspace....opening up an empty keg for washing you're always greeted with a lovely wiff of hops...thats all flavour and aroma that should be in your beer.

It was discussed that the plastic Key Kegs are a great solution to this as the beer is contained within a bag so as you consume the beer the bag volume reduces maintaining carbonation and preventing any headspace in forming. The problem with key kegs are they are not reusable (unless anyone knows of any hacks) so a very expensive option for the home brewer.

I was thinking about how I could modify a corny keg to mimic how a key keg works using a polypin bag. Beauty is you don't need to use CO2 for serving and can just use compressed air as its not required to maintain carbonation and doesn't come into contact with the beer.

The polypin bags have a tap on them and a specific 'vitop'attachment to enable it to be filled. I was thinking about:-
1. drilling a hole in a corny keg lid so the polypin bag tap can be attached through the hole and remain external to the keg.
2. Attach the vitop connector.
3. Since I will be filling with ready carbonated beer I can't just fill the bag as it will immediately inflate as I fill it and the beer will foam up, so will pressurise the keg with compressed air to just a couple of PSI more than carbonation pressure via the corny keg gas post.
4. Fill the bag with carbonated beer by reducing pressure of keg air with spunding valve on the corny keg gas post.
5. Once filled connect the Vitop connector to the kegarator beer tap
6. Increase compressed air pressure to the corny keg gas post. You can have a much higher pressure here than the carbonation pressure which aids serving.

What do you reckon? Chances of success? Biggest challenge I can think of is sealing the keg around the protruding polypin tap hole.
 

hoppyscotty

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Well its about 3 down on my current 'projects to do list' so might be a while before I start messing about on this, Just in the process of pondering if its got half a chance of working.
 
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…… Biggest challenge I can think of is sealing the keg around the protruding polypin tap hole.
I’ve seen ruptured diesel fuel lines made completely “drip free” under pressure with this stuff:


Enjoy!
:hat:
 

hoppyscotty

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I'll look into that sealant thanks. The message is that you can pressurise outside of the bag as high as you like as it doesn't affect carbonation...the carbonation of the beer wont change from what it was when you fill the bag.

The other idea is to have the polypin bag tap and vitop connector inside the keg and connect to the existing corny keg liquid post thus avoiding the need to drill through the keg lid. Just seems like a bulky setup to have inside the keg and might risk puncturing the bag when the bag is full.
 

Centiweasel

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Seems complicated, You could use a lid with a gas post on it, attach a deflated bag to that, then do a pressurised transfer the normal way using the spunding valve on the regular gas post, then fill the bag with compressed air to serve, the bag would take up the head space.
 

hoppyscotty

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you're probably right that there is a simpler way...I'm using the key keg design as a reference and trying to mimic that, but your suggested way would achieve the same end except the issue you would have would be to stop the beer being separated into to chambers if the bag seals in the middle of the keg as it inflates...how would you control the bag and keep it either at the top of the keg or bottom so all the beer stayed together unless you physically attached the bag to the inside of the keg...a bit like a pressure vessel in an unvented central heating system where it uses a diaphragm attached to the inside of the vessel. maybe the addition of a few tubes linking the bottom of the keg to the bottom to allow beer to pass by as the bag inflated. I have a keg lid with a ball lock post on it for a carb stone that could be very easily re-purpsed to fill the bag.
 
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