# Degassing Pub Kegs



## ads7 (12/10/05)

Hi guys

quick question. why do kegs need to be de gassed if they r going to be stored in a coolroom if not completly empty. A mate and me were chewing the fat pondering this. Any ideas?


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## Batz (12/10/05)

Just because :blink: :huh:


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## Darren (12/10/05)

Maybe they become over-carbonated?


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## ads7 (12/10/05)

would that make it taste metallic? I am talking about in a pub- probably shoyldve mentioned that?


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## Hoops (13/10/05)

ads7

Darren is correct. You de-gas kegs if you are running an unbalanced system where pouring pressure is higher than carbonation pressure.
Leaving them at pouring pressure would overcarbonate them so to combat that you de-gas them at the end of the night.

I have no idea where you get the impression that it will make the beer taste metallic though? :huh: You're only getting rid of a little CO2.

Hoops


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## ads7 (13/10/05)

Thanks.


My mate who tasted it said it tasted metalic? 

Ads


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## Jez (13/10/05)

sorry - I keep thinking of "clouds taste metallic"

great album.


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## jayse (13/10/05)

ads7 said:


> why do kegs need to be de gassed if they r going to be stored in a coolroom if not completly empty.
> [post="82375"][/post]​






Hoops said:


> Leaving them at pouring pressure would overcarbonate them so to combat that you de-gas them at the end of the night.
> 
> [post="82434"][/post]​



I think the pressure for serving beer through big chilling systems would have to be up around 5x that of the carbonation of the beer, somewhere around 40psi. As is the beer would be under that for a long time and ussually cold. The way all the places I have scene is they use a mix of nitrogen and only enough Co2 for all for the beer to stay at the right carbonation but at much higher pressure. This still looks to me like everybeer in the end would have the same carbonation, unless you used a even higher ratio of Nitrogen to C02 for beers with less carbonation.
If this is this method they use then the theory goes you shouldn't have to degas the keg because theres only 10psi or so of C02 the other 30 psi is nitrogen which won't affect the beers carbonation, there in leaving the beer with around 2.5 volumes Co2 at 2c.
If it were only C02 your using then i'd say it would be difficult unless the kegs were around 30c  You'd have to degas them every night but they'd still be over carbonated after a day at 40psi I'd imagine. A full keg at 40psi i guess would be fine but once you get a few pints of head space or you let me loose on the keg it would became a problem. Iam pretty sure the N2-Co2 mix saves all these problems.

The metallic taste could be carbonic acid because the beers have been force carbonated to within a inch of there lives.

Ramble on
Jayse


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