Beer always flat from a keg

[match]

I've always bottled my beer, but recently acquired a plastic pressure barrel (an old wide-mouthed one with a pressure gauge retro-fitted to the lid) and decided to try out kegging to save myself some effort.

However I can seem to serve anything other than a flat pint.

I added the finished beer to the keg along with 90g of priming sugar, which I then left for 2 weeks. During this time the pressure gauge gradually increased until it stopped around 11-12 PSI (barrel is rated to 15) - so I assumed it had finished priming. The keg has been sat at cool room temps (16C) the whole time.

I briefly tried serving at this point, but the beer (obviously) came out as a ton of foam. I used the pressure-release valve on the lid to lower the pressure, a few PSI at a time, until the beer poured reasonably safely (around 4PSI) - however despite having a nice foamy head, the beer itself is completely flat.

Have I missed something obvious here? What do I need to do to get that gas into the beer? I have an S30 cylinder/valve so I can repressurise if needed.

[Jim]

What you need to get the gas into the beer is time. Top up the gas to 10 psi or so, then leave it for a few weeks (with Xmas coming that might not be practical, but see below).

The cooler the beer is the better as well - if you can get it to 8 or 10C (or even less, but watch out for the barrel seals going hard and leaking), that will be better and the gas will dissolve quicker.

[Robwalkeragain]

Probably a bit warm to absorb the gas properly too. Once it's built up pressure keeping it cool will help absorb it into the beer. So er, what Jim just said. Doesn't sound like there's leaks or owt and you're not doing much wrong.
You're only likely to get "real ale" carbonation mind, so if you're after lager fizzy, I'd look at another method.

[match]

Thanks for the advice - went back to repressurise it and it had jumped back up from 2 to 8, presumably gas coming out of the beer, so have added co2 back up to 11 and will leave it for a couple of weeks more (fortunately I have other beer for Christmas!)

Will see where's the coldest place in the house, but will avoid outside due to risk of the neighbours drinking it all... I mean the risk of frost! :-p

[Kingfisher4]

I had been dissuaded from trying the king keg I bought, due to an initial disaster with the carbon dioxide cylinder which failed at the valve (despite dipping in boiling water et cetera)

I might experiment again, particularly as I like low carbonation in my bitters. Especially as last summer was a nightmare stopping my bottled beers becoming over carbonated, even with little or no priming sugar and good final gravity.

[BarnsleyBrewer]

I always force carbonate by introducing co2 or 70/30 gas mix and then releasing the pressure, I do this a couple of times to purge out any o2...
I then introduce co2 whilst vigorously shaking the keg so the brew absorbs it quicker, I then leave it for a week or so under pressure then drop to around 6psi to serve.
Dunno if the same applies to King Kegs because I use Cornies??

BB