Room temp keg - carbonation issues

[stronk]

I've got quite a specific question which applies to trying to serve from a room temperature keg through a chilling machine. Common practice in UK for events, small restaurants and (less so) people with very small flats in London.

Getting carbonation right for a room temperature keg is an interesting problem, because 'room temperature' changes with the seasons and times of day, while all the common practice online assumes you have kegs in a fridge at a constant temperature. The result: over time the beer equalises carbonation at the lowest temperature the beer reaches, and when the temperature increases the pressure in the keg rises above the regulator's set pressure (carbonation of course remaining constant, which is why the pressure rises as temp rises in a sealed system). When you serve when the keg is above its minimum temperature, the regulator won't give more CO2 until the pressure reaches a value lower than the level required to hold the CO2 in the beer, which means foaming is an ever-present issue (these machines are notorious for it). You can turn up the pressure to counteract this, but then you end up creeping up over time until the beer is overcarbonated.

I'm looking to solve this by careful manual control, but can't find the regulator type that I need and am wondering if it even exists. Maybe someone on the forum knows? I need a regulator that shows the set pressure separately from the current pressure. All the beer type regulators I have seen elide these two, showing only the current pressure (which will always be the set pressure in normal circumstances, but not in mine). Maybe this calls for a digital regulator (do these exist/are they affordable for homebrewers)?

The theory is if I can know accurately a) the current pressure in the keg and b) the pressure the regulator is current set to maintain, then I can compare the two and adjust the regulator to maintain the current keg pressure while serving, then turn off the gas supply when not in use, so I don't end up with that new higher pressure over-carbonating the beer when it cools down at night.

Many thanks for any insights!

 

[bracconiere]

is there a way you can use a soda fountain? just leave the beer flat and carb on the fly?

 

[Bubbles2]

Insulating your Keg so the temp swing is not so drastic, perhaps only a degree or two.. An insulation jacket if very limited space?

 

[ba-brewer]

You could add a second pressure gauge down stream of the check valve close to the keg disconnect.

 

[stronk]

Thanks for the suggestions. Soda fountain is interesting, hadn't considered that. Not sure if it would maybe lead to too much foaming in beer, since even sodas foam a lot through the fountains and they don't have head-forming proteins.

The other two suggestions also interesting. The problem isn't so bad for kegs in my flat where I can keep the keg in a cupboard and temp change is not so bad. Much worse for kegs kept in a friend's garage (I did advise him to get a kegerator rather than a chilling tap, but I think he liked the idea of the higher tech option).

Second pressure gauge would work, I think, even if not as elegant as having an all-in-one regulator. I'd need to have (apologies for rough sketch, hopefully will format correctly):

keg---shut-off valve---regulator
___^___
gauge#2

Close shut off valve after each pouring session. Before next pouring, check gauge#2 and if needed adjust regulator to match before opening shut off valve. When done, close shut-off valve. It achieves what I wanted, though my plan is still a hassle (and I'll probably need to invest in some more precise pressure gauges).

Would be nice to automate it, but I don't think that's feasible to do purely mechanically.

Thanks again.

 

[K_tile]

Could you set pressure and use flow controlled taps to adjust at faucet?

 

[stronk]

I do use flow control taps (which are fantastic, highly recommend) but they don't solve the basic problem which is even a small increase in keg pressure vs regulator target pressure will cause bubbles in the lines when serving, as the pressure in the keg drops below the equalised pressure keeping the carbonation in the beer. Even when flow is very slow, bubbles will cause foaming because they make the flow turbulent at the faucet.

I know insulation helps. Will try the process above when I find time to buy another pressure gauge.