pressure regulators behaviour, sugar carbonating

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Nov 4, 2018
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First time making cider - I have this standard pressure regulator like most other folks (not this really, but strikingly similar)


I've set it to 2.3 bar (35 PSI) and let it sit for some 3 weeks, hoping my 17 C (59 F) cider barrel would carbonate. Result: apart from some nice looking foam (when poured), there is no sparkle felt in the mouth. So today I have undertaken the other carbonation route: sugar priming. Used a calculator for the cider volume, CO2 volume and temperature. Started pouring sugar into the cider aaaand... problems:

1. It turned into a geyser spouting cider all over the place.... Is this normal ? Used white table sugar.

After cleaning the mess I have poured the rest of the sugar one table spoon at a time, waiting for it to settle in between the spoons. Then sealed it, pushed out the air and allowed some 1.9 bar (28 PSI) from the CO2 cylinder. I have set the pressure regulator for that value. Big question:

2. Am I guaranteed not to exceed the 1.9 bar pressure on the regulator no matter what the priming sugar + cider does inside the keg ?

Many thanks
1) Your cider foams when granular sugar is added because the sugar granules create nucleation sites for the CO2 to come out of solution. With lots of nucleation sites, lots of foam is created. The foaming is evidence that your cider is carbonated to some level.

2) No. If you have a check valve between your cider vessel and the regulator (often integrated into the red handled shut off valve) then the pressure in the vessel can exceed the regulator setting.

I suspect your cider is carbonated just fine. It's just that serving it at such a warm temp knocks most of the carbonation out of solution, so it seems flat in the glass. I suggest you cool the cider by about 20°F (down to ~39°F) for serving.

Brew on :mug:
Oh my.... ok, I have got more questions. I am a bit worried.

I have filled a 2 liter bottle brimful a couple of days ago and put it to the fridge at 36F. Still no fizz to the taste bud.

And to the worry: The cider + sugar is sitting in a commercial 50 liters (13.2 gallons) keg. I do not know the pressure rating for these, but mine are second hand bought, so... The regulator's check valve bursts open at 3 bar (45 PSI, tested). The regulator is also bought SH, you can't find many new brewing accessories where I live.

So everything is SH and the 3 bar / 45 PSI I am worried that it may be too much for my setup. What pressures should I expect to build up inside the keg during this re-fermentation, at 17 C / 59 F and how do I best handle it ? There are 40 - 43 liters of cider inside of it.

Thanks again!
Exactly how much sugar did you add (weight value is best)? Need this to determine how much CO2 will be created in the keg.

The valve on the side of the regulator body is a pressure relief valve, not a check valve. A check valve is a one way valve that prevents back flow of beer or CO2 from the keg into your regulator. For example, if I turn the pressure down on my regulator, it doesn't reduce the pressure in the keg because the CO2 from the keg can't flow back to the regulator. I have to pull the PRV on the keg to relieve the pressure. So, the PRV on the regulator will not prevent pressure build up above 3 bar in the keg, if you have a check valve between your keg and regulator. Again: check valves are often co-located with the shut off valve between the keg and regulator.

The bottle in the fridge may not carbonate at all because of the low temp. To naturally carbonate requires holding the cider at temps where the yeast are active.

Brew on :mug:
Around 300g / 10.5oz of sugar.

Ok, sorry, it was the relief valve that I meant to say. There is no check valve in my setup. So, the PRV on the regulator should prevent pressure build up above 3 bar in the keg if I am reading this right.

As for the bottle in the fridge, it was from the same keg that had been kept for 3 weeks at 2.3 bar. It foamed nicely in a beer-like fashion when it had been filled, but no sparkles when drinking it. Throwing the bottle in the fridge did not help either.