Spunding

[SlanginDueces]

Just ordered a spunding valve for my next brew (Helles) and wanted to see what everyone does for their process. I can pressurize my fermenter so I am thinking about trying it out to naturally carbonate.

 

[SlanginDueces]

I guess not too many people are spunding....

 

[hopjuice_71]

I'm surprised you have no responses. I believe a lot of people so this now and in a variety of different ways using simple to more complex processes. I'll give you mine, which is relevant to fermenting in corny kegs but it would also be applicable to any fermenter you can pressurize. Once I have pitched my yeast I'll do one of two things: either attach the spunding valve to the gas out right away and dial in a low pressure or attach a blow-off tube to the gas out. After an accident with a vigorous fermentation, overfilled keg, and a spunding valve fouled with yeast, I tend to go with the blow-off tube now. Either way, I let the fermentation ride with essentially little pressure. After a period of time I then pop on the spunding valve and dial in my desired pressure, which is based on the present temperature of the fermentation and my desired final CO2 level. When to increase the pressure on the spunding valve is an interesting consideration. I have heard of many people doing it quite scientifically - forced ferments, gravity measurements, etc - to determine when there are enough gravity points left to give the desired carbonation. My day job is as an overly detail oriented scientist so I tend to avoid bringing this home to my hobby. I make the judgement of when to spund by a combination of how much the fermentation is still bubbling from the blow off tube and gut feeling. Usually I am dialing up the pressure around day 5 or 6, plus or minus a day depending on the OG of the beer and how vigorous the fermentation was. This approach hasn't failed me yet. At any rate, its pretty forgiving because you can dial in the pressure on the spunding valve making it hard to over carbonate, but it does require a little vigilance, unless you have worked really hard to calibrate your spunding valve. Once I'm happy the fermentation is complete I can cold crash the already carbonated beer and jump it to a serving keg. If I have spunded too late and my beer is a little undercabonated (only happened once) its easy to top off the pressure in the serving keg with CO2.

I hope this helps. I would also be interested to hear what other processes people are using.

Cheers

 

[SlanginDueces]

Thanks for the response. What pressure do you set your valve to when you start allowing the fermentation to carbonate the beer and have you seen any effect of the yeast finishing up under increased pressure?

 

[hopjuice_71]

I use the carbonation tool in BeerSmith. For example, if I end with my fermentation at 68 F and I am aiming for 2.2 vols of CO2 I'll dial the pressure in at 23 psi. To do this I fully close the spunding valve, leave it until it hits 24 psi, open the valve until I hear a slight hiss, then monitor it a few times a day to tune the valve so that it stays stable at 24.

I haven't had any issues with yeast properly attenuating this way but I am not really fermenting under pressure. The vast majority of the fermentation is done in the first 5 or so days when I have the blow-off tube on and I am just capturing the CO2 from the remaining little bit of fermentation. Some do their entire fermentation under pressure but I believe this is typically only around 6-10 psi.

 

[flugelizor]

Thanks for the Beersmith tip!
I have been looking for a carbonation chart, but they all stop at 65F.
But my conditioning temperature normally is in the 70s.

 

[Sbe2]

FWIW I have been kegging with ~6 pts left w/o a spunding valve. I haven’t over carbed yet