# Water as a spunding valve?

### Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

#### Djangotet

##### Well-Known Member
Hey I am definitely not smart enough to figure this out but I’m wondering if I wanted to ferment under pressure and I put the gas out hose into a gallon of liquid, how much psi would that generate? Is it possible to generate anywhere near 5 psi by altering the water? Would water pressure do enough to give the benefits of pressure fermentation without carbonation? After you could just force carb. I keep hearing that spunding valves are not accurate so I’d almost rather the beer not carbonate to an unpredictable level.

Last edited:

#### TheMadKing

##### Western Yankee Southerner and Brew Science Nerd
HBT Supporter
The volume is irrelevant. It doesn't matter whether you put the hose into a gallon of water or the ocean, the amount of pressure needed to push the bubble out of the end of the tube is determined by the head pressure of water over the tube end (so the depth of the tube)

Last edited:
OP
OP

#### Djangotet

##### Well-Known Member
The volume is irrelevant. It doesn't matter whether you put the hose into a gallon of water or the ocean, the amount of pressure needed to push the bubble out of the end of the tube is determined by the diameter of the tube and the head pressure of water over the tube end (so the depth of the tube)
Interesting, my goal is to retain about 5 psi of pressure in my keg. I will be using the fermentation gasses from my first keg to purge my second one. I don’t wanna lose all the aroma. Probably a spunding valve is my best option?

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
HBT Supporter
The volume is irrelevant. It doesn't matter whether you put the hose into a gallon of water or the ocean, the amount of pressure needed to push the bubble out of the end of the tube is determined by the diameter of the tube and the head pressure of water over the tube end (so the depth of the tube)
Yes, and just for reference, you would need the end of the hose about 11 feet deep in the water to get 5 psi.

Brew on

OP
OP

#### Djangotet

##### Well-Known Member
Yes, and just for reference, you would need the end of the hose about 11 feet deep in the water to get 5 psi.

Brew on
Is the very little amount of pressure applied when submerged in a gallon of water enough to reap the benefits or should I just get a spunding valve with a 10psi limit?

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
HBT Supporter
Is the very little amount of pressure applied when submerged in a gallon of water enough to reap the benefits or should I just get a spunding valve with a 10psi limit?
If you want more than 1 psi, get a spunding valve. You could get 1 psi by connecting to the liquid out post of a keg full of water.

Brew on

#### Dr_Jeff

##### Supporting Member
HBT Supporter
the pressure of a gallon wouldn't provide much benefit

OP
OP

#### Djangotet

##### Well-Known Member
If you want more than 1 psi, get a spunding valve. You could get 1 psi by connecting to the liquid out post of a keg full of water.

Brew on
I was thinking of doing that, filling the second keg with starsan and pushing the water out with fermentation gas. Then finishing the job with my co2 tank. But I’d need 3 kegs to do it, or fermentation bucket. Hmm… might be worth a try.

#### tld6008

##### Master of Nothing
HBT Supporter
Is the very little amount of pressure applied when submerged in a gallon of water enough to reap the benefits or should I just get a spunding valve with a 10psi limit?
.445psi per ft of water column

#### brewbama

##### Well-Known Member
I ferment under ~2 psi until I get to 1-2% of extract remaining, then closed transfer to the keg that was full of iodophors and purged with fermentation CO2, attach a spunding valve, raise the fermentation chamber temp by 5°F to secondary under 30 psi (~2 bar). It’s my effort to allow the yeast to consume inadvertent O2 introduced during xfer and clean up any by-product from fermentation and simultaneously carbonate the beer. I then cold condition under CO2 pressure to keep positive pressure on the inside of the keg as the contents contract.

VLB’s Annemüller documents the process in Managing Fermentation and Maturation of Beer although I think it’s been around longer than that. But he did study the process and document the results as a viable solution. These are the ‘Cliffs Notes’: Fermenting lagers in 21 days

#### D-Max

##### Member
The volume is irrelevant. It doesn't matter whether you put the hose into a gallon of water or the ocean, the amount of pressure needed to push the bubble out of the end of the tube is determined by the head pressure of water over the tube end (so the depth of the tube)
From my diving experience every 30 feet of water above you equals approximately 15 PSI of pressure.
So for 10 PSI you would need a depth of approximately 20 feet.

Replies
3
Views
469
Replies
3
Views
649
Replies
23
Views
924
Replies
5
Views
1K