Spunding Valve Oxygen NEIPA Question

If you time it right, i.e. leave the right amount of not-yet-fermented sugars in the beer when you transfer, there's no need to add any sugar, and you can fully carbonate the beer.

 

Yeah no sugar and .04 - .02 left you’re good to go. If you add sugar you’ll create more Co2 (and aroma) that will get blown off if you set your Valve to the correct setting.

What’s your method for purging the keg?

 

Well, if you know your recipe/process, i.e. you know pretty closely what your FG will be, it should be pretty easy. But if in doubt, I'd say err on the side of transferring when there is more than the sugar you'll need for carbonation rather than less. The spunding valve (properly set) will ensure you don't overcarbonate.

 

This is what a lot of keggers do and it will certainly work. But if going for the extreme, I suggest after keg is sanitized to fill it with water, then pump it out with CO2. With the purge method you never really get all the air out and will use 3 keg's worth of gas (at 20 psi). Pumping out the water will void the keg-space more efficiently and uses less gas (1 keg's worth ~ 2 psi).

How are you transferring from primary to keg?

 

I've thought about doing this before. But I wonder how much water is left in the keg (on the bottom) for an average keg, because there will be some dissolved O2 in that water. I suppose someone could do the math and figure out how much DO that would mean for the beer once it's mixed with the residual water. When purging with CO2, you can get some very low O2 levels, if you're willing to use a lot of CO2. But the O2 in the residual water left by the alternate method would be more or less a constant.

 

Not in my experience . . . remember this is now beer which is generally antiseptic because of the alcohol and a ph of 4'ish.

Either way you go I'll suggest you put a swivel nut on your hose and attach to a liquid quick disconnect. Then fill the keg with lid sealed (PRV open) from the bottom up. It still won't hurt to give Señor Keg a few burps when you finish (for old time sakes) . . . but now you're only purging a tiny headspace.

I've never wondered this but it is a fair concern. I have long dip tubes and after purging (or normal keg-kick) there is only about 1 tablespoon of water/beer remaining. That's not zero but it ain't much. I invert the keg with the PRV open and there is not enough liquid to run out of the open valve.

I suppose if you wanted to go ultra-extreme you could boil the water first, then transfer hot into keg. That'd kill the nasties and if a molecule of oxygen remains it would be tough enough to have my respect.

 

Fill the keg with Star San or Idophor treated water to the very top. Push a pint or two out. Then purge the headspace 8-11 times (I can’t remember the exact number right now) with 30 PSI then push the rest of the water out.

If you cut your dip tube flush you can then tip the keg upside down and tilt it towards the gas side, leave it there for a bit then hookup a gas post and if there’s any water left it’ll flow out. I believe some will come out the PRV if you pull it while upside down as well.

Purging your keg 3 times at 20 PSI leaves a ton of O2 in there.

I also leave 10-20 PSI in the keg, when I hookup the transfer line to the keg it pushes out any possible O2 in the line, hook it up to whatever vessel you’re transferring from when there’s still some CO2 flowing.

The tiniest amount of O2 makes a huge difference in preserved Hop aroma. It’s what goes first.

You can have incredibly hoppy beer last for months if you’re crazy diligent about O2 pickup.

Yes yeast will scavenge some remaining O2 if they’re active but how much? I don’t know that equation, maybe someone smarter than me does.

 

Pretty sure you can find the amount of O2 left in remaing water on the lowdo site, I’ve seen it posted somewhere..

 

We don't need no stinkin' PRVs! (@drink1121 has a spunding valve.)

 

It's a mite slower because gravity has to "push" up the beer as it fill the keg. Just place your primary on counter-top and keg on the floor and it'll work, takes me about 12 minutes for 5 gallons.

I'm comfortable pumping water through the keg, at this level the risk of contamination is nil. I wouldn't put 5 gals of boiling water in a keg at gun-point (pretty sure you picked up on that humor). However, an ounce of starsan will treat 5 gallons of water so it wouldn't be terribly expensive to push all 5 gallons of water treated with starsan.

This also makes a lot of sense and I've been skipping this step (will incorporate). Easy and effective.

About spunding valves: I hear stories they are unreliable . . . anyone have real world experience? Make and Model? Also, much more complex, but you're approaching the area where you have to be concerned with the quality of CO2 you'll be pushing this magnificent IPA. Anyone have a supplier that publishes carbon dioxide purity (and you trust)?

 

My first valve was from one of the online HBSs. I don't remember the model, but it's the one where the body looks like brass. It sucked. Now I build my own and they don't suck.

 

[Edited to add: the TLDR here is that oxygen is not very soluble in water and so I think pushing sanitizer out of the keg with CO2 is likely to be the best approach.]

So I did some back-of-the-envelope calculations on this, and it seems to me that the amount of oxygen dissolved in the residual sanitizer would be small relative to the amount of oxygen likely to remain after purging with CO2 in the traditional way.

To start with, if the internet is to be trusted, under normal conditions room temperature water will have about 10 milligrams per liter of dissolved oxygen. Assuming your keg has half a liter of sanitizer left after pushing the sanitizer out with CO2, that's about 5 milligrams of oxygen.

Compare that to the amount of oxygen in air. Again, if the internet is to be believed (and if I've done my math right), under normal conditions there are about 5 grams of oxygen in 5 gallons of air. You could cut that in half 8 times and still have far more oxygen than would typically be dissolved in half a liter of sanitizer.

I'll make one more observation, which is that the amount of oxygen that dissolves in water is a function of the partial pressure of oxygen in the gas above the water. So let's say you fill your keg with sanitizer and then push it out with CO2. The partial pressure of oxygen in the keg would be very low, and so a lot of the oxygen in the sanitizer would come out of solution. I don't know how quickly that would happen, but when you rack the beer into the keg, a fair amount of the oxygen that was in the sanitizer should be leaving the keg as the gas inside is displaced by beer.

So my strong hunch is that if you're trying to minimize the amount of oxygen in the keg, the sanitizer method is the way to go. Please let me know if I've gotten something wrong. (Would also be curious to hear @TheBeerery's thoughts.)

 

Some data to add to the analysis:

 

Does that chart assume you're starting with a keg full of air or one filled with CO2 (using the fill with starsan method)?