Spunding Valve Oxygen NEIPA Question

That chart assume (I think) air, at atmospheric pressure.

 

Will probably get flagged as spam but here is my take on it.

http://www.lowoxygenbrewing.com/bre...rging-transferring-stabilizing-finished-beer/

 

How's everybody that ferments in carboys getting the transfer started? I've performed closed transfers out of glass carboys using CO2 but that scares the crap out of me and I don't do it anymore for fear of shattering the carboy if something goes wrong. I'm sure the cap would pop off before it shattered but you never know when dealing with pressure and a glass vessel that isn't designed for high pressure. It seems like gravity never was able to keep the liquid flowing without constant pressure in the headspace of the carboy for me.

One of those sanitary filters seems like it would work fine getting it started but the idea of blowing oxygen/CO2/whatever else we exhale has me wondering why anyone would go that route vs. using an auto syphon with the hose connected to the liquid ball lock.

 

This is roughly what I do.

Push out star san with CO2, then purge keg x2 (this time through dip tube) and vent through pressure relief valve at 20 psi, then x1 slow same way at 1-2 psi with pressure relief valve open for a few mins, fill with 10 psi, tip keg upside down & wait a few mins then empty remaining Star san through gas in post.

 

You only have to use 1 PSI to get the liquid high enough to start the siphon. 1 PSI will force the liquid 27.7 inches upwards, more than enough to do it.

 

I would not put a lot of faith in those numbers. As I understand it, the sampling method was questionable at best. Traditional O2 meters are famously temperamental to calibrate and maintain. The values reported real funky too. Confidence level is just about zero.

If we are to believe 20 purges at 25 psi are required to obtain 0.00 ppm saturation, well, maybe. But based on what we do not know.

Just saying.

 

I don't think this chart represents empirical results, it is an analytical result under certain assumptions. Basically the concept is that if you hook up your CO2 tank, pressurize the keg, turn off the CO2, and then vent, and then repeat, you will eliminate a certain percentage of the oxygen in the keg each cycle. I don't keg and I can't comment on the realism of the assumptions, but I think the chart is just a mathematical extrapolation from the assumptions.

Now I'm curious how people purge their kegs and whether they think the assumptions are realistic.

 

IIRC, they are not based on measurement. They're based on computations. There was a similar discussion in another thread. The only thing that must be "believed" is that when you pressurize a keg, turbulence from pressurizing equally mixes the old and new gasses.

Here's the thread:
https://www.beeradvocate.com/community/threads/sugar-addition-to-purge-o2.555679/

 

I thought there were a few actual measurements?, questionably collected. Starting with 21% atmosphere we end up with all those numbers?

What I'm saying is that this chart is basically useless as a scientific analysis of keg purging.
A lot has been made of the utility of keg purging. If this is the foundation of the discussion, we should reconsider.
Cheers.

 

That was a fun one!
Not trying to sidetrack this conversation but it is an important consideration.

The part where you can get to 0.00 ppm DO with 20 purges at 25 psi... and goes on to claim bottle CO2 is 500 ppb oxygen... so if we are provided that value how does that figure into the chart? We just ignore that part?

So, it's ND or it's not ND. ?????
An entire business model falls apart when you question some basic assumptions. I'm one guy who is thoroughly not impressed. Packaged real well, but the evidence is based on some questionable work.
Cheers.

 

I don't think the chart was made by @TheBeerery, and AFAIK it does ignore whatever trace O2 is in bottled CO2. BTW, I don't believe he ever claimed 500 ppb. I believe it was 150. When you think about how small 150 ppb is, you will realize that including it in the chart would not change a thing; it's less than rounding error when measure ppm.

To me, the important takeaway from the chart isn't really "X purges at Y pressure will get you to 0 ppm" (though I really don't doubt the math or the purge/dilution equation behind it). It's that the 4 or 5 purge cycles that a lot of people do doesn't really get you very close. Everyone can decide for themselves if ~1000 ppm is good enough for their beers.

 

I use this calculator. When i get my meter i'm going to video some tests in the keg with my action camera. Curious to see how much 02 is left in those small kegs after purging.
https://www.purgesolutions.com/wizard/flowCal.php

 

Nice summary, and you are correct the claimed ppb in bottle CO2 is 150 ppb, though that is probably also dubious. But 150 is not 500 none the less.

Maybe the 4 or 5 purges really does get headspace O2 down to an acceptable and practicle amount. We can discuss "acceptable and practical amount", there is plenty of data for that around. But the chart is useless and it should be ignored. Which is why I say don't put too much faith in those numbers. As an aside, I think it is appalling that an entire cottage business is predicated on a foundation of bullshit. Full stop.

Cheers.

 

Why do you say that?

 

For those of you that regularly use a spunding valve, what do you do to manage dry hops? If you were to dry hop at high krausen for example, there would still be some hop debris flying around when you transfer with a few gravity points left - do you just rack over to the serving keg w/ hop bits included or do you use bags ?

I normally go bagless for max extraction but am stumped on how to do this on a NEIPA without using hop bags.

 

Floating Diptube.

 

Yeah, the only issue I have is similar to what @thebriansmaude is talking about. I've had an issue where dry hops clogged the ball lock on a closed transfer and I had to stop it and whip out the auto syphon.

I think I might just start dry hopping in the carboy during active fermentation with muslin bags so I can go back to closed transfers and not have to worry about a clog, followed by a dry hop in the keg with floss tied to the lid so I can remove it after the fermentation is done, prior to chilling. It's such a pain in the ass getting bagged hops in and out of a carboy though. I did a dry hop process like this on my most recent IPA and I was satisfied, no closed transfer though.

 

I know these discussions have gotten heated in the past, and I don't want that to happen again, but I do think the chart is basically valid. You can quibble with the number of significant digits, but that's not really the point. The point is that even after numerous purging cycles, the amount of oxygen remaining in the keg can be significant. And the chart is a straightforward application of math based on reasonable assumptions.

I've done some back-of-the-envelope calculations, and as far as I can tell at 20°C (68°F), there are about 0.042 moles of gas in a liter of atmosphere. So you can take the liters of head space in your keg, multiply it by 0.042, multiply it by the parts per million from the chart, and divide by a million, and you'll have moles of O2 in the headspace.

Then each mole of O2 that dissolves into 5 gallons of beer represents an increase of about 1,670,000 ppb. (A mole of O2 should weigh about 32 grams, which is divided into 19 liters of beer weighing about 1,010 grams per liter.)

So to give a few examples, if you have a liter of headspace and you've purged 5 times at 30 psi, the remaining oxygen would be enough to increase the dissolved oxygen in the beer by about 57 ppb. (I am making the simplifying assumption that all of the oxygen in the headspace will eventually dissolve into the beer.) If you look at the original post, you will see that this represents a large fraction of the total O2 that might be found in packaged beer produced by a professional brewery. (Bear in mind I'm assuming a liter of headspace. I don't know how realistic that is, but adjust the numbers according to your own situation.)

By contrast, if you purge 4 times at 30 psi, then the remaining oxygen would be enough to increase the dissolved oxygen in the beer by about 172 ppb. That is more than the total O2 you would find in packaged beer from a professional brewery, and that's just the oxygen from the keg's headspace after the keg has been purged 4 times with CO2! With three purge cycles at 30 psi, you're picking up about 523 ppb.

(Everyone should feel free to double-check my math, I could easily have gotten something wrong.)

So that's why I think the chart is helpful—it gives you a sense of how many purge cycles you have to complete to get to reasonable levels of O2. Of course, your definition of "reasonable levels of O2" is subjective, and you could easily conclude that picking up 57 ppb or 172 ppb or whatever is an acceptable result. On the other hand, you could also decide that you prefer the 15 ppb that @TheBeerery calculates would be contributed if you use the sanitizer method. Or of course you could go whole hog and use his recommended "fermentation purge" method, in which you fill the keg with CO2 produced during fermentation. But you can't make these decisions on an educated basis unless you have a chart like the one under discussion, and so I think it is useful.

 

That chart says air is 210,000 ppm oxygen. That is to say 21%. Well, actually it states that air is 210,000.00 ppm. But air is not 21% oxygen, it is 20.95% oxygen. That does of course matter if you are presenting the foundation of your data on a known fact. It's PF sloppy. It is not nit picking to note this ridiculously lazy reporting.

So then the numbers go on to extrapolate data based on false information. And that is sloppy.

Hey, what's 0.05% anyway? That's 500 ppm in fact. Now, is 500 ppm oxygen relevant? Based on the authoritative data presented it would seem to be. Doesn't really matter. The whole chart is wack just based on that.

And it is a model, not fact.

GIGO. As I said the foundation is bullshit. Grab samples from the headspace and have them analyzed at a lab if you must, then take it from there.

We don't, as a rule, want to work out ways to make the data real and relevant. That is my opinion.
Cheers.

 

But it's not comparable to, say, a macroeconomic or meteorological model that of necessity involves a tremendous amount of simplification and measurement error. With those models, it's reasonable to apply a fair amount of skepticism (although actually meteorological models are pretty impressive these days). The chart, by contrast, is just a straightforward mathematical exercise. It's a model in the same way that multiplying the last 2-3 digits of your specific gravity by your volume gives you a measure of the amount of sugar in your wort, which you can then divide by expected final volume to figure out what your SG will be after the boil. That's a "model" but it's also pretty much a fact, and no one would question its accuracy or usefulness. The chart is based on a comparable level of extrapolation from observable facts, though the math might be a bit harder.

At worst the table is misleading in its level of precision. Fair enough, I agree that it's silly to specify numbers to the hundredths when you've started with a round number. But as I said, that's just a quibble. The chart is not really "off by 500 ppm," but rather off by about a quarter of a percent, which is equal to 500 ppm only at the first, no-purge stage. If I used the chart to calculate that I would get 57 ppb of oxygen in my beer, and the real answer turned out to be 56.8 ppb, it wouldn't change anything.

In short I don't think your skepticism is justified here. People can decide for themselves whether oxygen exposure is a big deal for their beers, and this chart may be irrelevant to some people, but the chart is fundamentally sound and it shouldn't be dismissed merely because of a questionable choice on significant digits.