Cold crashing with a CCG

Hence my post #25.

 

I don't think I was taking a shot at your profit margin. I did question the reliability of low cost plastic parts. And throughout the thread I endorsed the concept of the product.

I've been using your camlocks for years. Some time ago, in response to complaints about stiff cam arms (not from me), you explained that it was cost prohibitive to mill stainless for surgical grade smoothness. That makes sense . . . the product is practically indestructible, so what if there is some stiffness if the price reflects that. But I find lower-grade plastic parts in the brewhaus can be a problem. So when plastic is used, I have bought my replacements in advance. I also posted that the OP's results will override my doubt . . . so if the product is still working as designed in 4 years then the crow may be placed on my plate.

Now that you're here, why don't you grab an Avatar and join some discussions? You might find the Home Bar Forum even more to your liking as it's more equipment focused. BTW, you have the most immaculate interior of a ferm fridge I've ever seen.

 

@BrewHardware would be a welcome addition. He (Bobby) knows stuff.

 

If they'll be different, then it's the temp at packaging. Since this whole thing will be sealed, the total CO2 pre- and post-crash will be the same. (And that total CO2 amount will be determined by all the pre-crash numbers, at a spunded equilibrium.) The final temperature, along with beer/fermenter headspace/bag volumes will tell us how it is (re)distributed.

ETA: And if you're going to warm it up, try to estimate the bag volume right before packaging.

 

So...this is the batch that was mostly airlocked and only "bagged" at almost the end? If so, I'm not sure we can make any good calculations about how much total CO2 you started with. If the bag had been attached and spunding for quite a while, we could assume 0.5 PSI, in equilibrium with the beer. But adding late, even if the bag (quickly) got to 0.5 PSI, the beer might not have had CO2 that reached a level that was in equilibrium. I guess we could assume it had reached equilibrium and treat it as an upper bound on how much CO2 was present, but realize that it was likely something less.

 

If the relief valve is operating properly, you shouldn't see any bubbling when it comes back up to temp, unless you bring it up to a temperature higher than the original fermentation temperature.

 

I would be in that camp. A couple of things: There is no real need to raise the temp for bottling. Not necessarily a problem but not a required step. I regularly cold crash in keg and transfer to bottling bucket at keg temp, add the sugar, and bottle. Yes, the beer temp is gradually raising during bottling and a smidgen of CO2 escapes. In theory the last bottle has less carbonation than the first . . . but this is the much ado part.

You're fiddling around with 0.5psi pressures when the gauges we use don't accurately measure that precisely. Assuming you're using the standard homebrew-quality gauges (~10 bucks retail) that's just asking too much. I've compared my Taprite gauges to each other and it's common to be off 1psi . . . that's almost 10% in the range we're talking about. But when beer is force-carbonated there is no detectable difference in carbonation between the "high" gauge and "low" gauge. I have little faith those 0.5psi relief valves are really precision instruments. Again . . . much ado.

Cold crashing and preventing the addition of oxygen is a wonderful thing and it sounds like your process worked. But I fall back to BF's advice of "use your judgement" . . . which is almost always the highest temp the beer was stabilized where CO2 could escape, typically the end of a diacetyl rest.

 

The bag should get bigger when the beer warms up. If it doesn't, that would suggest a leak somewhere.

 

We can work with those numbers. One thing though... since the bag was inflated with CO2 from your tank, post-fermentation, and the fermenter had not been pressurized, you'd have a "regular" post-fermentation CO2 level (and pressure) in the beer and headspace at that point, and the bag would have been at 0.5 PSI (max, because of the valve). So the system could not have been settled at 0.5 PSI, as the beer had not been continuously pressurized at that level over time. But we can compute total system CO2, which is what matters.

Beer CO2 @ 69F (20.6C) @ 1 atmosphere (0 PSI gauge) in 4.9 gallons (18.5 liters):
= 18.5 * 1.977 * (0+14.695) * (0.01821 + 0.090115 * EXP(-1*20.6/23.95))
= 30.3 grams

Fermenter Headspace CO2 @ 20.6C @ 0 PSI gauge in 2.9 gallons (11 liters):
= 11 * 1.977 * ((0+14.695) / 14.695) * (273.15 / (20.6 + 273.15)):
= 20.2 grams

Bag CO2 @ 20.6C @ 0.5 PSI gauge in 2.4 gallons (9.1 liters):
= 9.1 * 1.977 * ((0.5+14.695) / 14.695) * (273.15 / (20.6 + 273.15)
= 17.3 grams

So, total system CO2:
= 30.3 + 20.2 + 17.3 = 67.8 grams

Since we know there are about 67.8 grams of CO2 in the system, we can use the above formulas to solve for the settled pressure and thus the beer CO2 volumes that result from 67.8 grams of CO2 at 70F, in 18.5 liters of beer, 11 liters of fermenter headspace and 2.5 gallons (9.5 liters) of bag headspace. It's an iterative process to solve, at least the way I did it, so I can't show it. But the answer is: 0.82 volumes of CO2, which is very close to what you'd expect at the end of a typical fermentation.

I think this would be a much more interesting exercise with the guardian used during fermentation, so that a constant spunding pressure of 0.5 PSI would force additional CO2 to remain in the beer (and fermenter headspace). As it was, we just (more or less) computed a typical residual CO2 (plus a filled bag of CO2) and redistributed it slightly for equilibrium at a slightly different temperature. BTW, the formulas can be found in a few threads on another forum. I'm not posting them here out of respect for the Bros' turf.

 

This was my hypothesis (and Brewer's Friend) from the beginning . . . 0,5psi can be ignored. While doing the math is interesting, it doesn't change much from "using your judgment". You have a good feel for where the temp was stabilized and CO2 was able to equalize. I've been doing this same drill for years with good results.

For what's important: from your description, it appears the Guardian works as hoped for. The leaks you describe are manageable and it put to rest my doubts if the size was adequate. It's a shame BH didn't stick around for the victory lap. You probably aren't up for a true A/B test (who is?), but using the Guardian on an IPA might help prove it's attributes as the hop aromas age.