Can we dispel the myth of the 'CO2 Blanket' ?

[Snuffy]

That's a good system.

For me, rather than use a hop bong, I have been using a hyperbaric chamber. I crawl inside the chamber, bringing the fermenter with me. I have the chamber filled with co2.

When I open the fermenter and add the hops, the entire environment is co2, so there is zero oxygen ingress.

I am wearing scuba gear so I can breathe in the chamber.

Photo attached.

Do you vary your diet at all the day before?

 

[VikeMan]

That's how Kegland says to do it. @Bobby_M sold me the bong and his advice was to do it with the prv open and a constant flow, so that is what I do.

We are guessing here, as we can't see what is happening. But Bobby's method makes sense to me.

Perhaps you could ask to see Bobby's calculations and/or measurements.

For comparison, most people purging kegs use a series of pressurize/release cycles. I haven't calculated the efficiency of the "continuous flow" method, but I'd be willing to bet a beer or two that it's more expensive to reach a given O2 concentration (in terms of total CO2 needed) than the pressurize/release method. @doug293cz did you take a whack at this before?

The pressurize/release is method easy enough to model, and easier with a cheat sheet. No guessing.

 

[Zadkiel]

small nitpick but that seems to be calculating ppm in the bong, not in the headspace. When the bong is opened there will be a dilution based on the volume of CO2 in the headspace and the Volume of the gasses in the hop bong, which is going to be different for each and every setup so not feasible to account for - but you labelled it as ppm in headspace so I'm being pedantic

Maths looks good to me, my napkin math got 4.5% O2 earlier in the thread for 3 cycles at 10 PSI (as that's what I read in the fermzilla bong instructions) and that's what you get there too (well, closer to 4.4%, but I was using appoximations: 21% O2 and 15PSI atmospheric pressure, which would account for my slight inaccuracy)

 

[BrewZer]

Have any calculations taken into account the embedded O2 present in the hops pellets/cones themselves, and how, exactly would you calculate that?

Yes, your hops probably came to you in a nitrogen-filled vacuum pack, but as soon as you opened it, all those nasty O2 molecules rushed in and contaminated the pellets.

Perhaps the ritual should include an O2 purge cycle for the hops prior to putting them into the hop dropper...? You know, like 24 hours bathed in a bowl full of dry ice or something...

 

[Zadkiel]

Yes, your hops probably came to you in a nitrogen-filled vacuum pack, but as soon as you opened it, all those nasty O2 molecules rushed in and contaminated the pellets.

You aren't opening your hops in a vacuum sealed chamber? Amateur!

 

[VikeMan]

small nitpick but that seems to be calculating ppm in the bong, not in the headspace. When the bong is opened there will be a dilution based on the volume of CO2 in the headspace and the Volume of the gasses in the hop bong, which is going to be different for each and every setup so not feasible to account for - but you labelled it as ppm in headspace so I'm being pedantic

In the "bong," the total volume is the "headspace," for the purposes of calculation. Yes, it's labeled as "headspace" because it was originally made for keg purge calculations. But it applies equally to any enclosed gas space.

 

[Zadkiel]

I guess we're just using headspace differently, to me the common use of headspace is the area of gasses inside the fermenter. Yes, technically the gasses in the sealed bong is also a headspace, but I think anyone reading your chart would assume incorrectly But it's your own tool.

 

[VikeMan]

Have any calculations taken into account the embedded O2 present in the hops pellets/cones themselves, and how, exactly would you calculate that?

I know you're joking, but just for the record... there's no need (even a theoretical one) to calculate that. The hops themselves take up some space, and thus reduce the volume of the gas space, but the volume doesn't matter (for the purge/release calculation).

 

[Brockness Monster]

Limnic Eruptions, perhaps the largest of all CO2 blankets. Once in a lifetime opportunity for the avid LoDO brewer

And yes, before someone points something out, I understand the CO2 emission during a Limnic Eruption is colder than atmospheric temps which causes it to fall and suffocate ungodly amounts of humans and livestock. this was meant as a joke, don't @ me.

 

[VikeMan]

Yes, technically the gasses in the sealed bong is also a headspace, but I think anyone reading your chart would assume incorrectly But it's your own tool.

I suppose they could assume whatever they want in this case, but the result would be the same regardless. The O2 concentration left in the whole enclosed part of the hop dropper will be the same throughout... top, bottom, middle, above or below the injection point. All the same.

 

[Zadkiel]

Yes, it's labeled as "headspace" because it was originally made for keg purge calculations.

Oh, right, I see now. You built this in the context of a different simulation where that 'headspace' wasn't then being opened up to another volume. Sorry I was looking at the chart purely in the context of hop bong into fermenter. Got it.

 

[BeerNsteadofH2O]

with all this rampant running 02 spoiling everyone's beer it's Time to take up knitting