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Messages - a10t2

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Kegging and Bottling / Re: nothing but foam.....
« on: December 09, 2010, 06:02:22 PM »
Ah yes, the tragic corollary to those times when you need to empty a keg and it just. Won't. Die.

General Homebrew Discussion / Re: Kai in Popular Mechanics!
« on: December 09, 2010, 04:58:29 PM »
Damn that's cool. Way to go Kai!

Equipment and Software / Re: How many BTU's?
« on: December 09, 2010, 07:50:44 AM »
Just as a reference point it would take ~8000 BTU to bring 6.5 gal from room temperature to a boil, assuming no losses. So a burner that's putting out 30,000 BTU/hr could do it in about 15 minutes if it was running at maximum power. Since I don't think you want to run them wide open all the time, figure 45 minutes in real life. Like jeffy said, most basic turkey fryer type burners are in the 50k BTU/hr range. That's what I use and for 5-10 gallon batches they're plenty powerful.

Homebrew Clubs / Re: Any brew clubs in Columbus OH?
« on: December 08, 2010, 08:21:17 PM »
I met some of these guys at a comp; they seem like a fun group.

General Homebrew Discussion / Re: Question about ppm in water chemistry
« on: December 08, 2010, 01:19:49 PM »
They produce the same number, 1 ppm = 1 mg/L, but people prefer to say parts per million.

Technically, that only holds true for low concentrations of the solute. Just an example I have handy: a 1% sucrose solution is 10,000 ppm, but 10,020 mg/L. It's a totally valid assumption at the concentrations we're talking about though.

I would say it seems logical that molecular weight is equal to the sum of the atomic weight of the atoms in the molecule...

That's the idea, although it also turns out to be not quite true. Due to mass-energy equivalence, some weight is actually lost in creating molecular bonds. The effect is several orders of magnitude below anything concerning chemists though, although it becomes measurable for some very large molecules, like transuranic compounds.

Ain't physics fun? ;)

The Pub / Re: Science Friday on Beer
« on: December 07, 2010, 09:56:14 PM »
Makes you wonder what the experts in other fields think of the interviews *you* find interesting, eh?

Questions about the forum? / Re: View poll results?
« on: December 07, 2010, 07:13:06 PM »
Good to know, thanks. It should have occurred to me to look at the poll creation options before asking.

Questions about the forum? / View poll results?
« on: December 07, 2010, 05:47:53 PM »
Hopefully this is just a checkbox an admin can set...

Anyone know if SMF allows you to view the results of a poll without voting? It's a handy little link to have on topics with polls. Just a thought.

Yeast and Fermentation / Re: 1.022 versus on 1.016 on an oatmeal stout
« on: December 04, 2010, 09:21:46 AM »
Was this all-grain? What's the grist like? Oats will add more unfermentables than an equivalent quantity of barley. Is there anything else (lactose, large amount of crystal malt) that would boost the FG?

At 9 days it's possible it isn't done yet. If you can I'd move it to ~70°F and rouse the yeast a few times over the next several days. Check your hydrometer calibration and temperature correction too.

General Homebrew Discussion / Re: Recipe software for MACs
« on: December 03, 2010, 03:40:55 PM »
I think I've at least tried them all. BeerTools Pro is by far my favorite.

Yeast and Fermentation / Re: A couple questions on starters
« on: December 03, 2010, 11:50:22 AM »
I'm not a microbiologist, but, do yeast produce a significant amount of CO2 during aerobic metabolism?

Yes, it's actually the same respiration mechanism as nearly every other aerobic species, including us (the Krebs Cycle). The net reaction for glucose is:

C6H12O6 + 6O2 -> 6CO2 + 6H2O

Yeast and Fermentation / Re: A couple questions on starters
« on: December 03, 2010, 10:05:18 AM »
I'm not in agreement with Denny on the starter gravity.  In talking with Chris White (White Labs) many years ago, he said they culture their yeast using a much lower gravity wort.  He indicated about 1.020, but I see that in his new yeast book, he mentions 1.030 as a prefered starter gravity.  The issue of the Crabtree Effect is more pronounced when you increase the wort gravity, which diverts some yeast metabolic effort into alcohol production instead of yeast mass growth.

AFAIK all the yeast suppliers culture at <1°P (1.004) to avoid the Crabtree Effect entirely. The only reason that isn't a viable approach (pardon the pun) for most brewers is that you need to be able to add precise quantities of wort, and remove precise quantities of alcohol, continually through the entire culturing phase.

Martin's comment about keeping the flask headspace purged with air makes a lot of sense to me.  I would think that even with foil or foam plug you would otherwise tend to have a nice blanket of CO2 on top of the liquid.

I did a sort of one-off experiment to see if that was the case, and it seems that you do get more growth with foil (or foam, presumably) than with an airlock. So I believe that diffusion is able to carry at least some O2 into the headspace to replace CO2.

Aeration and Yeast Starters

The Pub / Re: What's the Weather Like Where You Are?
« on: December 02, 2010, 10:23:57 PM »
I actually live in the caldera of a volcano, but at least it's dormant.

The Pub / Re: What's the Weather Like Where You Are?
« on: December 02, 2010, 09:05:43 AM »
19°F currently, high of 27°F today. Three feet on the ground, and there's supposed to be another 4-8" by the weekend. Days are beautiful, clear blue skies, and it snows almost every night. (We make our own weather.) Highs for the weekend are supposed to be right around freezing, so unless the snow is bad I'm going to get in my last homebrew for the season. The last time it was above freezing was Nov 15. So a really mild winter so far.

And no, I wouldn't trade it for Hawai'i.

General Homebrew Discussion / Re: 32 Oz EZ Cap Bottles
« on: December 02, 2010, 08:58:30 AM »
It won't be quite correct due to the increase in solubility from head pressure, but you can just take a weighted average of the difference between the volumes and subtract it from the difference between the initial and saturation pressures, and get really close. So for example, if you have 32 fl oz of beer at 2.4 vol and 41°F (~1.4 vol saturation) and pour out 12 fl oz, the remaining 20 fl oz will have:

1.4 + (20/32)(2.4 - 1.4) ~= 2.0 vol

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